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  • Electronic Resource  (725)
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  • 1990-1994  (725)
  • 1990  (725)
  • Biochemistry and Biotechnology  (725)
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  • Electronic Resource  (725)
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  • 1990-1994  (725)
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  • 101
    Electronic Resource
    Electronic Resource
    Effect of regulatory mechanism on hyperbolic reaction network properties (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 166-178 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The notion that the regulated and flux-controlling enzyme in a metabolic network need not correspond suggests that the purpose of regulation may not be flux homeostasis under all physiological circumstances. Additionally, the fact that diversity in the function of intact metabolic networks exists suggests that in addition to time constant separation, other kinetic structure/regulatory mechanism patterns exist. In order to compliment and expand prior work on identifying kinetic structure-property relationships in networks, the present work explores in a general way how the control, dynamic, and energetic properties of metabolic networks depend on operating point, kinetic structure, and regulatory mechanism. The basic feature of trade-offs between properties is illustrated and used as a basis for indicating how particular subsets of structure, regulatory mechanism, and operating point emphasize certain properties that can be associated with a physiological function. Examples of scavenging trace metabolites and amphibolite coordination are proposed. Microstructure logic in terms of turnover number distributions as well as a potential mixed polynomial network analysis approach are also discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360209
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  • 102
    Electronic Resource
    Electronic Resource
    Kinetic analysis of the growth of Chlorella vulgaris (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 198-206 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The energy of the total transmitted light was subtracted from that of the incident light in a culture vessel and the difference was divided by the weight of cells. The value thus obtained was defined as the amount, Ex, of light energy absorbed per unit cell weight per unit time.Batch and continuous cultures of Chlorella vulgaris were carried out at 30°C in the pH range of 6.4-6.7 while restricting illumination. Next the specific growth rate, μ, in the batch culture and the fixed dilution rate, D, in the continuous culture were plotted against Ex. The results showed that the relation between D and Ex can be expressed in a Michaelis-Menten equation, where the maximal specific growth rate is 0.24 h -1 and the saturation constant is 6.58 kcal/g · h.Cell concentration calculated by substituting the apparent concentration, Xe, of incubated cells and the apparent maintenance constant, Me, for this equation agreed with that observed in almost all growth phases. Furthermore, from the change of chlorophyll productivity and the relationship between D and Ex expressed in this equation, it is assumed that Ex involves the light energy directly utilized in photosynthesis in the cells and that which is converted into, e.g., heat. This equation also indicated that a maximum in the growth yield existed. Then the growth yield of 0.029 g/kcal obtained at the incident light of 1.46 or 2.63 cal/cm2 · h was maximum (maximal conversion efficiency of light energy, 15.6%).These results indicate that this method of deriving the equation for the growth rate from this study is a useful procedure for obtaining bioengineering findings.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360212
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  • 103
    Electronic Resource
    Electronic Resource
    Analysis of pBR322 replication kinetics and its dependency on growth rate (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 233-242 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Accurate estimates of plasmid copy number in a cell are a prerequisite for predicting plasmid stability and protein production. A refined version of a structured model for the pBR322 plasmid replication mechanism is described. The model is capable of accurately predicting pBR322 plasmid copy number in Escherichia coli B/r for a wide range of growth rates. The refinements include better estimates of promoter strength, the degradation rate of RNA species, binding constant of RNAI-RNAII reaction, and dependency of promoter strength on growth rate. The predictions of the model are verified by recent experimental observations but differ from some previous reports. This model can also be used to predict the binding constant of the RNAI-RNAII reaction of ColE1 type plasmids. At 37°C, the binding constant is estimated to be 77 ± 11 × 10-13 mL/molecule-h for pBR322.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360304
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  • 104
    Electronic Resource
    Electronic Resource
    Solvent selection for biocatalysis in mainly organic systems: Predictions of effects on equilibrium position (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 691-701 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Predictions may be made for the influence of solvent choice on the equilibrium position of biocatalyzed reactions, based on data for the liquid-liquid distribution of the reactants. The most reliable predictions are probably for dilute systems, based on partition coefficients or correlations derived from them. The effective equilibrium constant for esterification reactions is predicted to alter by more than four orders of magnitude on changing between different water-immiscible solvents. The equilibrium constant correlates well with the solubility of water in the solvent, and is most favorable for synthesis in the least polar solvents (aliphatic hydrocarbons). Similar effects seem to apply for other reactions, including oxidation of alcohols and hydrolysis of chlorides. Predictions can be made for nondilute systems using the UNIFAC system of group contributions, but the reliability of these is more questionable.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350706
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  • 105
    Electronic Resource
    Electronic Resource
    Optimum ph and temperature conditions for xylose fermentation by Pichia stipitis (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 727-731 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pichia stipitis NRRL Y-7124 is a xylose-fermenting yeast able to accumulate ca. 57 g/L ethanol. Because optimum process conditions are important, data were collected to determine the effects of temperature and pH on growth and fermentation rates and product accumulations. Temperatures (26-35°C) providing optimum biomass and ethanol productivities did not necessarily provide maximum ethanol accumulation. Xylitol and residual xylose concentrations increased with temperature. Maximum ethanol selectivity was achieved at 25-26°C with minimal sacrifice to production rates. The temperature optimum for xylose could not be generalized to glucose fermentations, in which ethanol productivity and accumulation were optimum at 34°C. The optimum pH range for growth and fermentation on xylose was 4-7 at 25°C.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350710
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  • 106
    Electronic Resource
    Electronic Resource
    Enzyme production by genetically engineered Streptomyces strains: Influence of culture conditions (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 719-726 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Production of various extracellular enzymes (the β-lactamases from Streptomyces albus G, Streptomyces cacaoi, Actinomadura R39, and the DD-carboxypeptidase from Streptomyces R61) by genetically engineered Streptomyces lividans TK24 in Lennox broth medium reached a maximum after 36 to 48 h. Subsequently, the enzyme activity drastically decreased probably due to an increased pH value and the production of an inactivator by Streptomyces lividans. Protease activity did not seem to play a major role. The increased pH and inactivator synthesis are related to amino acid catabolism and generally result in cellularlysis. The use of a medium where the catabolism of amino acids was made less likely by the presence of glucose and NH4Cl and by buffering at pH 7.4 considerably inproved the yield. Furthermore, the water activity of the medium seemed to be an important parameter for the production of extracellular proteins by genetically engineered Streptomyces. Better production was observed when the water activity was decreased to 0.96-0.98 by addition of sucrose.Under those conditions, the concentration of extracellular enzyme reached about 0.3 g (1 g in the best case)/L of culture supernantant.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350709
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  • 107
    Electronic Resource
    Electronic Resource
    Characterization of an immobilized cell, trickle bed reactor during long term butanol (ABE) fermentation (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 207-217 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Acetone-butanol-ethanol (ABE) fermentation was performed continuously in an immobilized cell, trickle bed reactor for 54 days without, degeneration by maintaining the pH above 4.3. Column clogging was minimized by structured packing of immobilization matrix. The reactor contained two serial glass columns packed with Clostridium acetobutylicum adsorbed on 12- and 20-in.-long polyester sponge strips at total flow rates between 38 and 98.7 mL/h. Cells were initially grown at 20 g/L glucose resulting in low butanol (1.15 g/L) production encouraging cell growth. After the initial cell growth phase a higher glucose concentration (38.7 g/L) improved solvent yield from 13.2 to 24.1 wt%, and butanol production rate was the best. Further improvement in solvent yield and butanol production rate was not observed with 60 g/L of glucose. However, when the fresh nutrient supply was limited to only the first column, solvent yield increased to 27.3 wt% and butanol selectivity was improved to 0.592 as compared to 0.541 when fresh feed was fed to both columns. The highest butanol concentration of 5.2 g/L occurred at 55% conversion of the feed with 60 g/L glucose. Liquid product yield of immobilized cells approached the theoretical value reported in the literature. Glucose and product concentration profiles along the column showed that the columns can be divided into production and inhibition regions. The length of each zone was dependent upon the feed glucose concentration and feed pattern. Unlike batch fermentation, there was no clear distinction between acid and solvent production regions. The pH dropped, from 6.18-6.43 to 4.50-4.90 in the first inch of the reactor. The pH dropped further to 4.36-4.65 by the exit of the column. The results indicate that the strategy for long term stable operation with high solvent yield requires a structured packing of biologically stable porous matrix such as polyester sponge, a pH maintenance above 4.3, glucose concentrations up to 60 g/L and nutrient supply only to the inlet of the reactor.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360213
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  • 108
    Electronic Resource
    Electronic Resource
    The pH-auxostat as a tool for studying microbial dynamics in continuous fermentation (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 224-232 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: If a microorganism has a growth coupled production or consumption of acid or alkali, it is possible to use the pH-auxostat as a means of control in continuous fermentation. In using the pH-auxostat, it is possible to separate the inlet substrate flow in two different streams. These will both be pH controlled, with one main flow, consisting of nutrients and a second minor but concentrated flow, of acid or alkali. Hereby, it is possible to vary the difference in pH between the fermentor and the inlet medium. This pH difference is proportional to the steady-state cell mass concentration.1,2 It is shown that by separating the inlet flow in two different streams and cultivating without any substrate limitation, the maximum growth rate may be obtained while the cell mass concentration will be controlled. This will also give the possibility to reach high cell mass concentrations at μmax without the risk of wash-out. A modified expression, based on hydrogen, of the steady-state bio-mass concentration, X, is developed as \documentclass{article}\pagestyle{empty}\begin{document}$$ X = Y_{X/H} \cdot [F_{{\rm Hin}} /(F_{{\rm Hin}} + F_{{\rm Min}} )] \cdot (C_{{\rm Hin}} - C_{{\rm HFERM}} ) $$\end{document} where YX/H is the yield coefficient of cell mass per acid produced. The indexes Hin and Min refer to the inflows of alkali and medium, respectively; CHin is the inlet concentration of hydrogen ions. The boundary condition for the cell mass shows that Sin 〉 X/YX/S, where Sin is the medium substrate concentration and YX/S is the yield of biomass per consumed substrate. It is shown that when the cell mass concentration exceeds this value, the flow stops. The applicability of the pH-auxostat method is then verified from different experiments. It is hereby used to detect a deviation from the maximal growth rate showing effects on the microbial physiology. With Escherichia coli used as the model organism, the effect on the growth rate of temperature and high concentration of ammonia were investigated.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360303
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  • 109
    Electronic Resource
    Electronic Resource
    Production of essential L-branched-chain amino acids in bioreactors containing artificial cells immobilized multienzyme systems and dextran-NAD+ (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 263-269 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We prepared artificial cells each containing leucine dehydrogenase (EC 1.4.1.9), urease (EC 3.5.1.5), soluble dextran-NAD+, and one of the following coenzyme regenerating dehydrogenases: glucose dehydrogenase (EC 1.1.1.47); yeast alcohol dehydrogenase (EC 1.1.1.1); malate dehydrogenase (EC 1.1.1.37); or lactate dehydrogenase (EC 1.1.1.27). Artificial cells were packed in small columns. L-Leucine, L-valine, and L-isoleucine were continuously produced with simultaneous dextran-NADH regeneration. The maximum production ratios depended on the coenzyme regenerating systems used: 83-93% for D-glucose and glucose dehydrogenase system; 90% for ethanol and yeast alcohol dehydrogenase system; 45-55% for L-malate and malate dehydrogenase system; and 64-78% for L-lactate and lactate dehydrogenase system. Kinetic experiments were also carried out. The apparent Km values are as follows: 0.33 mM for α-ketoisocaproate (KIC); 0.51 mM for α-ketoisovalerate (KIV); 0.58 mM for DL-α-keto-β-methyl-n-valerate (KMV); 3.52 mM for urea; 27.82 mM for D-glucose; 3.89 mM for ethanol; 3.02 mM for L-malate; and 16.67 mM for L-lactate. Kinetic analysis showed that KIC, KIV, and KMV were all competitive inhibitors in the reactions catalyzed by leucine dehydrogenase. Their inhibitor constants were the corresponding Km values.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360308
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  • 110
    Electronic Resource
    Electronic Resource
    Group contributions for estimating standard gibbs energies of formation of biochemical compounds in aqueous solution (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 1070-1082 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method is presented for the estimation of the standard Gibbs energies of formation of biochemical compounds (and hence the Gibbs energies and equilibrium constants of biochemical reactions) from the contributions of groups. The method employs a large set of groups and special corrections. The contributions were estimated via multiple linear regression, using screened and weighted literature data. For most of the data employed, the error is less than 2 kcal/mol. The method provides a useful first approximation to Gibbs energies and equilibrium constants in biochemical systems.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260361013
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  • 111
    Electronic Resource
    Electronic Resource
    Decrease in iron oxidizing activity of Thiobacillus ferrooxidans adsorbed on activated carbon (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 1105-1109 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It was observed that about 90% of free-swimming Thiobacillus ferrooxidans in 9 K medium was adsorbed on added activated carbon when the concentration of the cultivated bacteria reached about 4 × 1013 cells m-3. The oxidation of ferrous iron and the leaching of copper ore were carried out in shake flasks and in aerated columns. The rates of oxidation and leaching increased when bacteria adsorbed on activated carbon were used. However, the evaluation of the reaction rates by eliminating the catalytic effect of activated carbon showed that the contribution to the reaction by the adsorbed microorganism was very small.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260361105
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  • 112
    Electronic Resource
    Electronic Resource
    High-level recombinant protein production in bioreactors using the baculovirus-insect cell expression system (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 1133-1140 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to develop an efficient process for large-scale production of recombinant protein, various factors were studied which affect the productivity of Sf-9 (Spodoptera frugiperda) insect cells when using the baculovirus expression system. It was shown that upon infection with the Bac-BRV6L recombinant baculovirus, the level per cell of VP6 (a bovine rotavirus nucleocapsid protein) would drop 10-fold when host cell density at the time of infection increased from 2 × 106 to 3 × 106 cells/mL. The decrease was found to be totally reversible by culture medium renewal after infection, even when cells were infected at the stationary phase. Recombinant protein production was 4-6 times higher using TNMFH medium supplemented with 10% fetal bovine serum (FBS) than in IPL/41 serum-free medium. Fine-tuning of infection parameters in a 4-L surface-aerated bioreactor resulted in the production of typically 350 mg/L of VP6 protein, representing more than 25% of total cell proteins.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260361108
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  • 113
    Electronic Resource
    Electronic Resource
    Kinetic studies and unstructured models of lymphocyte metabolism in fed-batch culturePresented in part at the 80th annual meeting of the American Institute of Chemical Engineers, Washington, DC, November 27-December 2, 1988. (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 797-807 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The growth of two lymphocyte cell lines, a hybridoma cell line and a human cutaneous T cell lymphoma (HuT78), was studied in fed-batch culture, and unstructured models of growth developed. A criteria was established to insure that the growth rate varied by less than a specified tolerance throughout the culture period. Glutamine and serum were growth-limiting nutrients for both cell lines with half-maximal growth rates at 0. 53 mM glutamine and 0. 55%(v/v) serum for the hybridoma cells and 0. 21 mM glutamine and 1. 5% serum for the HuT-78 cells. Over the range of glucose concentrations from 5. 5 mM to 28 mM, the specific growth rate of hybridoma cells was independent of glucose concentration, whereas glucose concentrations above 5. 5 mM inhibited HuT-78 growth. For both cell lines, the growth rate was significantly inhibited by the addition of ammonium, although the hybridoma cell line was more affected by ammonia than was the HuT-78 cell line. Growth of HuT-78 cells increased in the presence of interleukin-2. Unstructured models for the hybridoma cells were similar to other models presented in the literature. Applications of these models to adoptive immunotherapy are discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360807
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  • 114
    Electronic Resource
    Electronic Resource
    A stochastic model to simulate the growth of anchorage dependent cells on flat surfaces (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 547-562 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A stochastic model is proposed to simulate the growth of anchorage dependent cells on a flat surface. The model, based on representing the cell shapes on the surface as external irregular polygons with the nuclei distributed as a set of Poisson points (producing a modified Voronoi tessellation of 2 space) and incorporating a distribution function to describe cell division of the perimeter cells of the colony, provides data not only on population dynamics but also on the patterns produced by clusters of cells in the colony. These patterns produced by the model are qualitatively similar to observations reported for some cell cultures. The periods of induction, rapid growth, and decreasing growth asymptoting to zero as confluence is reached are predicted by the model. Quantitative comparison with published experimental data for this is good. The specific growth rate computed for the period of rapid growth predicted by the model is dependent on the distribution function describing the cell division time. As the standard deviation of this increases, the specific growth rate decreases as with a consequent increase in time to achieve confluence. The removal of cells from the colony by shear forces or death is considered in the model. As the probability for removal increases, the cell density at confluence and specific growth rate decrease. The clusters of cells, patterns, in the colony are very sensitive to cell removal. By analyzing these patterns in experiments, an estimate of cell removal can be made. The areas covered by cells on a substrate are fractal patterns. The fractal dimension is always greater than 1 and is a function of the removal probability.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360602
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  • 115
    Electronic Resource
    Electronic Resource
    Lipoprotein lipase immobilization onto polyacrolein microspheres (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 593-600 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A lipoprotein lipase (LPL) was made water insoluble by immobilizing onto the surface of polyacrolein (PAA) microspheres with and without oligoglycines as spacer. The activity of the immobilized LPL was found to remain high toward a small ester substrate, p-nitrophenyl laurate (pNPL). The relative activity of the immobilized LPL without spacer decreased gradually with the decreasing surface concentration of the immobilized LPL on the PAA microsphere. On the contrary, the immobilized LPL with oligoglycine spacers gave an almost constant activity for the substrate hydrolysis within the surface concentration region studied and gave a much higher relative activity than that without any spacer. The Michaelis constant Km and the maximum reaction velocity Vm were estimated for the free and the immobilized LPL. The apparent Km was larger for the immobilized LPL than for the free one, while Vm was smaller for the immobilized LPL. The pH, thermal, and storage stabilities of the immobilized LPL were higher than those of the free one. The initial enzymatic activity of the immobilized LPL maintained almost unchanged without any leakage and inactivation of LPL when the batch enzyme reaction was performed repeatedly, indicating the excellent durability of the immobilized LPL.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360606
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  • 116
    Electronic Resource
    Electronic Resource
    Effects of cell density and glucose and glutamine levels on the respiration rates of hybridoma cells (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 630-635 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of cell density as well as the concentration levels of glucose and glutamine on the specific respiration rate of a hybridoma cell line were investigated. The experimental oxygen consumption rate was found to be constant over a wide range of dissolved oxygen levels if the suspension medium contained glutamine. In glutamine-free medium, however, the rate of oxygen consumption decreased slowly with time.In a stationary flask batch culture, the specific respiration rate decreased from about 7 to 2.9 μmol/min per 109 cells as the cell density increased exponentially from 1 × 105 to 1.2 × 106/mL. To isolate the effect of cell density, cells were re suspended in fresh culture medium so that nutrient concentrations were the same for all experiments. The specific respiration rate decreased with increasing cell density in the same manner as in the stationary flask culture, falling from 8 to 4 μmol/min per 109 cells as the cell density increased from 105 to 106 cells/mL, then declining to 2 μmol/min per 109 cells when the cell density reached 107 cells/mL.Cells suspended in Hanks balanced sale solution (HBSS) were used to elucidate the effect of glucose and glutamine levels on respiration. The addition of glucose in concentrations of 0.25, 0.50, and 0.75 g/L had no observable effect on the specific oxygen uptake rate; however, a glucose concentration of 1 g/L reduced the uptake rate by 22%. Glutamine in a concentration of 0.30 g/L increased the specific respiration rate in HBSS containing 0 and 1 g/L glucose by approximately 13%.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360611
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  • 117
    Electronic Resource
    Electronic Resource
    Aerosol release from aerated broths (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 970-973 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360913
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  • 118
    Electronic Resource
    Electronic Resource
    Cell growth and death rates as factors in the long-term performance, modeling, and design of immobilized cell reactors (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 983-992 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The viable fraction of immobilized cells in a bioreactor may be critical in predicting long-term or steady-state reactor performance. The assumption of near 100% viable cells in a bioreactor may not be valid for portions of immobilized cell reactors (ICRs) characterized by conditions resulting in appreciable death rates. A mathematical model of an adsorbed cell type ICR is presented in which a steady-state viable cell fraction is predicted, based on the assumptions of no cell accumulation in the reactor and a random loss of cells from the reactor. Data on cell death rates, cell growth rates, and productivity rates as functions of temperature, substrate, and ethanol concentration for the lactose utilizing yeast K. fragillis were incorporated into this model. The steady-state reactor viable cell fraction as predicted by this model is a strong function of both temperature and ethanol concentration. For example, a stable 20% viable fraction of the immobilized cells is predicted in ICR locations experiencing continuous conditions of either 30 g/L ethanol at 40°C, or 95 g/L ethanol at 25°C. Steady-state ICR “plug flow” concentration profiles and column productivities are predicted at three operating temperatures, 20, 30, and 40°C using two different models for ethanol inhibition of productivity. These profiles suggest that the reactor operating temperature should be low if higher outlet ethanol concentrations are desired. Three reactor design strategies are presented to maximize the viable cell fraction and improve long-term ethanol productivity in ICR's: (1) reducing outlet ethanol concentrations, (2) rotating segments of an ICR between high and low ethanol environments, and (3) simultaneous removal of the ethanol produced from the reactor as it is formed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260361003
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    Physiological, biochemical, and mathematical studies of micro-aerobic continuous ethanol fermentation by Saccharomyces cerevisiae. I: Hysteresis, oscillations, and maximum specific ethanol productivities in chemostat culture (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 1006-1019 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The growth and metabolism of Saccharomyces cerevisiae was studied in steady-state chemostat cultures under conditions of scarce oxygen and excess glucose. The specific ethanol productivity and specific glucose uptake rate were stimulated by 50% within a narrow range of air/nitrogen mixtures to the fermentor. Fermentation was inhibited at slightly higher and lower air/nitrogen ratios, confirming similar results by previous investigators. This stimulation could not be caused by obvious mechanisms, such as the Pasteur or Crabtree effects. Since this maximum in the fermentation rate occurred in a steady-state chemostat and at a constant dilution rate, the ATP yield of the culture necessarily attained a minimum. Thus, changes in the energetic efficiency of growth or the degree of wasting of ATP were surmised. The steady-state biomass concentration at various oxygenation rates exhibited hysteresis phenomena. Ignition and extinction of the biomass concentration occurred as critical oxygen feed rates were passed. The hysteresis was prevented by adding yeast extract to or reducing the antifoam concentration in the medium. These medium alterations had the simultaneous effect of stimulating the fermentation rate, suggesting that ATP has a critical role in dictating the biomass concentration in micro-aerobic culture. Silicone polymer antifoam was found to stimulate glycerol production at the expense of ethanol production, having consequences for the energy generation and the biomass concentration of the culture.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260361006
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  • 120
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    Immobilization can improve the stability of hybridoma antibody productivity in serum-free media (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 1049-1055 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Hybridoma cells (S3H5/γ2bA2) were cultivated in spinner flasks with 1% serum media and serum-free media. Monoclonal antibody productivity was maintained in 1% serum media. However, cells in serum-free media showed a decrease in antibody productivity, and it completely disappeared in IMDM-based low protein medium. This loss of antibody productivity was not observed when the cells were immobilized in alginate beads. In fact, immobilization enhanced the specific MAb productivity.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260361010
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  • 121
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    Lipolytic activities of a lipase immobilized on six selected supporting materials (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 132-137 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Six different types of materials including PVC, chitosan, chitin, agarose, Sepharose, and Trisacryl were evaluated for their lipase-coupling efficiencies. Among those tested, chitosan yielded the highest amount of lipase (79 mg/mL packed gel) immobilized but with lowest oil hydrolytic activity (0.03 mg eq/mL gel). The amount of lipase immobilized was affected by the length of the hydrocarbon chain attached to the PVC matrix but not by the pore size of the supports used. On the other hand, the specific activity of the immobilized lipase was affected by the pore size but not by the chain length of the hydrocarbon attached to the support. After immobilization, the optimal reaction pH was shifted from 7.5 to 8.5 and the optimal reaction temperature from 35 to 45-55°C. Lipase immobilized on PVC exhibited higher thermal stability than that on agarose. The half-life of the PVC immobilized lipase operating at 30°C in a packed-bed reactor was estimated to be about 400 h.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350204
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  • 122
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    Enzymatic production of hydrogen peroxide and acetaldehyde in a pressure reactor (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 834-838 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Alcohol oxidase, an enzyme which exhibits relatively weak substrate specificity among short chain alcohols, forms the corresponding aldehyde and hydrogen peroxide as coproduct. The ability of alcohol oxidase from Pichia pastoris yeast to convert ethanol to acetaldehyde and hydrogen peroxide was examined in an oxygen pressure reactor under conditions, such that oxygen availability was sufficient to permit rapid catalysis. Hydrogen peroxide levels of ∼1.8/M (6% w/w) were attained in 2-3 h with 2.8 μM enzyme, corresponding to a productivity of ∼30 g peroxide/g enzyme. Optimal conditions (within equipment limitations) were 900 psi oxygen, 2.6M ethanol, at 4 °C. Similar levels of products were reached in the reactor using enzyme immobilized covalently on controlled pore glass and noncovalently on an anion exchange support. Recycle of covalently immobilized enzyme was not possible as a result of enzyme inactivation after a single run. Limited recycle of noncovalently immobilized enzyme was accomplished with substantial decreases in levels of product attainable on each cycle.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360813
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  • 123
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    Micromixing in fermentors: Metabolic changes in Saccharomyces cerevisiae and their relationship to fluid turbulence (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 854-864 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Even when microorganisms are grown in highly agitated fermentors, calculation predicts a mismatch between the microscale of the turbulence (where the smallest eddy is typically 50-300 μm diameter) and the cellular dimensions (1-5 μm). The cell thus spends substantial portions of time in an apparently stagnant eddy, depleted of nutrients. The local fluid microscales were measured in a laboratory fermenter to confirm this. Using S. cerevisiae in continuous culture, it is shown that the local microscales influence cell metabolism dramatically. The issues addressed in this study are thus micromixing and microsegregation of reactants and how they influence cell yield.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360816
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  • 124
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    Diffusional limitations of immobilized Escherichia coli in hollow-fiber reactors: Influence on 31P NMR spectroscopy (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 887-901 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Escherichia coli cells were immobilized and grown in hollow-fiber reactors allowing simultaneous NMR spectroscopy and perfusion with nutrient medium. The extent to which the cells were starved due to inadequate mass transfer was predicted using a mathematical model of reaction and diffusion. Reactors were experimentally characterized using 35S autoradiography to visualize spatial variations in protein synthesis rates and transmission electron microscopy to indicate spatial variations in cell morphology. Mass transfer limitations in reactors operated at 37 °C were shown to be severe, with regions of starved cells occupying up to 80% of the cell-containing region. Phosphorus-31 nuclear magnetic resonance (NMR) spectra of the immobilized, perfused cells revealed abnormally low volume-averaged concentrations of sugar phosphates, NTP, and ratios of NTP/NDP in these reactors. Intracellular pH was also depressed in the cells. In order to overcome mass transfer limitations in the cell layer, the reactor growth temperature was decreased. Sulfur-35 autoradiographs of a reactor operated at 16°C did not indicate the presence of starved cells. The NMR spectra obtained from this reactor showed near-normal intracellular pH, metabolite concentrations, and NTP/NDP ratios. The presence of significant mass transfer limitations in a perfused cell sample during NMR spectroscopy is generally undesirable since the resulting spectra can be ambiguous and difficult to interpret. The strategy adopted in this work, namely estimation of the relative rates of reaction and diffusion in the cell mass and appropriate changes in reactor design and operating parameters, should prove generally applicable for the design of perfused cell samples for NMR spectroscopic experiments.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360904
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    Masthead (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260351001
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  • 126
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    Enzyme loading in a solid support with nonuniform pore size distribution (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 976-982 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The concept of pore size distribution is incorporated into the Clark model of enzyme immobilization in the present study. This refined model predicted that in the case of small harmonic pore radius with the same surface area and porosity of the support, more enzyme could be loaded in a support with nonuniform pores than that with uniform pores. In comparing the enzyme loading efficiency of the support with two different pore size distributions, the one with Gaussian distribution had the greater amount of enzyme immobilized than the other one with Rajagopalan's distribution. Furthermore, more enzyme could be loaded in a support with wider Gaussian pore size distribution than that with narrower distribution. The immobilized enzyme profile in the solid support with pore size distribution displayed a stepwise pattern which differed appreciably from the sigmoidal profile predicted for the support with uniform pore size. This stepwise enzyme distribution profile became sigmoidal with decreasing hT or increasing k. The new model could be used for designing protocols for an enzyme immobilization process.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260351004
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  • 127
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    New method of immobilization of microbial cells by capture on the surface of insoluble pyridinium-type resin (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 1000-1005 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new method for the immobilization of microbial cells has been developed. Whole cells of Escherichia coli with aspartase activity were immobilized by capture on the surface of cross-linked poly(N-benzyl-4-vinylpyridinium bromide) containing styrene (BVPS resin), an insoluble pyridinium-type resin. When a suspension of the bacterial cells in buffer solution was passed through a glass column containing beads of BVPS resin, the cells were captured on the resin surface and formed an immobilized cell system. A fixed-bed column reactor containing 300 mg of the bacterial cells immobilized by capture on 10 g of BVPS resin beads was used for the preparation of L-aspartic acid from ammonium fumarate. Continuous operation of tne bioreactor produced L-aspartic acid in a quantitative yield when the influent substrate concentration was 0.1M and the flow rate was 0.41-0.83 bed volumes per hour at pH 7.4-7.7 at 30°C.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260351007
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  • 128
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    Effects of spatial heterogeneity on the dynamics of a microbial feeding interaction (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 1024-1033 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model for an ideal chemostat in which one microbial population feeds on another and where Monod's model is used for the specific growth rates of both populations predicts a less stable behavior for the system than the one observed experimentally. Various factors have been proposed as being the reason for the increased stability of such systems. In this work, the effect of spatial heterogeneity on the dynamics of the microbial feeding interaction is studied. It is concluded that spatial heterogeneity has a stabilizing effect on the system. This effect combined with other factors could be the reason for the increased stability observed in systems where a microbial feeding interaction occurs.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260351010
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  • 129
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    Use of an oxygen microsensor for the determination of intrinsic kinetic parameters of an immobilized oxygen reducing enzyme (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 1078-1087 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An oxygen microsensor was used to measure internal oxygen profiles in biocatalyst particles of different diameter and activity. The particles were made of agarose gel and contained an oxygen reducing enzyme, L-lactate mono-oxygenase. The kinetics of the enzyme could be well described by the Michaelis-Menten equation. From the internal substrate concentration profile the intrinsic kinetic parameters were determined by means of fitting a simulated profile to the measurements, using Marquardt's algorithm. The intrinsic kinetic parameters found following this procedure appeared to be independent of particle radius or enzyme loading used, proving the method to be reliable. These parameters were also compared with the kinetic parameters of the free enzyme which were determined in a biological oxygen monitoring system. The intrinsic kinetic parameters showed a decrease with a factor 2.3 for Vm value and with a factor 2.7 for the Km value compared to the parameters for the free enzyme. From this the conclusion can be drawn that the immobilization as such or the carrier material not only can have an effect on the maximum intrinsic conversion rate (Vm) but also on the affinity of the enzyme (Km) for oxygen.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260351103
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  • 130
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    Production of S-adenosyl-L-methionine by Saccharomyces cerevisiae cells carrying a gene for ethionine resistance (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 1120-1124 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A gene for ethionine resistance isolated from the yeast Saccharomyces cerevisiae DKD-5D-H conferred on the yeast cells resistance to seleno-L-methionine and capability to produce S-adenosyl-L-methionine in the cells. An enzymatic study of the L-methionine synthetic pathway of L-methionine proto- and auxotrophs and in dried yeast cells with or without the gene suggested that the cloned gene for ethionine resistance is responsible for the activity of S-adenosyl-L-methionine synthase. To produce S-adenosyl-L-methionine by yeast cells transformed with the ethionine resistance gene, some culturing conditions were determined.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260351107
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    Increased mass transfer to microorganisms with fluid motion (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 1135-1144 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of fluid flow and laminar shear on bacterial uptake was examined under conditions representative of the fluid environment of unattached and attached cells in wastewater treatment bioreactors. Laminar shear rates below 50 s-1 did not increase leucine uptake by suspended cultures of Zoogloea ramigera. However, leucine uptake by cells fixed in a flow field of ∼ 1 mm s-1 was 55-65% greater than uptake by suspended cells. Enhanced microbial uptake with advective motion is consistent with mass transfer rates calculated using Sherwood number correlations. Advective flow increases microbial uptake by increasing collisions between substrate molecules and cells through compression of the concentration boundary layer surrounding a cell. The rate of leucine uptake suggests that binding proteins used to transport leucine into the cell can occupy approximately 1% of the cell surface area.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260351109
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  • 132
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    Quantitative assay for low levels of L-threonine in amino acid fermentation broths (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 1169-1173 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260351115
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  • 133
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    Production of recombinant human growth hormone in Escherichia coli: Expression of different precursors and physiological effects of glucose, acetate, and salts (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 1-11 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The constitutive cytoplasmic expression in E. coli of human growth hormone (hGH) with different N-terminal extensions (3 or 4 amino acids) has been studied. These hGH precursors were used for in vitro cleavage to obtain the mature, authentic hormone. Small changes in the amino acid extensions of the hGH precursors led to three-fold differences in specific expression rates. The specific expression rate of the hGH precursors was inversely proportional to the ratios of the specific growth rates of plasmid containing and plasmid free cells (μ+/μ-) and also to the genetic stability. To ensure a satisfactory genetic stability in production fermentors, an hGH precursor with a moderate expression efficiency was chosen.The medium composition and growth conditions were studied, resulting in the choice of a glucose fed batch fermentation process using a complex medium. In this process a yield of 2000 mg/L of met-ala-glu-hGH (MAE-hGH) was obtained. The fermentation process comprised a glucose-limited growth phase followed by a second phase with increased glucose feed and exhaustion of phosphate from the medium. The second phase is characterized by an MAE-hGH production, whereas further biomass formation is blocked. High concentrations of glucose led to reduced specific expression of MAE-hGH - the specific and total yield in batch glucose fermentations is only about 30% of the yield in optimized fed batch fermentations. The physiological background for this was investigated. Chemostat experiments showed that the glucose concentration and the metabolic condition of the cells - i.e. with or without formation of acetate - was not critical per se in order to obtain a high specific yield of MAE-hGH. Therefore it is unlikely that formation of MAE-hGH is catabolite repressed by glucose. Furthermore it was shown that the specific production rate of MAE-hGH was independent of the specific growth rate and it was further demonstrated that the decrease in expression efficiency in glucose batch fermentation was a result of an inhibitory effect of acetic acid. In batch fermentations this inhibitory effect was enhanced by a salt effect caused by increased consumption of acid and base used to control pH. The identity of the acid and the base used are not important in this context.From studies of the expression of other proteins in E. coli. with constitutive as well as inducible promoters we conclude that glucose fed batch processes are often superior to batch processes in the production of heterologous proteins E. coli.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260360102
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    Production of L-phenylacetyl carbinol by immobilized yeast cells: I. Batch fermentation (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 47-54 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Immobilization of Saccharomyces cerevisiae ATCC 834 within alginate beads enhances microbiological conversion of benzaldehyde to L-phenylacetyl carbinol (L-PAC), a precursor employed for synthesis of L-ephedrine. Yields of 90% L-PAC on benzaldehyde (initially 0.6% in medium) were obtained with immobilized cells, in contrast to about 10% with free cells which tend to form pellets in the presence of benzaldehyde. The predominant favorable action of immobilization appears to be a reduction in the toxic or inhibitory effects of benzaldehyde. With an initial benzaldehyde concentration of about 0.6% in the medium the optimum cell mass concentration was observed to be about 28 g cell mass (immobilized) per liter of medium.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360107
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  • 135
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    Kinetics of CO2 hydration in fermentors: pH and pressure effects (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 92-96 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fluctuations in pH and head-space pressure in a fermentor introduce temporary changes in off-gas CO2 concentrations. These changes are quantified using a simple model based on kinetics of CO2 hydration and gas-liquid mass transfer. The model is verified experimentally. An eigenvalue analysis of the model indicates that mass transfer is the parameter which controls the dynamics of CO2 equilibration.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360112
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  • 136
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    Wall-Growth hollow-fiber reactor for tissue culture: II. A theoretical model (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 104-108 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360114
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    A comparison of mathematical model predictions to experimental measurements for growth and recombinant protein production in induced cultures of Escherichia coli (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 124-134 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Recombinant cell growth and protein synthesis by a recombinant Escherichia coli under various inducing conditions are compared to the predictions of a mathematical model. The mathematical model used was a combination of two literature models: (1) an empirical kinetic model for recombinant growth and product formation and (2) a genetically structured model of the lac promoter-operator on a multicopy plasmid. The experimental system utilized was recombinant E. coli CSH22 bearing the temperature-sensitive plasmid pVH106/172, which codes for the synthesis of β-galactosidase and the other lac operon genes under the control of a lac promoter. Mathematical model predictions for recombinant β-galactosidase yield and specific growth rate were compared with fermentation measurements of these same quantities for conditions of chemical induction with cyclic AMP and IPTG, copy number amplification (by shifting culture temperature), and combined chemical induction and copy number amplification. The model successfully predicted experimental product yields for most cases of chemical induction even though the product yields varied from 0.34 × 103 to 1500 × 103 units/g cell mass. The kinetic model also correctly predicted a decline in the specific growth rate with increasing levels of plasmid and recombinant protein. The model was less successful at predicting product amplification at high copy numbers. A comparison of model predictions and experimental results was also used to investigate some of the assumptions used in constructing the mathematical models.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260360204
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  • 138
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    Continuous hydrolysis of oil by immobilized lipase in a countercurrent reactor (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 617-622 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Lipase from Pseudomonas fluorescens biotype I was immobilized by adsorption of anion exchange resin using glutaraldehyde to enhance the adsorption. The activity yield of the immobilized lipase was very low (below 1%) when lipase activity was measured using emulsion substrate. The activity yield was 10-70% when lipase activity was measured using non-emulsion substrate. Countercurrent reactors for hydrolysis of oil using non-emulsion substrate were studied. A fluidized bed reactor was found to be superior to a fixed bed one since in a fixed bed reactor the separation rate of the two layers was slow and the flow rate of the reactor had to be slower than the separation rate. A fluidized bed reactor system equipped with settling compartments and stirring compartments was devised. Continuous lipolysis at 60 °C and continuous separation of oily product and water soluble product were performed. After continuous operation for more than 3 months, 70% of the initial activity of the immobilized lipase was observed at the end of the reaction.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260360609
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  • 139
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    Continuous production of maltotetraose using a dual immobilized enzyme system of maltotetraose-forming amylase and pullulanase (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 790-796 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to produce a product with a high content of maltotetraose, dual-enzyme systems composed of immobilized maltotetraose-forming amylase (G4-forming amylase) and pullulanase were studied. The thermostability of individually immobilized enzymes was examined in continuous operation; studies revealed that the enzyme immobilized on “Chitopearl” was much more stable than that immobilized on Diaion HP-50. The effects of operating conditions on the stability of G4 forming amylase immobilized on “Chitopearl” were examined to confirm that the apparent half-life data could be arranged using the immobilized enzyme stability factor, fs. As for the dual immobilized enzyme system, six methods of usage were considered, with five yielding a 7-10% (w/w) higher content of maltotetraose product than the single-enzyme system. The effects of operating conditions on the maltotetraose production reaction were examined to confirm that the maltotetraose content of the products could be analyzed using the specific space velocity,SSV. In dual immobilized enzyme systems, pullulanase immobilized on the same carrier as the G4-forming amylase was found to be more stable than pullulanase immobilized on separate carriers. The effectiveness of using immobilized pullulanase along with the G4-forming amylase was confirmed from constant-conversion operations in which the maltotetraose content in the product was kept at 50% (w/w) in laboratory-scale experimentation.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260360806
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  • 140
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    The process utility of thermotolerant methylotrophic bacteria: II. An evaluation of transient responses (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 821-825 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In Part II, the process utility of a thermotolerant methylotrophic bacterium is evaluated with respect to its dynamic response when various substrate or nutrient pulses are imposed on it while growing under steady-state conditions in a chemostat. The pulses investigated were methanol pulses on methanol-, methanol/formaldehyde-, and dual methanol/ammonia-limited cultures and an ammonia pulse on a severely nitrogen (ammonia)-limited culture. The results obtained, although exemplifying the complex biochemistry of such bacteria, clearly demonstrate the bacteriums flexibility and versatility in handling process transients. Its lack of fastidiousness in unsteady state continuous culture make it a most promising candidate for inclusion in process cultures for elevated temperature industrial wastewater treatment.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360811
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  • 141
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    Masthead (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360901
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  • 142
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    A hollow-fiber reactor design for NMR studies of microbial cells (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 879-886 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A hollow-fiber membrane reactor was designed and constructed to allow perfusion of entrapped, dense Escherichia coli cells with nutrient medium during examination of cell metabolism using nuclear magnetic resonance (NMR) spectroscopy. Phosphorus-31 NMR spectra of the perfused cells included peaks for nucleoside di- and triphosphates, sugar phosphates, and pH-sensitive peaks for inorganic phosphate. The observed intensity of the lumenal inorganic phosphate peak was found to depend on flow rate, ruling out the use of this peak as a concentration reference. Absolute intracellular pH values obtained from NMR measurements were found to be accurate to 0.2 pH units due to uncertainties in intracellular ionic concentrations. Relative pH values, however, were found to be sensitive to cell energetic status. The response of E. coli intracellular pH following a shift to carbon starvation medium was monitored with a resolution of 3 min. Use of a hollow-fiber reactor for cell containment and perfusion during NMR spectroscopy enables metabolic experiments of longer duration and of greater variety than is possible using standard, nonperfused sample tubes.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260360903
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  • 143
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    The use of a metabolically structured model in the study of growth, nitrification, and denitrification by Thiosphaera pantotropha (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 921-930 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Thiosphaera pantotropha is capable of aerobic heterotrophic nitrification and both aerobic and anaerobic denitrification. These phenomena have been studied in acetate-limited aerobic and anaerobic continuous cultures supplied with ammonia and nitrate. The internal reaction rates were defined, based on biochemical knowledge. The observable external conversion rates are related through a linear equation on the basis of the specified internal reaction rates. The linear equation is a Pirt relation extended for microbial systems with multiple electron donors (acetate and ammonia) and electron acceptors (oxygen and nitrate). The coefficients in this equation were estimated from the continuous culture measurements, and are composed of parameters involved in ATP production and consumption by the microorganism. It is shown that with realistic values for these parameters, the metabolically structured model describes the aerobic as well as the anaerobic experiments.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260360907
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  • 144
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    Determination of growth and coupled nitrification/denitrification by immobilized Thiosphaera pantotropha using measurement and modeling of oxygen profiles (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 931-939 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An oxygen microsensor in combination with mathematical modeling was used to determine the behavior of immobilized Thiosphaera pantotropha. This organism can convert ammonia completely to nitrogen gas under aerobic conditions (coupled nitrification/denitrification) and denitrifies nitrate at highest rates under anaerobic conditions. Immobilization of T. pantotropha can result in aerobic and anaerobic zones inside the biocatalyst particle which will be advantageous for the conversion of ammonia and nitrate from wastewater. However, information of the effects of immobilization on the physiology of T. pantotropha is necessary for the development of such a system. This article gives the extension of a model developed to describe the behavior of chemostat cultures of T. pantotropha so that it can be used for immobilized cells. The original model was based on metabolic reaction equations. Kinetic and diffusion equations have now been added. Experimental verification was carried out using a stirred tank reactor and a Kluyver flask. After immobilization in agarose, the cells were grown in the particles under continuous culture conditions for 3 days. After 24 h the oxygen penetration depth showed a constant value of 100 μ, indicating that a steady state was reached. Scanning electron micrographs showed that large colonies of cells were present in this 100-μm aerobic layer.From the dynamics of the start-up phase, several parameters were determined from measurements of the oxygen concentration profiles made every few hours. The profiles simulated by the model were fitted to the measured data. The average value for the maximum specific growth rate was 0.52 h-1, and the maximum oxygen conversion rate was 1.0 mol Cmol-1 h-1. The maximum specific acetate uptake rate was 2.0 mol Cmol-1 h-1, and the Monod constant for acetate was 2.9 × 10-2 mol m-3. The maximum specific nitrification rate was 0.58 × 10-1 mol Cmol-1 h-1, and the amount of oxygen necessary for nitrification was 11% of the total oxygen uptake rate. Most of the kinetic parameters determined for the immobilized cells were in good agreement with those for the suspended cells. Only the maximum specific growth rate was significantly higher, and the maximum specific nitrification rate was some what lower than for suspended cells. The experimental results clearly show that an oxygen microsensor, in combination with mathematical modeling, can successfully be used to elucidate the kinetic behavior of immobilized, oxygen-consuming, cells.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260360908
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  • 145
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    The long-term effects of ethanol on immobilized cell reactor performance using K. fragilis (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 975-982 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of ethanol on reactor performance were studied in a small, 5-cm packed height, “differential” type immobilized cell reactor. Lactose utilizing yeast cells, Kluyveromyces fragilis, were absorbed to a porous adsorbant sponge matrix in a gas continuous reactor. Step changes in the feed ethanol concentration to the column (10-130 g/L) were used to test the reactor response over extended periods of time (about 30-50 h per dosage level) followed by a return to basal zero inlet ethanol feed. Effluent cell density and effluent cell viability were measured at intervals. An inhibitory response in ethanol productivity to feed dosage ethanol levels above 20 g/L was detected almost immediately, with a near steady state response noted within 2.5 h of initiating the dosage. Feed ethanol levels above 50 g/L resulted in a subsequent gradual decrease in reactor productivity over time, which was associated with a decrease in the fraction of viable shed cells in the reactor effluent. The reactor response to a step removal of the ethanol inhibition was also monitored. Quick and complete rebounding of the fermentation rate to the original basal rate was noted following dosage concentrations of under 50 g/L ethanol. Recovery rates slowed following ethanol dosage levels above 50 g/L. Viable shed cell density improved overtime during the slow recovery periods. Growth rates (as determined by shed cell density) were more strongly inhibited than productivity. Growth responded more slowly to changes in ethanol environment as growth rates at 30 h fell to about 40% of the rates measured 7.5 h after initiation of a dosage level. It is concluded that ethanol contributions to cell injury and death (and consequent ICR performance degradation) may be more important than ethanol inhibition of productivity rates in the long-term operation of immobilized cell reactors at ethanol concentrations over 50 g/L.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260361002
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  • 146
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    Masthead (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260361101
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  • 147
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    Characterization of E. coli cell disintegrates from a bead mill and high pressure homogenizers (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 1083-1089 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The protein releases, the particle size distribution and the viscosity of disrupted E. coli suspensions from Dyno Mill KDL, Manton Gaulin 15 M-8TA and Microfluidizer M-110 were determined. The effects of these parameters on separation of the cell debris from the protein solution by centrifugation and by filtration were also examined. All three disintegration methods investigated give approximately the same protein and enzyme releases but considerably different physical properties of the cell disintegrates which influences centrifugation and filtration. The separation degree of biomass during centrifugation is only slightly affected by increasing degree of disruption (increasing protein releases) in the bead mill, while an increase in the degree of disruption in the two high pressure homogenizers drastically reduces the centrifugal degree of separation. However, increasing degrees of disruption result in shorter filtration times during filtration for all three disintegration methods. The results show further that the cell concentration only has a minor influence on protein releases in the Microfluidizer high-pressure homogenizer, while an increase in the biomass content reduces the separability of the cell disintegrate both in filtration and in centrifugation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260361102
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  • 148
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    Enhancing penicillin fermentations by increased oxygen solubility through the addition of n-hexadecane (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 1110-1118 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: n-Hexadecane was added to fermentation media to increase the medium oxygen solubilities, thus enhancing oxygen transfer rates in penicillin fermentations. For shake flask fermentations, cells were found to grow faster in the flasks with n-hexadecane than those without. The addition of n-hexadecane to penicillin fermentations was shown to significantly increase cell growth and penicillin production and reduce formation of mycelial pellets. The result was attributed to the enhancement of oxygen transfer in mycelial fermentations due to the higher oxygen solubilities of fermentation media achieved by adding n-hexadecane.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260361106
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  • 149
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    A comparison of the Michaelis-Menten and HCH-1 models (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 1151-1154 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260361110
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  • 150
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    The use of a single-fiber reactor for the enzymatic removal of amino acids from solutions (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 260-267 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this article we describe the use of bench-scale single-fiber dialyzers for the development and testing of an immobilized enzyme reactor for the treatment of leukemia. The treatment is based on the enzymatic removal of specific amino acids from the blood of leukemia patients. L-Lysine α-oxidase and catalase were coimmobilized within the void space of the porous region of asymmetric hollow-fiber membranes for the removal of L-lysine from simulated human plasma solutions. Hollow-fiber reactor performance was evaluated using a small single-fiber dialyzer (SFD) consisting of a single fiber encased in a protective glass shell. This small reactor affords ease of use, requires small amounts of chemicals and biochemicals, and gives useful reactor performance data. Single-fiber dialyzers were constructed using polyamide fibers with a molecular weight cutoff of 10,000 (PA10 fibers); these fibers demonstrated the best compatibility with and retention of the enzymes. The SFD performance in removing L-lysine from solution was evaluated under both steady and pulsatile flow operation. Pulsatile flow was tested for two reasons: (1) to enhance the radial mass transfer of lysine within the SFD and (2) to simulate the pulsatile flow of blood in dialysis treatment. The use of pulsatile flow increased lysine conversion by 15% over the steady-flow case. Approximately 40% of the lysine was removed from simulated plasma by the SFD in a 4-h experiment using pulsatile flow in the recycle mode.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350307
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  • 151
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    Mass transfer phenomena in an airlift reactor: Effects of solids loading and temperature (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 483-491 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Gas holdups and volumetric mass transfer coefficients were measured in a concentric tube airlift reactor designed for the microbial desulfurization of coal. The solutions studied were comprised of an acidified basal salts solution containing thirteen different weight percentages (0 to 40) of coal (74 μm Ohio #1) at three different temperatures (30, 50, and 72°C). Gas holdup ∊G decreased with solids loading for the entire range studied. An enhancement in the volumetric mass transfer coefficient KLa with respect to that in pure solution was observed from zero to approximately 5 wt % (solids volume fraction ∊s = 0.035), the maximum enhancement occurring at approximately 2 wt % (∊s = 0.014). At higher solids fractions, the mass transfer coefficient decreased with further solids additions. Gas holdups and the mass transfer coefficients increased with temperature over the studied range. The KLa and ∊G were correlated to three process variables separately and the separate correlations combined to yield generalized correlations for the mass transfer coefficient and gas holdup for this system. The correlations may be used for design, operation, and ost estimation of such systems.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350506
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  • 152
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    An ESR study of spin-labeled silk fibroin membranes and spin-labeled glucose oxidase immobilized in silk fibroin membranes (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 511-517 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article describes the characteristics of silk fibroin membranes and glucose oxidase, immobilized in membranes as determined by a variety of physical methods, mainly the spin-label electron spin resonance (ESR) method. The properties of membranes insolubilized by different methods, i. e., immersion in 80% methanol aqueous solution, uniaxially drawing by placing on a stretcher, and hydration by placing in a desiccator of 96% relative humidity (RH) for 17 h, are compared. The results are also analyzed in relation to ESR spectra of spin-labeled immobilized glucose oxidase and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy as a model of the substrate. It is concluded that the heterogeneous structures of the swollen membranes in water differ locally among membranes insolubilized by different methods, but the immobilized state of the enzyme in such membranes is mostly similar. This is correlated to the fact that the thermal or pH stabilities are essentially same among glucose-oxidase-immobilized silk fibroin membranes insolubilized by different methods.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350509
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  • 153
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    Microbial control of the production of hydrogen sulfide by sulfate-reducing bacteria (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 533-539 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A sulfide-resistant ctrain of Thiobacillus denitrificans, strain F, prevented the accumulation of sulfide by Desulfovibrio desulfuricans when both organisms were grown in liquid medium or in Berea sandstone cores. The wild-type strain of T. denitrificans did not prevent the accumulation of sulfide produced by D. desulfuricans. Strain F also prevented the accumulation of sulfide by a mixed population of sulfate-reducing bacteria enriched from an oil field brine. Fermentation balances showed that strain F stoichiometrically oxidized the sulfide produced by D. desulfuricans and the oil field brine enrichment to sulfate. These data suggest that strain F would be effective in controlling sulfide production in oil reservoirs and other environments.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260350512
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  • 154
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    Drying of ethanol vapors by adsorption on corn meal (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 598-608 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experiments have been carried out on a laboratory-scale adsorber packed with 3.3 kg cornmeal. The effects of varying particle size, feed concentrations and flow rates, and regeneration conditions on the product quality and breakthrough times were investigated. It was found that 85% (w/w) vapor feed gave the best product, and product yields of up to 99.8% (w/w) alcohol were obtained at energy costs as low as 4.0 MJ kg-1. It is suggested how this figure could be improved.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350607
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  • 155
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    Oxygen transfer enhancement in aqueous/perfluorocarbon fermentation systems: II. theoretical analysis (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 586-597 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two theoretical approaches were examined to quantify observed experimental oxygen transfer enhancements in aqueous/perfluorocarbon (pfc) fermentation systems. Steady-state macroscopic balance results indicated that enhancements in the presence of reaction were a function of the gas bubble-to-droplet diameter ratio for pfc-in-water dispersions, but primarily a function of only the droplet diameter for water-in-pfc dispersions. The problem of unsteady-state diffusion into a semi-infinite composite medium was employed to predict enhancements in the absence of reaction based on the relative permeabilities of the perfluorocarbon and water phases. Since potential enhancements exceeded actual enhancements in the presence of an oxygen consuming reaction for water-in-pfc dispersions, the use of less expensive, lower oxygenpermeable oil phases is recommended in practice.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350606
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  • 156
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    Immobilization of biocatalysts by photochemically grafted membranes: some studies with catalase as model systemPart 13 of the series “Photosynthetic Membranes.”. (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 646-649 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350610
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  • 157
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    Multipoint attachment to a support protects enzyme from inactivation by organic solvents: α-Chymotrypsin in aqueous solutions of alcohols and diols (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 653-659 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Inactivation of α-chymotrypsin in aqueous solutions of alcohols and diols proceeds both reversibly and irreversibly. Reversible loss of the specific enzyme activity results from conformational changes (unfolding) of the enzyme detected by fluorescence spectroscopy. Multipoint covalent attachment to the matrix of polyacryl-amide gel by copolymerization method stabilizes α-chymotrypsin from denaturation by alcohols, the stabilizing effect increasing with the number of bonds between the protein and the support. Immobilization protects the enzyme also from irreversible inactivation by organic solvents resulting from bimolecular aggregation and autolysis.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350702
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  • 158
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    Production of indole alkaloids by surface immobilized C. roseus cells (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 660-667 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A technique was developed to surface immobilize plant cells and was scaled up in laboratory size bioreactors. This technique was shown not to hinder the biosynthetic potential of Catharanthus roseus immobilized cells and to induce a partial release (300 μg/L) of serpentine into the culture medium contrary to suspension cultured cells. The release pattern seemed to follow the biosynthesis trends of the product. This release mechanism could be stimulated by a factor of 10 within 2 h by increasing the pH of the culture from 5.0 to 5.5.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260350703
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  • 159
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    Plasmid-encoded protein: The principal factor in the “metabolic burden” associated with recombinant bacteria (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 668-681 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experimental elucidation of the metabolic load placed on bacteria by the expression of foreign protein is presented. The host/vector system is Escherichia coli RR1/pBR329 (ampr, camr, and letr). Plasmid content results, which indicate that the plasmid copy number monotonically increases with decreasing growth rate, are consistent with the literature on ColE1-like plasmids. More significantly, we have experimentally quantified the reduction in growth rate brought about by the expression of chloramphenicol-acetyl-transferase (CAT) and β-lactamase. Results indicate a nearly linear decrease in growth rate with increasing foreign protein content. Also, the change in growth rate due to foreign protein expression depends on the growth rate of the cells. The observed linear relationship is media independent and, to our knowledge, previously undocumented. Furthermore, the induction of CAT, mediated by the presence of chloramphenicol, is shown to occur only at low growth rates, which further increases the metabolic load.Results are vdelineated with the aid of a structured kinetic model representing the metabolism of recombinant E. coli. In this article, several previous hypotheses and model predictions are justified and validated. This work provides an important step in the development of comprehensive, methabolically-structured, kinetic models capable of prediciting optimal conditions for maximizing product yield.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260350704
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    Development of a biosensor for assaying postmortem nucleotide degradation in fish tissues (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 739-745 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An enzyme sensor system has been developed to assess the freshness level in fish tissue. The system was designed to measure the K value, the concentration ratio of [Hx + HxR] and [Hx + HxR + IMP], where Hx, HxR, and IMP are hypoxanthine, inosine and inosine-5′-monophosphate, respectively. The [Hx + HxR] concentration in tissue extract was measured by nucleoside phosphorylase and xanthine oxidase immobilized on a preactivated nylon membrane and attached to the tip of a polarographic electrode. The electrode amperometrically detected the products of degradation, hydrogen peroxide and uric acid. For determination of [IMP + HxR + Hx], IMP was first converted to HxR by nucleotidase immobilized on the wall of a polystyrene tube. The enzyme electrode consisting of nucleoside phosphorylase and xanthine oxidase provided excellent reproducible results for at least 40 repeated assays and immobilized nucleotidase was good for at least 40 assays as well. The K value for each sample could be determined in ca. 10 min. When applied to K value measurements in several fish meats, the results obtained agreed well with those obtained by the conventional enzymatic method.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350712
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  • 161
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    Simple constrained-optimization view of acetate overflow in E. coli (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 732-738 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The production of acetate by aerobically growing E. coli is examined. The problem is formulated in terms of a flow network that has as its objective maximal ATP synthesis. It is found that when loads are imposed and flux constraints exist either at the level of NADH turnover rate or the activity of a key Krebs cycle enzyme, switching to acetate overflow is predicted. Moreover, the result found for the latter constraint can be shown to be formally equivalent to a correlation experimentally determined for the specific rate of acetate production by E. coli K-12.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260350711
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  • 162
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    Masthead (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350801
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  • 163
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    The effect of agitation on the morphology and penicillin production of Penicillium chrysogenum (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 1011-1023 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Penicillium chrysogenum strain P1 was grown on complex media in 10 and 100 L agitated fermenters at various aeration rates and stirrer speeds. Samples were removed at intervals for measurements of the culture morphology. At high stirrer speeds (1000 and 1200 rpm) in 10-L fermentations the rate of decrease in the mean effective hyphal length was faster and the rate of penicillin production was lower than fermentations done at 800 rpm. At similar power inputs per unit volume in 100-L fermentations, the change in mean effective hyphal length was less and higher penicillin production rates were observed. This work comparing the results at two scales has shown that neither of the concepts of impeller tip speed or the dissipation rate of turbulence have general validity as a measure of hyphal damage. Our results are reasonaby well correlated by groups similar to circulation rate (NDi3/V) with lower circulation rates being beneficial. An adaptation of the van Suijdam and Metz relationship, expressed as P/Di3tc, was most successful. Our data are insufficient to demonstrate the generality of the relationship but do support the concept of a dispersion zone around the impellers in which mycelia may be damaged. The greater the frequency of circulation of mycelia through the zone the greater the damage and the lower the rate of penicillin synthesis by the culture.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260351009
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  • 164
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    Development of a strategy to control the dissolved concentrations of oxygen and carbon dioxide at constant shear in a plant cell bioreactor (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 1088-1101 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To examine the effects of volatile components on plant cell growth, a bioreactor control system was developed to simultaneously control the dissolved concentrations of both oxygen and carbon dioxide. The first step in this work was to develop a mathematical model to account for gas-liquid mass transfer; biological utilization and production of O2 and CO2; and the series of chemical reactions of CO2 in water. Using this model and dynamic measurements for dissolved O2 and CO2, it was observed that (1) both absorption and desorption of a volatile component could be described by a single mass transfer coefficient, Kla, and (2) Kla values for oxygen and carbon dioxide transfer were directly proportional. The second step of this work was to employ the mathematical model in an adaptive feed-forward strategy to control the dissolved O2 and CO2 concentrations by manipulating the inlet gas composition to the bioreactor. This strategy allowed dissolved concentrations to be controlled without the need for changing either the total gas flow rate or agitator speed. Adaptive control was required because the volumetric rates of O2 and CO2 consumption and production vary with time during long term operation and therefore these rates must be continually updated. As the final step, we demonstrated that this control strategy was capable of controlling the dissolved gas concentrations in both short- and long-term studies involving the cultivation of Catharanthus roseus plant cells.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260351104
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  • 165
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    Degradation kinetics of pentachlorophenol by Phanerochaete chrysosporium (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 1125-1134 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The extracellular enzymes and cell mass from the pregrown Phanerochaete chrysosporium cultures were used for the degradation of PCP. The use of both extracellular enzymes and cell mass resulted in extensive mineralization of PCP, while the action of only the crude extracellular enzymes led to the formation of a degradation intermediate (TCHD). A kinetic model, which describes the relationship among PCP degradation, initial PCP concentration, dosage of extracellular enzymes, and cell mass concentration, was developed. Based on this model, various effects of initial PCP concentration, dosage of extracellular enzymes, and cell mass concentration were evaluated experimentally. It was found that when initial PCP concentration is lower than 12 μmol/L, the model of a parallel-series first-order reaction is sufficient to describe the degradation process. PCP disappearance and mineralization were enhanced by increasing either the extracellular enzyme concentration or the cell mass concentration. As high as 70% of PCP mineralization could be obtained by using a higher dosage of extracellular enzymes and cell mass. Various parameters of the kinetic model were determined and the model was verified experimentally. Simulation using this model provided the criteria needed to choose rational dosages of extracellular enzymes and cell mass for the degradation of PCP. Data reported allow some insight into the function of the extracellular enzymes and cell mass of P. chrysosporium in degradation processes of toxic pollutants and assist in the design and evaluation of practical bioremediation methods.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260351108
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    Effect of operating parameters on specific production rate of a cloned-gene product and performance of recombinant fermentation process (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 287-295 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A two-stage continuous system in combination with a temperature-sensitive expression system were used as model systems to maximize the productivity of a cloned gene and minimize the problem associated with the plasmid instability for a high-expression recombinant. In order to optimize the two-stage fermentation process, the effects of such operational variables as temperature and dilution rate on productivity of cloned gene were studied using the model systems and a recombinant, Escherichia coli K12 ΔH1 Δtrp/pPLc23trp A1. When the expression of cloned gene is induced by raising the operating temperature above 38°C, a significant decrease in the colony-forming-units (CFU) of the plasmid-harboring cell was observed, and the decrease was related to the product concentration. In order to describe this phenomenon, a new kinetic parameter related to the metabolic stress (metabolic stress factor) was introduced. It is defined as the ratio of the rate of change of pheno-type from colony-forming to non-colony-forming cells to the product accumulation per unit cell mass. At a fixed temperature of 40°C, the varying dilution rate D in the range of 0.35-0.90 h-1 did not affect the metabolic stress factor significantly. At a fixed dilution rate of D = 0.35 h-1, this factor remained practically constant up to 41°C but increased rapidly beyond 41°C. The effects of temperature and dilution rate in the second stage on the specific production rate were also studied while maintaining the apparent specific growth rate (μ2app) of the second stage constant at or near μ2app = 0.26 h-1. Under a constant dilution rate, D2 = 0.35 h-1, the maximum specific production rate obtained was about qp, max = 38 units TrpA/mg cell/h at 41°C. At a constant temperature, T2 = 40°C, specific production rate increased with decreasing dilution rate with in the dilution rate range of D2 = 0.35-0.90 h-1. Based on the results of our study, the optimal operating conditions found were dilution rate D2 = 0.35 h-1 and operating temperature T2 = 41°C at the apparent specific growth rate of 0.26 h-1. Under the optimal operating conditions, about threefold increase in productivity was achieved compared to the best batch culture result. In addition, the fermentation period could be extended for more than 100 h.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350310
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    Optimal control of biomass growth in a mixed culture (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 349-355 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is shown that, in a mixed culture, under realistic assumptions, the optimal temperature profile maximizing the final biomass production under the constraint of the final relative proportions of the two populations is constant. This result is illustrated with a simulation experiment on a lactic fermentation model.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350404
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  • 168
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    Comparison of wild-type and Reg 1 mutant saccharomyces cerevisiae metabolic levels during glucose and galactose metabolism using 31P NMR (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 395-407 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The reg 1 mutation will allow the expression of a cloned gene on a plasmid under the control of a GAL promoter in the presence of glucose. The metabolism of wild-type and reg l mutant strains was examined by in vivo 31P nuclear magnetic resonance (NMR) spectroscopy. Transient profiles of glucose 6-phosphate, fructose 6-phosphate, fructose 1, 6-diphosphate, and 3-phosphoglycerate indicated that glucose was processed differently for the reg 1 strain despite similar cytoplasrnic pH values and ATP levels. Intracellular phosphate became depleted in the transition to quasi-steady state and limited glycolysis in the reg 1 strain. The glucose uptake step or hexokinase step appears to be altered in the reg 1 strain. The reg 1 strain utilized galactose faster than the wild-type strain under the conditions used for NMR analysis. These results are consistent with the hypothesis that the REG 1 product operates early in the regulatory circuitry for glucose repression. This study illustrates the usefulness of transient information provided by NMR in understanding changes in the metabolism of genetically manipulated organisms.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350407
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  • 169
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    Mechanism of enhanced oxygen transfer in fermentation using emulsified oxygen-vectors (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 427-435 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Limitations of oxygen transfer in fermentation can be solved using auxiliary liquids immiscible in the aqueous phase. The liquids (called oxygen-vectors) used in this study were hydrocarbon (n-dodecane) and perfluorocarbon (forane F66E) in which oxygen is highly soluble (54.9 mg/L in n-dodecane and 118 mg/L in forane F66E at 35°C in contact with air at atmospheric pressure). It has been demonstrated that the use of n-dodecane emulsion in a culture of Aerobacter aerogenes enabled a 3. 5-fold increase of the volumetric oxygen transfer coefficient(kLa) calculated on a per-liter aqueous phase basis. The droplet size of the vector played a crucial role in the phenomena. When a static contact between gas bubble and vector droplet was established in water, the vector covered the bubble, in agreement with positive values of the spreading coefficient for these fluids. The determination of the oxygen transfer coefficients (kL) in a reactor with a definite interfacial area enabled the main resistance to be located in the boundary layer of the waterside either for a gas-water or a vector-water interface. Because oxygen consumption by weakly hydrophobic cells can only occur in the aqueous phase, the oxygen transfer is achieved according to the following pathway: gas-vector-water-cell. Finally, a mechanism for oxygen transfer within this four-phased system is proposed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350410
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  • 170
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    A thermodynamic model to predict Phanerochaete chrysosporium INA-12 adhesion to various solid carriers in relation to lignin peroxidase production (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 477-482 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A thermodynamic model was used in this study to predict the adhesion of Phanerochaete chrysosporium INA-12 as conidiospores or mycelium to various solid carriers. Theoretical predictions were closely reflected by experimental results. Amount of immobilized mycelium was higher for hydrophobic (polypropylene and polyurethane) than for hydrophilic carrier (stainless steel and grey). Lignin peroxidase production was stimulated in the same way. However, better results were obtained with polyurethane than with polypropylene and with grey than with stainless steel. These results were attributed to roughness effects of solid surfaces. Surface morphology characterization showed that the surface roughness parameter RA was higher for polyurethane and grey as compared to polypropylene and stainless steel, respectively. On the other hand, polyurethane is not simply rugous; it has an intraparticle porosity as well as a higher total surface area as compared to polypropylene.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350505
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  • 171
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    Protease immobilization onto polyacrolein microspheres (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 518-524 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Water-insoluble proteases were prepared by immobilizing papain and chymotrypsin onto the surface of polyacrolein microspheres with and without oligoglycines as spacer. The activity of immobilized proteases was found to be still high toward small ester substrates, but very low toward casein, a high-molecular-weight substrate. The relative activity of the immobilized proteases without spacer decreased gradually with the decreasing surface concentration of the immobilized proteases on the microspheres. On the contrary, the immobilized proteases with oligoglycine spacers gave an almost constant activity for the substrate hydrolysis within the surface concentration region studied and gave a much higher relative activity than those without any spacer. With the longer spacer, the immobilized enzymes showed a higher activity toward casein hydrolysis, whereas there was an optimum length for the spacer when hydrolysis was carried out toward the low-molecular-weight substrate. The thermal stability of the immobilized proteases was higher than that of the respective native proteases. The initial enzymatic activity of the immobilized proteases maintained almost unchanged without any elimination and inactivation of proteases, when the batch enzyme reaction was performed repeatedly, indicating the excellent durability.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350510
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  • 172
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    Liquid circulation in external-loop airlift bioreactors (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 540-546 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A simple model for prediction of liquid velocity in external-loop airlift bioreactors has been developed. Theoretical correlations for friction factor of gas-non-Newtonian two-phase flows and for liquid velocity in the riser were derived using the concept of an eddy diffusivity. The predictions of the proposed model were compared with the available experimental data for the friction factor and the liquid velocity in the riser of external-loop airlift contactors. Satisfactory agreement was obtained.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350513
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    Propagation of an amplifiable recombinant plasmid in Saccharomyces cerevisiae: flow cytometry studies and segregated modeling (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 565-577 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Efficient expression of a foreign protein product by the yeastSaccharomyces cerevisiaerequires a stable recombinant vector present at a high number of copies per cell. A conditional centromere yeast plasmid was constructed which can be amplified to high copy number by a process of unequal partitioning at cell division, followed by selection for increased copy number. However, in the absence of selection pressure for plasmid amplification, copy number rapidly drops from 25 plasmids/cell to 6 plasmids/cell in less than 10 generations of growth. Copy number subsequently decreases from 6 plasmids/cell to 2 plasmids/cell over a span of 50 generations. A combination of flow cytometric measurement of copy number distributions and segregated mathematical modeling were applied to test the predictions of a conceptual model of conditional centromereplasmid propagation. Measured distributions of plasmid content displayed a significant subpopulation of cells with a copy number of 4-6, evenin a population whose mean copy number was 13.5. This type of copy number distribution was reproduced by a mathematical model which assumes that amaximum of 4-6 centromere plasmids per cell can be stably partitionedat cell division. The model also reproduces the observed biphasic kinetics of plasmid number instability. The agreement between simulation and experimental results provides support for the proposed model and demonstrates the utility of the flow cytometry/segregated modeling approach for the study of multicopy recombinant vector propagation.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260350604
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    Immobilized cell biocatalyst activation and pseudo-steady-state behavior: Model and experiment (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 609-629 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An intrinsic, unstructured model has been utilized to describethe startup dynamics of a continuous Caalginate-immobilized Zymomonas mobilis (ATCC 10988) fermentation. This model predicts, at least qualitatively, transients in the fermenter effluent glucose, ethanol, and biomass concentrations as well as radial gradients in immobilized-cell concentration and activity within the gelbiocatalysts. Predicted intrabiocatalyst gradients in immobilized-cell specific growth rate were used to calculate the corresponding gradients in intracellular RNA level based on a reported linear relationship between the two. Mathematical simulations of immobilized biomass concentration profiles and RNA content were verified using a novel, scanning microfluorimetry technique.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350608
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    Kinetics of carrot somatic embryo development in suspension cultureThis paper was presented at the 1988 Annual Meeting of the AIChE, Washington, DC, November 27-December 2, 1988. (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 781-786 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Somatic embryos in liquid culture can serve as a mass cloning system in a plant propagation program. A quantitative formulation of embryo development obtained from cell suspension cultures is used to develop a segregated kinetic model. The model is based on standard classification schemes as previously developed by plant physiologists. Dependent variables include carbohydrate concentrations (sucrose, fructose, and glucose) and biomass apportioned among the inoculum (free single cells, cell clusters), normal developmental stages, and aberrant cell and embryo types. Good agreement between the model and experimental results is indicated and allows for a rigorous approach to media optimization and reactor scaleup for embryo formation.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260350805
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  • 176
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    Heat transfer simulation in solid substrate fermentation (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 802-808 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model was developed and tested to simulate the generation and transfer of heat in solid substrate fermentation (SSF). The experimental studies were realized in a 1-L static bioreactor packed with cassava wet meal and inoculated with Aspergillus niger. A simplified pseudohomogeneous monodimensional dynamic model was used for the energy balance. Kinetic equations taking into account biomass formation (logistic), sugar consumption (with maintenance), and carbon dioxide formation were used. Model verification was achieved by comparison of calculated and experimental temperatures. Heat transfer was evaluated by the estimation of Biot and Peclet heat dimensionless numbers 5-10 and 2550-2750, respectively. It was shown that conduction through the fermentation fixed bed was the main heat transfer resistance. This model intends to reach a better understanding of transport phenomena in SSF, a fact which could be used to evaluate various alternatives for temperature control of SSF, i.e., changing air flow rates and increasing water content. Dimensionless numbers could be used as scale-up criteria of large fermentors, since in those ratios are described the operating conditions, geometry, and size of the bioreactor. It could lead to improved solid reactor systems. The model can be used as a basis for automatic control of SSF for the production of valuable metabolites in static fermentors.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350808
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  • 177
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    Optimization of a pellicular biocatalyst for penicillin G production by Penicillium chrysogenum (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 608-616 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A previously developed immobilization technique involving latex coatings on solid particulate supports was investigated further for penicillin G production by Penicillium chrysogenum. Several modifications were found to decrease the germination lag time, including a higher spore concentration, a thinner latex layer, an increased latex porosity, and a decreased drying time. This approach enabled the development of immobilized mycelial pellets within 2-3 days from the onset of biocatalyst preparation and incubation.A continuous immobilized-cell airlift bioreactor produced penicillin G in a series of runs in which the production phase lasted up to 30 days. The productivity of this system was 3-6 times greater than the productivity of the corresponding free-cell shake flask fermentation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360608
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    On-line monitoring of the viscosity in dextran fermentation using piezoelectric quartz crystal (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 636-641 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel viscous sensor utilizing AT-cut quartz crystal to monitor the viscosity of fermentation broth was developed. The sensor system was constructed from the piezoelectric quartz crystal fixed to the cell, exposing only one side of the quartz crystal electrode, an oscillating circuit, a peak level meter, and a personal computer. In order to investigate the characteristics of the sensor system, a sensor signal relating to the resonant resistance of the quartz crystal was measured using dextran solutions with different molecular weights. The linear relationship was obtained between the sensor signal and the (ρη)1/2 of the liquid, where ρ and η are the density and viscosity, respectively. The sensor signal was dependent not only on the viscosity of the liquid but also on the molecular weight of dextran, because dextran solution shows a non-Newtonian property. The sensor system was applied for the on-line monitoring of the viscosity in dextran fermentation. A good correlation was observed between the sensor signal and the viscosity value measured with a rotational viscometer for the fermentation broth. Little bubbling effect and agitation of the sensor signal were observed, showing that this system can be utilized for viscosity monitoring in a bioprocess.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360612
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  • 179
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    A structured kinetic model for Zymomonas mobilis ATCC10988 (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 694-704 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The inhibitory effects of glucose and ethanol on Zymomonas mobilis ATCC10988 were isolated through kinetic analysis of transient batch fermentation data. Growth of Z. mobilis was inhibited above a glucose concentration of 80 g/L. Growth was mildly inhibited by ethanol to 50 g/L, and severely inhibited above this concentration. Specific rates of ethanol production and glucose uptake were essentially invariant during batch fermentation. A structured kinetic model was developed, by way of augmentation of the Extended Bottleneck model, to quantify the kinetics of the growth and product formation processes. The model successfully describes the transient batch fermentation of Z. mobilis over a wide range of initial glucose concentration in a semidefined medium.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360707
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  • 180
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    A new biosensor for specific determination of glucose or fructose using an oxidoreductase of Zymomonas mobilis (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 744-749 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cells of Zymomonas mobilis were permeabilized with toluene in order to utilize the enzymes, glucose-fructose oxidoreductase and gluconolactonase, inside the intact cells. Permeabilized cells were immobilized in a gelatin membrane, and a whole cell enzyme electrode was constructed by fixing the membrane on pH electrode. The biosensor developed was used for specific determination of glucose or fructose by detecting the production rate of hydrogen ion. Optimum conditions for biosensor response were pH 6.2 and temperature of 39 °C. The biosensor was highly specific and reproducible, and calibration curves for glucose and fructose were excellent, being linear up to 5 and 50 g/L, respectively.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360713
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  • 181
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    The large-scale immobilization of Penicillium chrysogenum: Batch and continuous operation in an air-lift reactor (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 763-770 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A temperature-sensitive cell division cycle mutant of Penicillium chrysogenum P2 has been immobilized on Celite and grown in a 250-320-L working volume air-lift fermenter. The ability to uncouple growth and penicillin synthesis by raising the temperature to 30 °C also overcame the problem of the free cell mass which appeared after 300 h operation with the parent organism. After 500 h operation, penicillin and ACV dimer were still being synthesized.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360802
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  • 182
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    Changes in the activity of the general amino acid permease from Saccharomyces cerevisiae var. ellipsoideus during fermentation (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 808-810 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The evolution of the activity of the general amino acid permease and ethanol and glucose concentrations in the medium were studied in a mild fermentation process carried out by a wine strain of Saccharomyces cerevisiae var. ellipsoideus isolated from grape musts in spontaneous fermentation. The cells displayed a reduction in the activity of the general amino acid permease parallel to the increase of ethanol in the medium. This ethanol increase was not enough to promote a substantial inhibition on the total polypeptide synthesis measured as polyuridylic-acid-directed polyphenylalanine synthesis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360808
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  • 183
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    The process utility of thermotolerant methylotrophic bacteria: I. An evaluation in chemostat culture (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 816-820 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In Part l, the process utility of a thermotolerant methylotrophic bacterium is evaluated in chemostat culture under conditions where methanol, methanol/formaldehyde mixtures and dual methanol/ammonia limitation occurred. The results show that the bacterium studied was nonfastideous under steady-state operation, in contrast to results obtained in batch culture. For application in industrial wastewater treatment processes the bacterium should be employed in systems where the biomass residence time exceeds 5 h, i. e., dilution rates 〈 O.2 h-1. Under such conditions, methanol was essentially exhausted and the biomass yield coefficient was lowered.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360810
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  • 184
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    Growing Saccharomyces cerevisiae in calcium-alginate beads induces cell alterations which accelerate glucose conversion to ethanol (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 417-426 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Nongrowing Saccharomyces cerevisiae cells previously grown in alginate exhibit ethanol production rates 1.5 times greater than cells previously grown in suspension. Analysis of glucose, ethanol, and glycerol formation data using quasi-steady-state pathway stoichiometry shows that alginate-grown cells possess phosphofructokinase (PFK), ATPase, and polysaccharide synthesis maximum activities which are approximately two-, two-, and ninefold larger, respectively, than in suspension-grown cells. The estimated change in PFK maximum velocity is consistent with in vitro assays of PFK activity in extracts of suspension- and alginate-grown yeast. Estimation of ethanol production flux control coefficients using in vivo nuclear magnetic resonance (NMR) spectroscopy measurements of intracellular metabolite concentrations and a previously proposed detailed kinetic model of ethanol fermentation in yeast shows that glucose uptake dominates flux control in alginate-grown cells in suspension while earlier research revealed that PFK and ATPase exert significant flux control in suspension-grown cells. When placed in a calcium alginate matrix, alginate-grown cells produced ethanol 1.8 times more rapidly and accumulated substantially more polyphosphate than suspension-grown cells placed in alginate. Cells growing in alginate elicit responses at the genetic level which substantially alter pathway rates and flux control when these cells are used as either a suspended or an immobilized biocatalyst. These responses in gene expression to growth in alginate serve to reconfigure flux controls in alginate to a pattern which is similar to that obtained for suspended-grown cells in suspension.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360413
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  • 185
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    Recovery of a charged-fusion protein from cell extracts by polyelectrolyte precipitation (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 467-475 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: β-Galactosidase served as a model system to explore the feasibility of enhancing the selectivity of a low-cost, easily scaled separation method - precipitation. Enhanced selectivity was sought by fusing the enzyme with polypeptide tails including 5 and 11 aspartaies. The unfused protein could not be selectively removed from the Escherichia coli cell extract by precipitation with polyethylenimine (PEI), but the longest fusion could be selectively removed. The presence of nucleic acids limited the purification attainable. Pretreatment with nuclease followed by diafiltration resulted in an extract from which the same fusion could be precipitated with greater than fivefold enrichment, while the untailed enzyme remained unenriched by the same precipitation step. Selectivitiy is attributed to the binding strength of the polyanionic tails to the polycationic PEI.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360506
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  • 186
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    Trypsin purification by affinity binding to small unilamellar liposomes (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 506-519 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel protein purification process using affinity-ligand-modified liposomes and membrane ultrafiltration is described. The feasibility of the process was tested using trypsin as the model protein and p-aminobenzamidine (PAB) as the affinity ligand for trypsin. The affinity liposomes were prepared by covalently attaching PAB to the surface of small unilamellar liposomes via the hydrophilic spacer arm diglycolic acid. The liposomes were comprised of dimyristoyl phosphatidyl choline, cholesterol, and dimyristoyl phosphatidyl ethanolamine to which the diglycolic acid was attached. The equilibrium binding constant between trypsin and immobilized PAB was shown to be dependent on the PAB density of the liposome surface. Bound trypsin was eluted from the liposomes by the trypsin inhibitor benzamidine. Trypsin was purified from a trypsin/chymotrypsin mixture and from one of its naturally occurring sources, porcine pancreatic extract. A recovery yield from the crude mixture of 68% was obtained with a trypsin purity of 98%. The affinity-modified liposomes were stable in the complex mixture and retained their trypsin binding capacity after multiple adsorption/elution cycles over a 30-day period.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360510
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  • 187
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    Development of computerized feedback control for the continuous phasing of Bacillus subtilis (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 539-545 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360514
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  • 188
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    Transient shear stresses on a suspension cell in turbulence (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 563-571 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model flow field representative of Kolmogorov eddies in turbulence is proposed, and its two parameters are expressed in terms of the known bioreactor variables ε, the rate of turbulent power dissipation, and ν, the fluid kinematic viscosity. The trajectory through this flow field of a small sphere representing a cell is determined, and from that the time-varying local shear rate can be found. This allows calculation of the shear stress at any point on the sphere's surface as it rotates in and moves through the model eddy. The maximum shear stress imposed on the cell by the surrounding turbulence has a range of 0.5-5 dyn/cm2, and can be estimated by 5.33ρ(εν)1/2. The shear stress has two major frequency components with ranges of 1-4 and 20-80 s-1; the higher frequency component is estimated by 0.678(ε/ν)1/2. The rotation of the direction of the shear stress vector at each point on the cell's surface is also discussed. Two ways in which external stresses might affect cell growth are proposed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360603
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  • 189
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    Protein-protein interaction in low water organic media (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 601-607 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Trypsin either modified with polyethylene glycol or as a suspended powder was used to catalyze digestion of protein substrates in benzene in order to get insight into protein-protein interactions in water-immiscible organic media. Depending on whether suspended or soluble trypsin was used, catalysis was found to proceed differently. In the first case, the amount of water in the reaction mixture (up to 1% v/v) appeared to be critical, and adsorption of water from the reaction medium by the protein substrate allowed it to behave as a hydrophilic support material comparable to that involved in immobilized enzymes. In the latter case, the presence of an additional nucleophile was a prerequisite for catalysis to proceed, and thus both water and nucleophile concentrations had some influence on trypsin activity. Phe-NH2 was the most potent nucleophile for proteolysis catalyzed by polyethylene glycol-modified trypsin in organic media containing 1-2% water (v/v). The organic solvent-soluble enzyme was found to bind reversibly to the protein substrate as a function of both extent of hydration of the reaction medium and time of incubation. The overall results strongly suggested that modified trypsin catalyzed peptide bond hydrolysis at the protein substrate-organic solvent interface. Peptide mapping of bovine insulin digest by reversed-phase high-performance liquid chromatography definitely showed that enzyme-catalyzed proteolysis did occur in organic solvents with a concomitant and significant transpeptidation reaction.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360607
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  • 190
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    Continuous production of prourokinase in feed harvest and perfusion cultures (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 623-629 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The production of prourokinase (PUK) by a human kidney tumor cell line is studied in long term cultures. Cells are grown on microcarriers which are retained inside the reactor by sedimentation or with a spin filter. Two modes of operation are compared: feed harvest at an average medium exchange rate of 0.3 d-1 and continuous perfusion at a higher dilution rate of 1.5 d-1. In the two systems a stable production of PUK has been maintained for more than 400 h. Kinetics of cellular growth, nutrient consumption, and metabolite and PUK excretion are similar. After an initial rapid growth period, one observes a 10-fold reduction in all the cellular metabolic activities during the stationary phase. Continuous perfusion yields a higher cell density (7 × 106 cells·mL-1) than feed harvest (3 × 106 cells·mL-1), which results in a twofold increase in the reactor productivity. But higher final enzyme activities, about 250 ru·mL-1, are obtained in the feed harvest recovered medium than in the perfusion medium, 100-150 ru·mL-1. The cumulative medium consumption per mass of product is the same in the repeated batch and in the continuous operation mode.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360610
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  • 191
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    On-Line fermentation monitoring using flow injection analysis (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 647-651 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360614
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  • 192
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    Effect of metal ion concentration on a biological reactor (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 685-693 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Saccharomyces cerevisiae (yeast) cells were employed as a source of alcohol dehydrogenase in the NAD+-to-NADH reaction. The cells were immobilized in calcium alginate monofilament fibers and used in a biological reactor. The alginate could not be heat sterilized since temperatures above 80 °C caused the polymer chains to degrade. The same proved true for the high pH necessary for the reaction, but the alginate strength was increased by Ba2+ solution treatment. X-ray probe analysis showed that about 30% of the Ca2+ sites exchanged with the Ba2+ ions. The Ba2+ ions (as well as the Ca2+ ions) permeabilized the cells and increased the reaction rate. Long term trials showed that Ba2+ ions were slowly elutriated from the fiber biocatalyst, causing a drop in reaction rate. The trend certainly was reversible as far as the fiber was concerned. It is assumed that the permeabilization of the cells by the Ba2+ ions was a reversible process.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360706
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  • 193
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    Complications encountered using cibacron blue F3G-A as a ligand for affinity precipitation of lactate dehydrogenase (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 737-743 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The use of the affinity interaction between Cibacron Blue F3G-A (CB) and NADH-dependent enzymes to selectively precipitate these enzymes has been examined. An attempt was made to form crosslinked precipitates of lactate dehydrogenase (LDH) using bis- and poly-CB conjugates. When precipitation was not observed, an examination of the interaction between the enzyme and the conjugated CB was made. Quasielastic light scattering indicated only a slight radius increase, the greatest being from 50 to 130 Å, when a CB-dextran conjugate was added to a solution of LDH, and no increase when bis-CB made with a 1, 6-diaminohexane spacer was added to a similar solution. The results of enzyme inhibition studies showed that conjugated CB bound at the NAD+ site of LDH. Spectral measurements of the conjugated CB below 5 μM were similar to those reported for a stacking interaction that occurs in solutions with CB concentrations above 5 μM We conclude that the conjugated CB is binding to the LDH, but that a competing dye stacking interaction prevents extensive cross-linking of the LDH, and thus inhibits precipitation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360712
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  • 194
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    Relationship between oxygen consumption rate and cellular activity of mammalian cells cultured in serum-free media (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 759-762 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360715
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  • 195
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    Deactivation of catalase by hydrogen peroxide (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 783-789 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: When a mechanism is used to determine possible deactivation kinetics, a certain consistency with the kinetics of the main reaction is found. This result is examined in the light of experimental evidence obtained with bovine liver and Aspergillus catalases.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360805
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  • 196
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    Parametric analysis of the errors associated with the Michaelis-Menten equation (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 1141-1150 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Based on the well-known mechanism describing Michaelis-Menten kinetics, three rate expressions may be developed: the exact solution (Model 1), a rate equation resulting from the pseudo-steady-state assumption (Model 2), and Model 2 with the additional assumption that the amount of free substrate is approximately equal to the total amount of substrate (Model 3). Although Model 1 is the most precise, it must be integrated numerically and it requires three experimentally determined parameters. Models 2 and 3, however, are simpler and require only two parameters. Using dimensionless forms of the three models, we have evaluated the errors in the two simplified models relative to the exact solution using a wide range of parameter values. The choice of model for reactor design depends on the initial substrate to enzyme ratio (α0), and on the ratio of the Michaelis-Menten constant to the enzyme concentration (σ). Based on a 2% model error criteria, when α0 〉 15 or σ ≥ 100, Model 3 is adequate; if 5 〈 α0 〈 15, or if σ ≥ 10, then Model 2 may be used; and if α0 〈 5 and σ 〈 10, then the exact solution (Model 1) is required.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260361109
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  • 197
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    Analysis of cloned SUC2 gene expression in continuous culture of recombinant Saccharomyces cerevisiae (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 960-964 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260360911
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  • 198
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    Foam fractionation of globular proteinsPaper No. 12368, Agricultural Experimental, Station, Purdue University, West Lafayette, Indiana. (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 947-959 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Foam fractionation of bovine serum albumin (BSA) was studied as a model system for potato wastewater. The effects of feed concentration, superficial gas velocity, feed flow rate, bubble size, pH, and ionic strength on the enrichment and recovery of BSA were investigated in a single-stage continuous foam fractionation column. Enrichments ranged from 1.5 to 6.0 and recoveries from 5 to 85%. The feed concentrations were varied from 0.01 to 0.2 wt %, and enrichments were found to increase with lower feed concentrations. Enrichments also increased with lower superficial gas velocities and larger bubble sizes. At sufficiently low feed flow rates, enrichment was found to increase with an increase in the flow rate, eventually becoming insensitive to the feed flow rate at higher values. The pH was varied from 3.5 to 7.0 and ionic strength from 0.001M to 0.2M. The effects of pH and ionic strength were found to be coupled with bubble size. A minimum bubble size was found at pH 4.8, the isoelectric point of BSA, resulting in a minimum in the enrichment. Bubble size, and thus enrichment, was found to increase as the ionic strength decreased from 0.2M to 0.01M. Previous models1,2 for the hydrodynamics of foam column were extended for a singlestage continuous foam fractionation column for the prediction of enrichment and recovery. The model assumed adsorption equilibrium, infinite surface viscosity, and bubbles of the same size. Though coalescence was formally accounted for in the model by considering bubble size as a function of foam height, calculations for the experimental runs were performed only for the case of no coalescence. Quantitative predictions of enrichment and recovery could not be made with a single representative bubble size because of the broad inlet bubble size distribution as well as broadening of the distribution as a result of coalescence. The experimental enrichments were higher and recoveries were lower than the model predictions, the discrepancy being more pronounced at lower feed concentrations because of increased coalescence. The higher enrichments are due to the predominant effect of internal reflux as a result of coalescence whereas the lower recoveries are a result of detrimental effects of broadening bubble size distributions.
    Additional Material: 17 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260360910
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  • 199
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    A process for the production of human proinsulin in Saccharomyces cerevisiae (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 339-348 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to develop a large-scale fermentation process for the production of human proinsulin in yeast, the intra-cellular expression of a human superoxide dismutase-human proinsulin fusion product (SOD-PI) has been studied. The expression of SOD-PI in Saccharomyces cerevisiae is regulated by a hybrid alcohol dehydrogenase 2/glyceraldehyde-3-phosphate dehydrogenase promoter. The promoter is repressed by glucose and derepressed by depletion of glucose. Although the genetic stability of the construction is shown to be poor under product-inducing conditions, it is demonstrated in shake flask experiments that a stable expression potential can be maintained in a complex medium for more than 60 generations by maintaining excess glucose throughout the cultivations. These results have been confirmed in continuous cultures in chemostat and turbidostat experiments. Addition of the glucose analogs glucosamine, 2-desoxyglucose, methylglucose, and thioglucose also leads to repression of SOD-PI formation. The analogs, however, are not suitable for improving genetic stability during propagation because of growth inhibition. In batch fermentation experiments in a complex medium at 30°C, it has been demonstrated that initial glucose concentrations up to 50 g/L result in high specific SOD-PI yields giving an overall yield of up to 700 mg SOD-PI/L whereas higher glucose concentrations lead to both lower specific and overall yields due to depletion of critical medium components in the production period. In fed-batch experiments at 30°C it has been possible to obtain high specific SOD-PI yields even at high biomass concentrations by feeding glucose at a constant rate of 1.5 g/L/h for 40 h followed by a feeding of ethanol at 1.0 g/L/h for 24 h, thus giving an overall yield of 1200 mg/L. Decreasing the temperature from 30 to 26°C leads to improved yields in batch as well as fed-batch experiments. The optimized fed-batch fermentation process which is suitable to be scaled up to the cubic meter level has been tested in 200-L fermentations resulting in yields of more than 1500 mg/L of the fusion protein which conveniently can be used as a precursor in the production of recombinant human proinsulin.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350403
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  • 200
    Electronic Resource
    Electronic Resource
    Masthead (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350501
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