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  • 1980-1984  (3,088)
  • Biochemistry and Biotechnology  (1,710)
  • Engineering General  (1,377)
  • Nuclear reactions
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 66-73 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of growth rate on Escherichia coli plasmid content and expression of a cloned-gene product has been described by a mathematical model based upon the molecular mechanism of λdv plasmid replication and known relationships between growth rate and transcription and translation activities of the host cell. The model simulates correctly decreases in plasmid content with increasing growth rate as observed experimentally for pBR322, NR1, R1, and Col E1 plasmids. A maximum with respect to growth rate in intracellular product accumulation is indicated by the model, as is a transient overshoot in product concentration following a shift from smaller to larger growth rate. Available data, although very limited, show the same trends. These results, obtained without parameter or kinetic form adjustments or manipulation, clearly illustrate the advantages of kinetic descriptions of recombinant systems based upon the pertinent molecular mechanisms.
    Additional Material: 4 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 92-99 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The leaching of pyrite sulfur from coal employing Thiobacillus Ferrooxidans was studied in a continuous stirred tank reactor at a variety of dilution rates (0.02-0.11 h-1) and coal surface areas (0.25-1.0 m2/mL). The bacterial leaching rate was found to increase with increasing coal surface area concentration and increasing dilution rate. The bacterial concentration on the coal surface was related to the bacterial concentration in solution by a irreversible second-order (of the second kind) kinetic equation. The concentration of bacteria on the coal in all experiments was the concentration at saturation. Step changes in the coal concentration were observed to result in dramatic declines in bacterial concentration in solution. A bacterial mass balance model was employed to calculate the specific growth rate on the solid which was observed to increase with increasing dilution rate.
    Additional Material: 8 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 121-127 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A kinetic model was devised for the hydrolysis and synthesis of maltose and isomaltose by two glucoamylases from Rhizopus niveus and Aspergillus niger, and the validity of the model was verified experimentally at 313 K and pH 5.0. For both enzymes, the formations of maltose and isomaltose from glucose were parallel reversible reactions, and glucosyl transfer between maltose and isomaltose was not observed. The enzymes catalyzed rapid hydrolysis and synthesis of maltose. Isomaltose was hydrolyzed and synthesized more slowly, but the level produced from glucose was much higher than that of maltose. These hydrolysis and condensation reactions were expressed well by the model.
    Additional Material: 11 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 142-147 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biomass autoflocculation in outdoor algal cultures was found to be associated with increases of culture pH levels, due to CO2 consumption by the algal photosynthetic activity. Under these alkaline conditions, some medium chemical ions precipitated together with the algal biomass. The chemical substances involved with the process and its dependence on pH value were studied by simulation of autoflocculation in laboratory experiments. Proper concentrations of calcium and orthophosphate ions in the medium are important for autoflocculation and, in order to attain it within the pH range 8.5-9.0, the culture should contain 0.1mM-0.2mM orthophosphate and 1.5mM-2.5mM calcium prior to raising the pH level. Calcium phosphate precipitates are considered as the flocculating agent which reacts with the negatively charged surface of the algae and promotes aggregation and flocculation.
    Additional Material: 7 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 188-190 
    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 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 374-376 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 389-389 
    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
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 386-388 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 397-402 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 403-405 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 468-476 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The dynamic analysis of a continuous, aerobic, fixed-film bioreactor has been performed. Rigorous mathematical models have been developed for a fluidized-bed fermentor with biofilm growth. The transient performance of the reactor is appraised in terms of outlet penicillin concentration for constant, as well as variable carbon substrate feed rates. The effect of the reactor oxygen transfer capacity is elucidated for those cases employing substrate feeding strategies. The results show that penicillin production in a continuous, fixed-film bioreactor reaches a maximum with processing time, but subsequently decreases as cell mass accumulates and substrate deficiencies occur. The maximum production level can be maintained for increased operating times if the substrate supply is continuously increased. The duration of this prolonged production is a direct function of the rate of increase and the operating time at which the increase is initiated. The oxygen transfer capacity of the reactor was found to be important to the effectiveness of a feeding strategy.
    Additional Material: 7 Ill.
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 488-496 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Some studies on the adsorption of cellulase on cellulose revealed part of the mechanisms involved in the enzymatic hydrolysis of cellulose and provided some clues to the synergistic mechanism of cellulase complex. The adsorption of cellulase was significantly affected by the reaction conditions and physical chemical characteristics of cellulose. Endoglucanase consisted of adsorbable and nonadsorbable components. Cellobiohydrolase had the strongest adsorption affinity. Each cellulase component is postulated to have distinctly different adsorption sites on cellulose, corresponding to the active sites in the hydrolysis reaction. Competitive adsorption kinetics between cellulase components were also observed during the adsorption process. The degree of competitive adsorption was most remarkable when the composition of cellulase components was nearly the same as that in the crude cellulase complex. This seems to show the optimal relative composition of cellulase components. The synergism between cellobiohydrolase and endoglucananse could be elucidated more clearly by this competitive adsorption model of the reaction mechanism.
    Additional Material: 15 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 503-507 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two strains of human foreskin fibroblast cells were incapable of sustained growth in a matrix perfusion culture system, possibly because of their inability to attach to the fiber surfaces. Addition of microcarrier beads to the extracapillary space allowed attaining high cell densities in excess of 107 cells per culture unit. Microcarrier beads were tested in hollow fiber culture devices containing membranes of 104 or 105 D nominal porosities. Best results were obtained when initial cell densities of at least (2-3) × 106 cells were used in units with 105 D pore size membranes and DEAE-Sephadex or polyacryl-amide microcarrier beads in the extracapillary space. This extension of the matrix perfusion system should be useful for growing other anchorage dependent cells while retaining the advantages of perfusion culture.
    Additional Material: 5 Ill.
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 518-527 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Acid phosphatase (E.C.3.1.3.2.) thermal deactivation at pH 3.77 has been investigated by monitoring the enzyme activity as a function of time in the hydrolysis of p-nitrophenyl phosphate. The experimental curves obtained show a two-slope behavior in a log (activity)versus-time plot, which indicates that deactivation occurs via a complex mechanism. From the dependence of the kinetic parameters on both deactivation and hydrolysis temperatures, it is inferred that the deactivation mechanism involves intermediate, temperature-dependent, less-active forms of the enzyme. This interpretation is confirmed by the results of additional tests in which the temperature was suddenly changed during the deactivation process.
    Additional Material: 13 Ill.
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 528-536 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Plasmid gene product accumulation in a cell population depends on the fraction of plasmid-containing cells and the distribution of single-cell plasmid content. These important population properties have been related to plasmid replication regulation and kinetics and to plasmid segregation rules at the single-cell level using population balance mathematical models. Budding yeast populations are considered in detail because of the practical potential of yeast host-vector systems and because of the model complications introduced by the asymmetric division pattern observed for Saccharomyces cerevisiae at all but the largest growth rates. Solutions are presented for several different reasonable models of plasmid replication and segregation. The results offer potential for identification of important qualitative features of yeast plasmid replication and of model parameter values from average and segregated experimental data on yeast populations.
    Additional Material: 8 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 557-559 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 560-563 
    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.
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 265-268 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biomass, mainly consisting of an acidic polysaccharide produced by Zoogloea ramigera, has been used as an adsorbing agent in a continuous process for the recovery of metal. The adsorption of copper has been studied with respect to retention time, biomass concentration, and reaction pH, in order to determine the optimal conditions for copper recovery. The results indicate that the uptake of copper is rapid and efficient. About 0.17 g Cu is adsorbed per gram of biomass within 10 min. At high biomass concentrations, the total amount of copper removed from solution is high, but the specific amount of copper adsorbed to biomass is low. The biomass exhibits a higher adsorptive uptake at low concentrations.
    Additional Material: 3 Ill.
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984) 
    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
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 308-314 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The cultural conditions for the production of enhanced formation of L-serine (up to 7 g/L) are described with the methylotrophic bacterium Pseudomonas 3 ab (DSM 672). The batch process is divided into three parts: (1) the biomass production phase, (2) substrate limitation period, and (3) L-serine accumulation phase. The initial specific production rate of qp = 0.1 g L-serine/g dry wt/h is based on the inhibition of the L-serine pathway. This is accomplished by high precursor concentrations (glycine) and a pH shift to pH 8.5. The enzymatic background is discussed. Furthermore, a coupling of the L-serine process with a L-tryptophan-producing process is demonstrated.
    Additional Material: 5 Ill.
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  • 21
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 328-334 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Optimal automatic bioreactor control requires a mathematical model adapted to the potency of reliable sensors. A new relationship describing the kinetic behavior of alcoholic fermentation is discussed. By analogy with chemical kinetics, the biological rate of substrate consumption is related to substrate and product concentration by the following equation: \documentclass{article}\pagestyle{empty}\begin{document}$$r_s = kS^\alpha P^\beta$$\end{document} Using the well known yield relation between product and substrate, it is possible to describe in both batch and continuous cultures the ethanol and sugar concentrations versus time. This pattern has been successfully tested on several fermentations performed by yeasts (S. cerevisiae, S. bayanus, and S. cerevisiae sake) and a bacterium (Z. mobilis). This simple relationship is proposed as a tool for process control alcoholic fermentation.
    Additional Material: 11 Ill.
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  • 22
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 340-346 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The rate of celluose degradation, limited due to the inhibition by cellobiose, can be increased by the hydrolysis of cellobiose to glucose using immobilized β-glucosidase. Production of β-glucosidase in four yeasts was studied and a maximum activity of 1.22 IU/mg cells was obtained in cells of Pichia etchellsii when grown on 3% cellobiose as the sole carbon source. A study of the immobilization of β-glucosidase containing cells of Pichia etchellsii on various solid supports was conducted and immobilization by entrapment in calcium alginate gel beads was found to be the most simple and efficient method. A retention of 96.5% of initial activity after ten sequential batch uses of the immobilized preparation was observed. The pH and temperature optima for free and immobilized cells were the same, i.e., 6.5 (0.05M Maleate buffer) and 50°C, respectively. Even though the temperature optimum was found to be 50°C, the enzyme exhibits a better thermal stability at 45°C. Beads stored at 4°C for six months retain 80% of their activity. Kinetic studies performed on free and immobilized cells shown that glucose is a noncompetitive product inhibitor.The immobilized preparation was found to be limited by pore diffusion but exhibited no film-diffusion resistance during packed bed column indicated by a low dispersion number of 0.1348. A model for reaction with pore diffusion for a noncompetitive type of inhibited system was developed and applied to the cellobiose hydrolysis system. The rate of reaction with diffusional limitations was determined by using the model and effectiveness factors were calculated for different particle sizes. An effectiveness factor of 0.49 was obtained for a particle diameter of 2.5 mm. The modified rate expression using the effectiveness factor represented batch and packed bed reactor operation satisfactorily. The productivity in the packed bed column was found to fall rapidly with increase in conversion rate indicating that the operating conditions of the column would have to be a compromise between high conversion rates and reasonable productivity. A half-life of over seven days was obtained at the operating temperature of 45°C in continuous operation of the packed bed reactor. However, the half-life in the column was found to be greatly affected by temperature, increasing to over seventeen days at a temperature of 40°C and decreasing to less than two days at 50°C.
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  • 23
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 392-393 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 24
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 25
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 407-411 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Purification of partially purified fibrinolytic enzyme was attempted by chromatography on DEAE-cellulose (D-52) column. The results indicated the resolution of three protein components and one minor component. It was shown that the first component was the major of the applied sample. Examination of fibrinolytic activity of the different fractions of components one and two indicated that only the first component possessed fibrinolytic activity. Fibrinolytic activity of the applied sample was completely recovered by the first enzyme component, and the most active fraction of this enzyme component showed 3.3-fold purification. The pure fibrinolytic enzyme was relatively more stable at pH 6.98, which was also optimal for its activity. After heating the enzyme solution (pH = 6.98) at 55 and 60°C for 15 min, the enzyme still retained 34.7 and 17.3% of its original activity, respectively. Zinc ions partially inhibited the enzyme. Copper ions activated the enzyme. Iodine partially inhibited the fungal fibrinolytic enzyme at a final concentration of 10-4M; at 10-2M complete inactivation was brought about. The p-chloromercuribenzoate at a final concentration of 10-2M brought about partial inhibition whereby the enzyme lost about 33% of its original activity. Reduced glutathione brought about activation of the enzyme, while trypsin inhibitor did not show any effect on enzyme activity.
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  • 26
    Electronic Resource
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 457-467 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The analysis of a continuous, aerobic, fixed-film bioreactor is performed by simulating the behavior of penicillin production in a three-phase fluidized bed. Rigorous mathematical models are developed for a fluidized-bed fermentor in which bioparticles are fluidized by the liquid medium and air. The steady-state performance of the fluidized-bed reactor is appraised in terms of penicillin productivity and outlet concentration by considering the two extremes in contacting patterns, complete back-mix and plug flow, in the absence of a growing biofilm. The results show that the complete back-mix contacting pattern is preferred over that of plug flow due to the nature of the penicillin kinetic relationships. It is also shown that for the dual-nutrient (glucose and oxygen) penicillin reaction system the optimum biofilm thickness does not equal the penetration depth of a limiting nutrient, but depends upon the total reactor configuration.
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  • 27
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 513-517 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Adsorption of water and ethanol on four starches has been studied in the temperature range of 50-90°C. The results show that adsorption of water on starch-based materials is enhanced when the amount of amylopectin is highest. Adsorption of ethanol is not significantly affected by the kind of starch used. Heats of adsorption calculated from retention data are in the range from -9.3 to -13.7 kcal/g mol for water and -5.6 to -6.76 kcal/g mol for ethanol. Calculated free energies of adsorption suggest that adsorption is most spontaneous at lower temperatures as expected.
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  • 28
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 877-884 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A computer model is described which models an asynchronous population of E. coli by using a large, but finite number of representative single cells. Asynchrony generation and maintenance occurs at the single cell level by modulating the activity of an enzyme responsible for septum formation. Such modulation introduces cycle time imprecision and does not require the introduction of any new parameters into the single-cell model. Based on comparisons to experiment, reasonable predictions are possible for changes of cellular dry weight during exponential growth and turbidostat washout, and overall chemostat cell yields and changes in cell number, glucose concentration, and cell size distribution for a chemostat subject to a step change in dilution rate. Additionally, a correlation between cell RNA content and size is predicted as is an inertial effect when chemostat residence time is decreased under conditions of initially high glucose concentrations. Limitations imposed by the model's finite nature and their solutions are discussed.
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  • 29
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 901-904 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Immobilized β-galactosidase was obtained by crosslinking the enzyme with hen egg white using 2% glutaraldehyde. The gel obtained could be lyophilized to give a dry enzyme powder. The pH optimum of both the soluble and immobilized enzyme was found to be 6.8. The immobilized enzyme showed a higher Km for the substrates. The extent of enzyme inhibition by galactose was reduced upon immobilization. The stability towards inactivation by heat, urea, gamma irradiation, and protease treatment were enhanced. The bound enzyme as tested in a batch reactor could be used repeatedly for the hydrolysis of milk lactose. The possible application of this system for small-scale domestic use has been suggested.
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  • 30
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 926-935 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Methods are presented for examining the consistency of experimental data for microbial growth where light energy is converted to chemical energy through photosynthesis. True growth yield and maintenance parameters are estimated for several sets of available experimental data. Methods of parameter estimation are presented which allow all of the measured variables to be used simultaneously for parameter estimation. The results show that a wide range of values have been found for the true growth yield and maintenance parameters. Values of the true growth yield range from 0.04 to values above those predicted by the Z-scheme model for photosynthesis.
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  • 31
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 942-947 
    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 operational strategy is shown to offer a viable means of enhancing plasmid stability in chemostat systems where plasmid loss is a common problem. Feedback control can be used to stabilize coexistence states, which are naturally unstable in the system investigated, and thus gurantee retention of the plasmid-carrying strain. The strategy exploits the normally undesirable characteristics of substrate inhibited growth kinetics, and is illustrated with specific reference to methanolutilizing organisms. Since the methodology may be easily implemented in practice, it offers an alternative to costly environmental methods such as antibiotic addition.
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  • 32
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    Biotechnology and Bioengineering 26 (1984), S. 973-981 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 12 Ill.
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  • 33
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    Biotechnology and Bioengineering 26 (1984), S. 613-619 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Batch growth tests were performed under both replicating and nonproliferating (no nitrogen source in medium) conditions with acclimated heterogenous populations that utilized phenol as a sole source of carbon and energy. It was shown that the acclimated populations could efficiently remove the toxic waste component phenol under nonproliferating conditions by utilizing an oxidative assimilation mechanism. The phenol was assimilated and converted into nonnitrogenous storage products. During the assimilation process, the cells had a tendency to excrete some product (nonsubstrate) chemical oxygen demand (COD). Bench-scale oxidative assimilation units were operated by sequentially feeding a carbon source (phenol) and nitrogen source (ammonium sulfate) to heterogeneous populations. This demonstrated that, subsequent to the addition of the nitrogen source to the medium, the cells utilized the stored carbon for replication. Four of these units were operated at different phenol COD-to-ammonia-nitrogen ratios of 10:1, 20:1, 40:1, and 50:1. All of these units demonstrated excellent removal of phenol using an oxidative assimilation mechanism. These results suggested the feasibility of utilizing a continuous flow oxidative assimilation process for the treatment of nitrogen-deficient phenolic wastes. This process would be advantageous over conventional treatment processes in that it would realize a savings in chemical costs (ammonia as nitrogen source) and prevent leakage of excess ammonia from the system.
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  • 34
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    Biotechnology and Bioengineering 26 (1984), S. 1038-1041 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The conversion of ethanol to ethyl acetate has an advantage as a method of ethanol recovery since ethyl acetate is amenable to simple solvent extraction. The potential of Candida utilis in this conversion was studied. The kinetics of accumulation of ethanol and ethyl acetate in glucose-grown C. utilis showed that ester formation resulted from ethanol utilization under appropriate aeration and was inhibited by Fe3+ supplementation. Candida utilis converted ethanol to ethyl acetate optimally at pH 5.0-7.0. The five-hour rate of ester production increased as the ethanol concentration increased to 10 g/L, and rapidly declined to zero at concentrations exceeding 35 g/L. Thus, C. utilis has potential to recover dilute ethanol in the form of ethyl acetate.
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  • 35
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    Biotechnology and Bioengineering 26 (1984), S. 658-664 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The covalent coupling of an invertase from baker's yeast onto an agricultural by-product, corn grits, has been developed. The optimal conditions for each step of the chemical modification of the support have been determined: oxidation with sodium metaperiodate, amination with ethylenediamine, reduction with sodium cyanoborohydride, and activation with glutaraldehyde. Activities up to 7.2 × 104 μmol reducing sugars produced/min g support could thus be achieved. Invertase coupling onto corn grits yields a derivative with a 25 times higher activity than when coupling this enzyme onto porous silica. The operational stability of invertase immobilized onto corn stover was found to be very high, with a half-life of up to 365 days at 40°C when using a 2M sucrose solution as substrate. This immobilization method could be easily scaled up to the preparation of 10 kg of invertase derivative.
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  • 36
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    Biotechnology and Bioengineering 26 (1984), S. 654-657 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Continuous cooker prototypes of very simple design, using electricity as a primary energy source, were developed for the process of cooking and liquefaction of starch suspensions. Previous work on equipment using microwave dielectric heating has already been reported. Results of energy consumption as low as 330 kcal/kg based on starch content were achieved. Considering these results and looking for new solutions or engineering concepts, the authors have been investigating the possibility of using electric energy at 60 Hz for direct resistive heating, in which the starch suspension is the proper “resistor.”The most important results of energetic yield obtained until now, working in a continuous process of cooking-liquefaction, are not larger than 235 kcal (272 Wh)/kg based on starch content. These results were obtained using a commercial grade α-amylase from B. subtillis, working with temperatures ranging from 70 to 75°C, and with residence times in the reactor not greater than 1.5 min. The experiments of saccharification and fermentation accomplished as a test for the efficiency of this heating technique gave good results (as with a conventional technique) and thus enabled us to proceed with the studies.
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  • 37
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    Biotechnology and Bioengineering 26 (1984), S. 687-690 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The refractory organic sulfur compound dibenzothiophene (DBT) has been oxidized by the thermophilic, sulfur oxidizing organism Sulfolobus acidocaldarius. Sulfate ions were released into the medium as the oxidation product. The kinetics of this oxidation have been investigated on the basis of sulfate released as a result of oxidation. Dibenzothiophene was found to be inhibitory to the organisms for initial concentrations over 500 mg/L. The organism may prove to be capable of oxidizing thiophene compounds present in oil refinery wastewater, coal, and crude oil.
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  • 38
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    Biotechnology and Bioengineering 26 (1984), S. 727-736 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Nonuniform enzyme distributions can be obtained by kinetic control of the immobilization process. Such heterogeneous biocatalysts exhibit higher effectiveness compared to conventional immobilization procedures, when the mass transfer of substrates or products is limiting. Model calculations provide some insight into the relative weight of the immobilization parameters with respect to optimal control of the enzyme distribution. Experimental results and model calculations show that considerably improved effectiveness of biocatalysts can be obtained. The role of external mass transfer is emphasized.
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  • 39
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    Biotechnology and Bioengineering 26 (1984), S. 737-741 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A catalase has been purified from aerobically grown Escherichia coli K12. The enzyme exhibits unorthodox properties compared with catalyse from bovine liver and seems to be identical to hydroperoxidase II from E. coli. A mathematical model is presented which makes it possible to calculate the steady-state concentration of hydrogen peroxide in an open system. The model has been verified experimentally. It has been shown that the catalase from E. coli is better suited than the bovine liver enzyme for oxygen supply to cell suspensions using hydrogen peroxide.
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  • 40
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    Biotechnology and Bioengineering 26 (1984), S. 1167-1175 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The rheological behavior of cultures of Cellulomonas uda with shredded printed newspaper as the carbon source was studied. The initial substrate concentrations ranged from 23 to 60 g/L. The changes in apparent viscosity were followed on-line by applying a commercially available process viscometer and discretely using a rotational viscometer with an anchor impeller. During the time of highest cellulose degradation, the broths exhibited a pseudoplastic behavior which could be explained satisfactorily by the power-law model. At the end of cultivation when cellulose degradation slowed down, the broths became Newtonian in behavior. Endo-1,4-β-glucanase, 1,4-β-xylanase, β-glucosidase, and β-xylosidase activities were also determined during cultivation as well as cellulose degradation and cell mass production. The beginning of endoglucanase formation and the start of the final viscosity decrease of the bacterial paper pulp suspensions could be correlated.
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  • 41
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    Biotechnology and Bioengineering 26 (1984), S. 1146-1154 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: α-Chymotrypsin was immobilized with a high coupling yield (up to 80%) to tresyl chloride activated Sepharose CL-4B.The immobilized enzyme was tested for its ability to synthesize soluble peptides from N-acetylated amino acid esters as acyl donors and amino acid amides as acceptor amines in water-water-miscible organic solvent mixtures. It was found that the yield of peptide increased with increasing concentration of organic cosolvent. Almost complete synthesis (97%) of Ac-Phe-Ala-NH2 was obtained from Ac-Phe-OMe using a sixfold excess of Ala-NH2. The rate of peptide formation in aqueous-organic solvent mixtures was good. Thus, 0.1M peptide was formed in less than 2 h in 50 vol% DMF with 0.1 mg immobilized chymotrypsin/mL reaction mixture. The immobilized enzyme distinguished between the L and D configurations of acceptor amino acid amides even in high concentration of nonaqueous component (90% 1,4-butanediol). The effect of temperature was studied. It was found that both the yield of peptide and the stability of immobilized enzyme increased when the temperature was lowered. Experiments could be performed at subzero temperatures in the aqueous-organic solvent mixtures resulting in very high yield of peptide. After three weeks continuous operation at 4°C in 50% DMF, the immobilized enzyme retained 66%of its original synthetic activity. The activity of the immobilized enzyme was better conserved with a preparation made from agarose with a higher tresyl group content compared to a preparation made from a lower activated agarose, indicating that multiple point of attachment has a favorable effect on the stability of the enzyme in aqueous-organic solvent mixtures. The major advantage of using water-miscible instead of water-immiscible organic solvents to promote peptide syntheses appears to be the increased solubility of substrates and products, making continuous operation possible.
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  • 42
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    Biotechnology and Bioengineering 26 (1984), S. 1209-1218 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Relationships between the total rate of biomass growth and the rate of ammonia addition to a fermentor for pH control are presented. These equations make use of the concept of reaction invariants and provide the additional information needed for bioreactor identification. They are especially useful when the RQ measurement is not sufficient for this purpose, such as when sensitivities arise with the measured values of the respiratory quotient or when fermentation products are formed. The cases of batch, fed-batch and continuous fermentations, forming products with or without acidic/basic properties are considered. The derived relationships were successfully tested with nonbiological acid-base continuous flow reaction systems and subsequently applied to the identification of the continuous yeast fermentation of glucose to ethanol. Results of these experimental studies are also presented.
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  • 43
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    Biotechnology and Bioengineering 26 (1984), S. 820-823 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 44
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    Biotechnology and Bioengineering 26 (1984), S. 827-827 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 45
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    Biotechnology and Bioengineering 26 (1984), S. 828-835 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Upjohn Company uses filtration to remove microorganisms and particulates from air and other gases which may come in contact with sterile products. To validate the microbial retentivity of these filters, they were challenged with an aerosol of Bacillus subtilis var niger spores. An aerosol challenge was used because it more closely simulated the use for which these filters were designed. The test apparatus was constructed of autoclavable components using a jet-type nebulizer and heated air mixing tube. Characterization of the aerosol particle size distribution with a particle size analyzer demonstrated that 80% of the particles had a diameter of × 3.0 times;m and that the particles had a mean mass diameter of 1.9 times;m with a geometric standard deviation of 1.8 times;m. Studies conducted with aerosols of Bacillus subtilis var niger spores demonstrated that the test apparatus could recover ca. 50% of the spores that were aerosolized. Hydrophobic filters from various manufactures were challenged with an aerosol of at least 108 spores of Bacillus subtilis. All filters tested could retain at least 109 spores when physical integrity of the filter was verfield.
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  • 46
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    Biotechnology and Bioengineering 26 (1984), S. 871-876 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In many cases of fermentation processes, it is difficult to measure all of the state variables needed to indicate the culture state and to predict state changes. We propose the use of time-series data of measurable state variables instead of unmeasurable to describe the fermenatation process. We also employ a discrimination method of independent variables of regression analysis using statistical measures, PSS and AIC. These statistical procedure were applied to fed batch culture for yeast production under aerobic conditions, and the effectiveness was ascertained experimentally.
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  • 47
    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 pretreatment process variables [straw concentration between 20 and 90 kg volatile solids (VS)/m3, temperature between 30 and 85°C, and alkaline dosage between 0 and 80 g NaOH/kg VS] on acidogenesis and methanogenesis were investigated. Rates of acidogenesis and methanogenesis were determined using firstorder kinetics, and ultimate acid and methane yields were measured. The acid yield was not affected by pretreatment concentration or temperature, but increased as alkaline dosage increased. The acidogenesis rate was not affected by pretreatment temperature or alkaline dosage, but decreased as the substrate concentration increased. This decrease in the acidogenesis rate was attributed to a decrease in the inoculum: substrate ratio as the substrate concentration increased. The methane yield and methanogenesis rate were not affected by pretreatment substrate concentration or temperature, and both increased with alkaline dosage up to about 40 g NaOH/kg VS, then remained relatively constant above 40 g NaOH/kg VS.
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  • 48
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    Biotechnology and Bioengineering 26 (1984), S. 959-969 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A series-type enzyme deactivation model is utilized to theoretically analyze and to quantify the effect of chemical modifier concentration on the eventual level of enzyme activity stabilization, α2. An increase in the concentration of phosphate ion and NADP increases α2 for the enzymes studied. One example of each enzyme deactivation is given wherein the introduction of chemical modifiers changes the deactivation mechanism from a single-step to a series-type mechanism, and from a series-type to a single-step mechanism. Simple empirical equations are proposed to quantify the effect of chemical modifier concentration on α2.
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  • 49
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    Biotechnology and Bioengineering 26 (1984), S. 988-991 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It has been demonstrated that the dilution of samples prior to the carboxymethylcellulase and xylanase assays causes serious discrepancies in the numerical values obtained for the enzyme activities. Even when the sample is assayed with the identical procedure, one could obtain different numerical values of the enzyme activity U depending on how much this sample has been diluted before the enzyme assay. Two crude commercial cellulase samples of Aspergillus niger and Trichoderma viride as well as the culture filtrate of our newly isolated acidophilic fungus have been used for the demonstration. An empirical method for reporting the cellulolytic activity by taking into account this dilution effect is proposed.
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  • 50
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Growing cells of Saccharomyces cerevisiae immobilized in calcium alginate gel beads were employed in fluidizedbed reactors for continuous ethanol fermentation from cane molasses and other sugar sources. Some improvements were made in order to avoid microbial contamination and keep cell viability for stable long run operations. Notably, entrapment of sterol and unsaturated fatty acid into immobilized gel beads enhanced ethanol productivity more than 50 g ethanol/L gel h and prolonged life stability for more than one-half year. Cell concentration in the carrier was estimated over 250 g dry cell/L gel. A pilot plant with a total column volume of 4 kL was constructed and has been operated since 1982. As a result, it was confirmed that 8-10%(v/v)ethanol-containing broth was continuously produced from nonsterilized diluted cane molasses for over one-half year. The productivity of ethanol was calculated as 0.6 kL ethanol/kL reactor volume day with a 95% conversion yield versus the maximum theoretical yield for the case of 8.5% (v/v) ethanol broth.
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  • 51
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    Biotechnology and Bioengineering 26 (1984), S. 1032-1037 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The process of enzyme immobilization under the diffusion-controlled regime (i.e., fast attachment of enzyme compared to its diffusion) is modeled and theoretically solved in this article. Simple and compact solutions for the penetration depth of immobilized enzyme and the bulk enzyme concentration versus time are presented. Furthermore, the conditions for the validity of our solutions are also given in this article so that researchers can discover when the theoretical solutions can be applied to their systems.
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  • 52
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    Biotechnology and Bioengineering 26 (1984), S. 1026-1031 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: After transforming host cells of Bacillus stearothermophilus CU21 with a recombinant plasmid pLP11 that harbored constitutive penicillinase genes of B. licheniformis CO1, both the stability of the plasmid and specific rate of penicillinase production were studied. The temperature at which the plasmid could be kept in a stable fashion in the transformant of B. stearothermophilus CU21 (pLP11) ranged nearly from 44 to 50°C, irrespective of batch and continuous cultures. Continuous and steady-state cultures of the transformant could only be realized within this narrower temperature range. Indeed, the approximate temperature ranges of growth for the host and transformant were from 40 to 70°C and from 40 to 63°C, respectively. Clearly, the upper limit for the growth temperature of host cells decreased when they were transformed. Kinetic patterns of penicillinase production in continuous culture of the transformant (with plasmid) from 44 to 50°C differed remarkably from that of B. licheniformis CO1 (without plasmid) at 37°C.
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  • 53
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    Biotechnology and Bioengineering 26 (1984), S. 1066-1070 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effectiveness of attaching flavin adenine dinucleotide (FAD) via a C bridge to Teflon-bonded carbon black (CB), and the subsequent immobilization of glucose oxidase on the FAD-modified electrodes has been studied by cyclic voltammetry. When FAD alone is bound to the electrode, it undergoes reduction and oxidation at -0.62 and -0.5 V, respectively - values similar to those obtained with free FAD. Compared to the free enzyme, the reduction of FAD as part of the immobilized enzyme is 200 mV more cathodic, while the oxidation potential remains the same in both cases.
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  • 54
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    Biotechnology and Bioengineering 26 (1984), S. 1079-1084 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In search of hypercellulolytic microorganisms, ultraviolet irradiation carried out with Penicillium funiculosum has yielded a superior mutant. The investigations reported in this article are shake flask studies on some important nutritional requirements of the mutant, namely, nitrogen source, carbon source, and inducers. The mutant shows an ability to metabolize inorganic nitrogen sources like urea and sodium nitrate both for growth and enzyme production. A comparison of the long-term saccharification ability and the utilization efficiency of the mutant enzyme with those reported in the literature is also carried out, showing the superior performance of the mutant enzyme.
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  • 55
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    Biotechnology and Bioengineering 26 (1984), S. 1090-1097 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Electron paramagnetic resonance (EPR) spectroscopy has been applied in concert with measurements of catalytic activity and the quantity of active immobilized protein to study the deactivation in 50% n-propanol of α-chymotrypsin immobilized on CNBr-Sepharose 4B. These analyses focus on the behavior of two distinct active forms of immobilized enzyme, designated here A and B, identified in previous studies. Raw data provided by EPR spectroscopy clearly show that the relative quantities of active chymotrypsin-A and active chymotrypsin-B change as a result of exposure to alcohol, with the relative quantity of the B form increasing with time. These and additional results provide evidence that the distribution of A and B forms is a function of active enzyme loading but independent of the means used to obtain the loading. Different kinetic models in conjunction with experimental observations consistently indicate that the activity of enzyme form B, by far the more active enzyme form, does not change significantly during the initial 60 min of catalyst deactivation but then decreases appreciably.
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  • 56
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    Biotechnology and Bioengineering 26 (1984), S. 1108-1113 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The hydrocarbon metabolizing Acinetobacter calcoaceticus sp. 2CA2 reduces the surface tension of the culture broth during growth on liquid hydrocarbons. This activity, which is not evident during growth on soluble substrates, is associated with the whole cells. Removing the cells from the culture broth increases the surface tension of the liquid phase. The cells when resuspended in water result in a dramatic lowering of the surface tension. Acinetobacter sp. 2CA2 tends to partition between the two liquid phases during growth on hydrocarbons. Both the hydrocarbon bound and nonadhering cells are equally surface active. The whole cells are also able to form and stabilize kerosene-water emulsions. This ability is not related to the lowering of the liquid surface or interfacial tension, since both surface active and nonsurface active cells demonstrated the same emulsifying properties. An extracellular lipopeptide produced during growth on hydrocarbons is not surface active but effectively forms and stabilizes kerosene-water emulsions. The cells and extracellular lipoptide are also effective in de-emulsifying surfactant stabilized test emulsions. The lipopeptide product reduced the half-life of a Tween-Span (TS) stabilized kerosene-water emulsion from 650 to 0.4 h at product concentrations of less than 1% (w/v).
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  • 57
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    Biotechnology and Bioengineering 26 (1984), S. 1128-1130 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 58
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    Biotechnology and Bioengineering 26 (1984), S. 1131-1133 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 59
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    Biotechnology and Bioengineering 26 (1984), S. 1383-1389 
    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 based on molecular mechanisms for regulation of the lactose (lac) operon in Escherichia coli has been extended and applied to investigate the lac promoter function in the chromosome and in multicopy plasmids. The model simulates the influence of certain host cell mutations and also mutations in the lac promoter sequence in the chromosome in reasonable agreement with previous experimental measurements. The effect of the plasmid copy number and the cloning vector size on the promoter function of a cloned lac regulatory sequence in multicopy plasmids has also been examined. Model results indicate that the efficiency of the cloned lac promoter function is significantly decreased as the number of promoters per cloning vector and size of the vector are increased. The simulation results predict a maximum in the cloned gene transcription rate with respect to the plasmid copy number.
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  • 60
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    Biotechnology and Bioengineering 26 (1984) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 61
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    Biotechnology and Bioengineering 26 (1984), S. 1245-1251 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The forces required to remove living, fully attached barnacles from the surface of a number of polymeric solids were measured. The forces were related to the surface energy components of the materials. The results indicate a positive correlation between polymer surface energy and force required for barnacle removal. The nonpolar component of the surface energy was more closely related to the removal force than the polar component, although the polar component is significant. Adherence to some composite materials was greater than was consistent with the correlation for noncomposites.
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  • 62
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    Biotechnology and Bioengineering 26 (1984), S. 1252-1257 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Wheat straw (Ws)was treated in a pilot-scale continuous mixer to disrupt the lignin-hemicellulose-cellulose (LHC) complex. An efficient and practical method was desired to remove lignin and hemicellulose (pentosans)rapidly and efficiently from the lignocellulose complex and to make the cellulose accessible to enzymatic hydrolysis. Milled WS in the presence of various chemicals in aqueous solutions was extruded from the mixer under several processing conditions. Chemicals used were sodium hydroxide (NaOH) sodium sulfide (Na2S), anthraquinone (AQ), anthrahydroquinone (AHQ), hexamethylenediamine (HMDA), hexamethylenetetramine (HMTA) hydrogen peroxide (H2O2), and ferrous ammonium sulfate (FAS), which were used alone and in selected combinations. Concomitantly, WS was treated in laboratory batches using similar reaction conditions, except for mixing and shearing. In extrusion treatments of WS at 20% concentration at 97°C for 5.5 min with NaOH (15.7%, dry WS basis), NaOH (15.7%) + AHQ (0.3%), and NaOH (12.7%) + Na2S (5.0%), 64-72% of the WS lignin and 36-43% of the pentosans were removed from aqueously washed extrudates (residues). This compares with 46-56% and 23-27%, respectively, for batch treatments. AHQ and Na2S enhanced delignification. Cellulase treatment of the residues, which contained about 99%of the WS cellulose, converted 90-92%of the cellulose to glucose compared with 61-69%for the batch pretreatments. Treatments of WS with amines and H2O2 (alone or combined with NaOH)were less effective for LHC disruption. In all instances the relatively high-shear extrusion treatments were superior to the laboratory-batch treatments.
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  • 63
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    Biotechnology and Bioengineering 26 (1984), S. 1288-1293 
    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 achieve synchronization of cell division by continuous phasing, the growth of enteric bacteria has been limited by inorganic phosphate. After a short starvation, the culture was automatically diluted twofold so that the limiting nutrient allowed for one doubling exactly. An automatic device was designed to carry out repeated cycles of growth, starvation and dilution with adjustable periodicity. After 12-24 automatic cycles, which were usually achieved largely overnight, synchronous cell divisions could be observed for several generations in nonlimiting culture conditions. When portions of the phased culture were frozen and kept at low temperature for periods up to several months, these freeze-preserved populations exhibited a synchronous growth upon thawing and cultivation. This technique has thus the potential of providing synchronized cultures of a variety of bacterial strains at the desired time.
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  • 64
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    Biotechnology and Bioengineering 26 (1984), S. 1323-1329 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Nonliving biomass of nine Rhizopus species effectively sequestered the uranyl ion from solution, taking up 150-250 mg U/g dry cells at 300 ppm U equilibrium concentration in solution, and 100-160 mg U/g dry cells with 100 ppm U in solution. The affinity of this biosorbent for the uranyl ion was found to be affected by timing of harvesting and medium composition. Uptake of the uranyl ion by nonliving biomass of Rhizopus oligosporus was due to ion exchange or complexation, since binding was reversed by the addition of complexing ligands or the reduction of pH to a value less than 2. Uptake isotherms were interpreted in terms of a model of multiple equilibria. At pH ≤ 2, or in the presence of NO3-, Cl-, SO42-, or EDTA (ethylenediamine-tetra-acetate), the quantity of UO22+ that was bound was a constant fraction of that bound at pH 4 in the absence of ligands. This action indicated simple competition for uptake sites between H3O+ and UO22+ for uptake sites, or for UO22+ between the biomass and ligands in solution. If oxalate or thiocyanate was present, however, the complexed species were sequestered by the biomass. Biomass of Rhizopus arrhizus, which grew as pellets, was subsequently used in a packed sorption column where it exchanged hydrogen ions for uranyl ions (2 H+: 1 UO22+). Concentrated uranyl solutions were eluted in sulfuric or nitric acids, and the biomass was reused eight times with no apparent deterioration of the biosorbent.
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  • 65
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    Biotechnology and Bioengineering 26 (1984), S. 320-327 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The kinetics of crystalline cellulose and hemicellulose hydrolysis in corn stover were studied with a nonisothermal technique. Reactions were arrested at temperatures between 160 and 240°C and product sugars were analyzed using a Bio-Rad HPX-85 liquid chromatographic column. A simple first-order series reaction model was used for both cellulose and hemicellulose hydrolysis reactions. Kinetic parameters were obtained for three different sulphuric acid concentrations (0.49, 0.92, and 1.47 wt %). Activation energies remained constant over this acid concentration range but the preexponential factors showed an increase with acid concentration. Relationships were obtained between the preexponential factors and acid concentrations. Cellulose hydrolysis and glucose degradation reactions were observed to be of higher order with respect to acid concentration in comparison with the previous studies with other raw materials.
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  • 66
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    Biotechnology and Bioengineering 26 (1984), S. 434-441 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fungi of the Aspergillus sp. can hydroxyate biphenyl to 4,4′-dihydroxybiphenyl, a chemical intermediate used in the plastics industry. The authors studied various batch culture conditions for the production of 4,4′-dihydroxybiphenyl, by Aspergillus toxicarius, in 25-mL shake flasks and 2-L fermenter cultures. Conditions investigated included temperature, aeration, carbon and nitrogen sources, biomass content, and time of substrate addition. Under optimum conditions we observed a rate of 4,4′-dihydroxybiphenyl production of 15-20 mg/day/g dry wt mycelia. Such a production rate is probably too low to support a commercial process and possible reasons for the low productivity are discussed.
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  • 67
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    Biotechnology and Bioengineering 26 (1984), S. 17-21 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The cellulase production from immobilized Trichoderma reesei composites prepared by radiation polymerization at low temperature was studied. The production of cellulase from the cells irradiated by radiation was slightly retarded at the initial stage of the culture, but was immediately recovered. The production of cellulase resulting from the growth of the immobilized cells proceeds efficiently in the composite having a porous polymer matrix, in which the productivity of cellulase varied with the hydrophilicity, the shape of the composite, monomer, and cell concentration. It was found that cellulase produced by immobilized growing cell composites effectively hydrolyzed cellulosic wastes such as newspaper and chaff which are pretreated by irradiation and crushing.
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  • 68
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Proline excretion from proline overproducing strains of E. coli K12 has been studied as a model chemical production system. We have isolated proline overproducing mutants of E. coli and have shown that uncontrolled synthesis is not sufficient to cause excretion of this amino acid. An episomal mutation causing proline over production has been introduced into a series of otherwise isogenic strains that bear well defined, chromosomal lesions affecting the active uptake and catabolism of L-proline. A syntropism test reveals that L-proline is excreted by overproducing strains only if transport and/or catabolism are impaired. Dansyl derivatization and chromatographic analysis of culture supernatants shows that proline is the only amino acid excreted. Batch cultures of an excreting strain in an amino acid production medium yield culture supernatants containing 1 g proline/L, whereas no proline is detectable in supernatants derived from cultures of an overproducing strain with normal transport and catabolic activities. These data reveal that genetic lesions eliminating active uptake can be used to specifically enhance metabolite excretion.
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  • 69
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    Biotechnology and Bioengineering 26 (1984), S. 100-103 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 70
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    Biotechnology and Bioengineering 26 (1984), S. 128-133 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pichia polymorpha has inulinase activity and could be used for the production of fructose syrup from inulin. The application of immobilized P. polymorpha whole cells for the continuous hydrolysis of inulin is, however, limited since the biosynthesis of this enzyme system is repressed by the reaction products, dextrose and fructose. A derepressed mutant hyperproducer of inulinase was isolated after treatment with EMS followed by a selection step with deoxyglucose.
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  • 71
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    Biotechnology and Bioengineering 26 (1984), S. 148-155 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Butanediol production by Aerobacter aerogenes NRRL B199 grown on glucose requires an optimal rate of aeration for the obtention of butanediol 2, 3. In the absence of air, Aerobacter aerogenes NRRL B199 growth and production are weak. Agitation-aeration is necessary for producing the biomass, but an excess of oxygen proves to be toxic with regard to metabolite production. Oxygen is a limiting substrate with regard to growth and an inhibitor with regard to the specific metabolite productivity. This observation is discussed from a kinetic stand point and in relation to the search for the optimum oxygen transfer coefficient (KLa), which is found to be in the range of 50-100h-1. It has also been observed that KLa increases during the fermentation cycle. The initial substrate concentration effects the yield production of biomass and butanediol production. Low yields of butanediol are obtained at low initial sugar concentrations, but good yields of butanediol are obtained (0.45 g/g) at high concentrations of glucose (195 g/L). Carbon substrates and butanediol are inhibitors of cell growth while butanediol is not quite an inhibitor of the specific rate of butanediol production for the range of butanediol of 0-100 g/L.
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  • 72
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    Biotechnology and Bioengineering 26 (1984), S. 174-187 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A stoichiometric equation has been derived which describes the interrelations among the various products and biomass in fermentations of butyric acid bacteria. The derivation of the equation is based on an assumed ATP yield, two biological regularities, and the biochemistry of product formation of the fermentations. The equation obeys the constraints imposed on growth and product formation by thermodynamics and the biochemical topology. The validity of the equation is tested using a variety of fermentation data from the literature. The uses, improvements, limitations, and extensions of the equation are also discussed in detail. For example, the fermentation equation is used to calculate the maximal possible yields of the main fermentation products.
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  • 73
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    Biotechnology and Bioengineering 26 (1984), S. 231-238 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Direct evidence was obtained for the existence of two distinct forms of active α-chymotrypsin immobilized on CNBr-activated Sepharose 4B. Electron paramagnetic resonance (EPR) spectra of five different spin-labeled immobilized enzyme formulations in the presence of indole were all resolved into the same two spectral components. Both subpopulation spectra were approximately identified experimentally, and the subpopulation exhibiting greatly restricted spin-label motion was shown also to be relatively inaccessible to solvent. Using overall specific activity data and subpopulation fractions from EPR spectral analysis, the specific activity of the more constricted immobilized enzyme active form was shown to be approximately 15 times smaller than that of the other class of immobilized enzyme molecules with an indole EPR spectrum similar to that of chymotrypsin in solution. Variations in overall specific activity of formulations with different loadings and different supports results entirely from changes in the proportions of the same two subpopulations of immobilized enzyme molecules.
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  • 74
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    Biotechnology and Bioengineering 26 (1984), S. 239-246 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biomass has been produced from glucose using the organism Zoogloea ramigera 115. This biomass has been used to remove copper, cadmium, and uranyl ions from water solutions. The metal uptake was studied with two different methods: either by spectrophotometric measurements on the solutions after flocculation or by potentiometric measurements with amalgam electrodes in order to follow the entire complex formation. The metal-biopolymer interaction in 0.1M NaClO4 is practically the same as when no neutral salt is added. The metal uptake is dependent on pH and is selective. A reversible process suitable for metal complexation is described.
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  • 75
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    Biotechnology and Bioengineering 26 (1984), S. 452-456 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Purified human α1 proteinase inhibitor, a plasma glycoprotein with a molecular weight of 5.3 × 104 daltons and a major serine protease inhibitor has been covalently coupled to dextrans with molecular weights of 1.77 × 104 and 1.03 × 104 daltons. The coupled conjugates were soluble in aqueous medium and stable up to 6 months at +5°C. Increased moles of dextran/mole protein ratio during coupling resulted in progressive decreases of inhibitory capacity, immunogenicity, and the association constant (kassoc) between the enzyme and the inhibitor. Compared to the native protein, the soluble conjugates showed improved stability at pH 3.0 and heat stability at 60°C. At 60°C, no loss of inhibitory capacity has been seen up to 60 min for the conjugates during which time the native protein lost greater than 90% of its inhibitory capacity. The presence of antioxidant catalase was needed to prevent oxidative degradation by hydrogen peroxide.
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  • 76
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    Biotechnology and Bioengineering 26 (1984), S. 477-480 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Effluent from the caustic extraction stage of a bleach plant is highly colored due to the presence of dissolved products from lignin chlorination and oxidation. Color removal from the effluent by hydrogen peroxide at neutral pH was catalyzed by addition of horseradish peroxidase. The catalysis with peroxidase (20 mg/L) was observed over a wide range of peroxide concentrations (0.1mM-500mM), but the largest effect was between 1mM and 100mM. The pH optimum for catalysis was around 5.0, while the basal rate of noncatalyzed peroxide color removal simply increased with pH within the range tested (3-10). Peroxidase catalysis at pH 7.6 reached a maximum at 40°C in 4 h assays with 10mM peroxide, and disappeared above 60°C. Compared with mycelial color removal by Coriolus versicolor, the rate of color removal by peroxide plus peroxidase was initially faster (first 4 h), but the extent of color removal after 48 h was higher with the fungal treatment. Further addition of peroxidase to the enzyme-treated effluent did not produce additional catalysis. Thus, the peroxide/peroxidase system did not fully represent the metabolic route used by the fungus.
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  • 77
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    Biotechnology and Bioengineering 26 (1984), S. 426-433 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Alkali treatment and steam explosion of bagasse were investigated in order to develop economical and effective methods of increasing the digestibility of bagasse. The treated bagasse was to be used as a substrate for the production of volatile fatty acids by anaerobic acidogenic bacteria. The alkalis examined were NaOH, NH3 (aqueous), NaOH + NH3, Ca(OH)2, and Ca(OH)2 + Na2CO3, at ambient temperature and in combination with steam explosion at 200°C, 6.9 MPa, and 5 min cooking times. Digestibilities of up to 733 g organic matter (OM)/kg bagasse dry matter (DM) were obtained for bagasse treated with NaOH and Ca(OH)2 + Na2CO3; less than 430 g OM was obtained for bagasse treated with aqueous NH3; and up to 724 g OM was obtained for bagasse treated with Ca(OH)2. This digestibility was only achieved by using high concentrations of Ca(OH)2, i.e., 180-300 g/kg bagasse. Steam explosion increased the digestibility of bagasse up to 740 g OM in the presence of alkali but only to 610 g OM in the absence of alkali. The digestibility of bagasse without pretreatment was 190 g OM/kg bagasse DM. More than one-half the hemicellulose present was solubilized by pretreatment. The composition of the liquid fraction of steam-exploded material was examined and contained mainly xylose monomers and oligomers (112 g/kg original bagasse DM) and acetic acid (33 g/kg original DM). The relative costs of the alkalis used were obtained for the United States, Australia, and Europe. Lime [Ca(OH)2] was the least expensive alkali per unit of additional digestible OM obtained. Ammonia was the most expensive alkali to use, except in the United States where the difference in its cost relative to other alkalis was smaller. However, ammonia provides organic nitrogen for microbial growth, and could be recycled. With acidogenic fermentations, alkali is able to double as a neutralizing agent during fermentation. Thus, concentrations of alkali equal to that required for neutralization may be used in pretreatment. Concentrations of Ca(OH)2 as high as 300 g/kg bagasse were needed for neutralization and should, therefore, be considered for pretreatment. Steam explosion of bagasse resulted in digestible, sterilized substrates of small particle size with readily separable liquid and pulp streams.
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    Biotechnology and Bioengineering 26 (1984), S. 508-512 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Addition of microcarrier beads to a matrix perfusion cell culture system allowed growth of anchorage dependent human foreskin fibroblasts which would not grow in the culture units alone. The utility of the system for collection of cellular products was demonstrated by the induction and harvesting of human (β) interferon. Interferon production was highest in perfusion cultures when medium was circulated throughout the induction and when inducer containing 100 μg/mL polyriboinosinic: polyribocytidylic acid was placed directly in contact with cells in the extracapillary space. These conditions provided 4-to-10-fold greater interferon yields per cell, and approximately 12-fold increases per vessel, than monolayer cultures. Perfusion grown cells produced interferon at a maximal level for 20 h postinduction compared to approximately 2 h for monolayer grown cells, thus giving a higher total yield of interferon. Other procedures increasing the efficiency of the system included priming with 50 U/mL interferon standard, reinduction of cells, use of antibiotic free medium, reduced serum concentrations, and in vitro aging of the cells.
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    Biotechnology and Bioengineering 26 (1984), S. 544-545 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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    Biotechnology and Bioengineering 26 (1984), S. 623-626 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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  • 81
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Biotechnology and Bioengineering 26 (1984) 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 83
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    Biotechnology and Bioengineering 26 (1984), S. 665-669 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Single- and double-stranded DNA were immobilized on films of highly polymerized collagen by a covalent process. The coupling was efficient at an acidic pH with an optimum at pH 5, while preventing the collagen film from any damage. In addition, no leakage occurred, so it was possible to use this DNA-coated collagen film as an immunoadsorbent. Therefore the findings reported here suggest that the acyl-azide procedure is also suitable for DNA binding on a proteinic support. Promising results in specific clearance of DNA antibodies were obtained in vitro.
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    Biotechnology and Bioengineering 26 (1984), S. 677-681 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Chlorella sp. strain VJ79 was isolated from a total heterotrophic count of a wastewater collector. It grows autotrophically, heterotrophically, and mixotrophically on a variety of organic substrates. Glucose and serine promote a mixotrophic growth from which the yield is higher than the sum of autotrophic and heterotrophic yields, but serine assimilation requires light. The interaction of glucose and light was studied in proliferating and nonproliferating cells by respirometry (IRGA and Warburg) and growth experiments. Glucose inhibits the photosynthetic CO2 fixation ten-fold and modifies the pigmentary system as it does in heterotrophic cultures. Light inhibits glucose uptake and assimilation, but under mixotrophic conditions maximal utilization of glucose is obtained. Mutants defective in autotrophic growth were isolated by mutagenesis with nitrosoguanidine. They show a degenerated pigmentary system and a mixotrophic growth yield equal to that of the heterotrophic growth. The analysis of the mixotrophic system shows that light energy, dissipated during autotrophic growth, is used under mixotrophic conditions. From the increase in growth, the increase in photosynthetic efficiency can be calculated as ca. sixfold.
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    Biotechnology and Bioengineering 26 (1984), S. 714-718 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Culture filtrates of Talaromyces emersonii UCG 208 grown on beet pulp can convert the polysaccharide components of this agricultural waste to soluble sugars. The saccharification process is facilitated if the pulp is milled or incubated with alkali or peracetic acid before addition of enzyme. However, treatment of unmilled pulp with commercial pectinase prior to incubation with Talaromyces filtrate is also very effective; under suitable conditions, complete hydrolysis of total polysaccharides has been achieved.
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 719-726 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The influence of methanol dispersion and fluid mixing upon respiratory patterns observed during unlimited fedbatch growth of the methylotrophic bacterium Methylophilus methylotrophus has been investigated. A concentric tube air-lift fermenter was employed for which the mixing and fluid circulation patterns have been well characterized. Respiratory quotients showed a marked dependence upon the position in the vessel at which methanol was injected, the volumetric rate of such methanol addition, the fluid circulation time, and the local mixing behavior; the latter two factors of which are both determined by the air throughput. Such variations are discussed on the basis of simple mixing concepts and observations of fluid dispersion.
    Additional Material: 10 Ill.
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  • 87
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 753-757 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The products of cellulose hydrolysis, glucose and cellobiose, caused noncompetitive inhibition patterns to be exhibited when Thermomonospora sp. YX cellulase hydrolyzed dyed cellulose. The glucose binding constant, β1, was 0.00683 ± 0.00031 L/g and the cellobiose binding constant, β2, was 0.095 ± 0.0058 L/g. Thus, cellobiose was about 14 times more inhibitory than glucose.
    Additional Material: 8 Ill.
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  • 88
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 764-770 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The hydrogen-oxidizing bacterium, Alcaligenes eutrophus (ATCC 17707), was grown in chemostat culture with gas-phase (hydrogen, oxygen, and carbon dioxide) and liquid-phase (mineral nutrients) feedstreams; data were used to generate an analytical form for the specific growth rate equation. Model parameters obtained include Monod rate parameters for dissolved hydrogen and oxygen gases, yield coefficients, and specific maintenance rates under conditions of hydrogen or oxygen limitations. These values are similar to some obtained previously by Ohi et al. for another hydrogen bacterium. The observed increase in specific maintenance rates under hydrogen-versus-oxygen-limited culture may be associated with hydrogenase deactivation by oxygen.
    Additional Material: 8 Ill.
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  • 89
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 771-774 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The efficiency of β-glucosidase and Saccharomyces cerevisiae in directly converting cellobiose to ethanol was studied for various combinations of the two catalytic species, both free and immobilized, in order to elucidate the advantages of using a coimmobilized system. The coimmobilized preparation was superior to a combination of separately immobilized biocatalysts. However, in this preparation, one-half the enzyme activity was lost within a week when incubated at the operational temperature in the absence of substrate. In continuous experiments, an 80% conversion of cellobiose to ethanol was obtained using the coimmobilized preparation, compared to 40% using separately immobilized biocatalysts when applying a dilution rate of 0.1 h-1 in a packedbed reactor. The immobilized biocatalysts showed no decline in productivity during two weeks of continuous operation.
    Additional Material: 3 Ill.
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  • 90
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 788-796 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A washed carrot substrate, prepared with high yields and easy handling properties, was found to be a suitable substrate for studying cellulolytic and pectinolytic degradation processes. A cellulase from Trichoderma reesei, and Rohament P, a macerating enzyme from Aspergillus alleaceǔs in endopolygalacturonase, degraded the washed carrot substrate to an extent of 60%. With the combined action of both enzymes, degradation was more than 80%. Simultaneous action of both enzymes was more efficient than their sequential use. The effect of temperature, pH, incubation time, enzyme concentration, and substrate concentration on the degradation by the single enzymes and their mixture were studied. Gas chromatographic sugar analysis revealed that Rohament P liberated glucose, arabinose, and galactose in the low-molecular-weight fraction obtained by ultrafiltration, in addition to high amounts of galacturonic acid. These carbohydrates were also found in the high-molecular-weight fraction (retentate) together with rhamnose and mannose. Cellulase BC released mainly glucose, although galacturonic acid, arabinose, xylose, and mannose were also detected both in the ultrafiltrate and retentate. Morphologically, during Rohament P degradation of the washed carrot substrate, damaged tissues and disintegrated cells were seen, whereas on cellulase BC action mainly disintegrated cell walls were observed.
    Additional Material: 9 Ill.
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  • 91
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 807-810 
    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.
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  • 92
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1227-1232 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dihydrofolate reductase, purified to homogeneity from amethopterin-resistant Lactobacillus casei, was immobilized by coupling to cyanogen bromide-activated Sepharose or carbodiimide-activated CH-Sepharose. Coupling yields were determined by amino acid analysis following the hydrolysis of the gel. Enzyme activity was measured by the conventional spectrophotometric procedure, thus permitting the facile characterization of the immobilized enzyme. The pH optimum of the immobilized enzyme was shifted to 5.8 compared with pH 5.5 for the soluble enzyme. The immobilized enzyme retained greater than 90%of the initial activity over a six-month period and could be reused as many as ten times without loss of activity. As observed with the soluble enzyme, the activity of immobilized enzyme, which was lost on denaturation with 4M guanidine hydrochloride, was recovered rapidly and completely by washing the gel with buffer. The Kmapp values for dihydrofolate and NADPH for the immobilized enzyme were increased 15-164-fold over the Km values measured for soluble dihydrofolate reductase. Scatchard analysis of the interaction of amethopterin with the immobilized enzyme yielded linear plots and a Kdapp value of 0.56 ×10-8M, and revealed that all of the immobilized enzyme molecules were capable of binding the ligand.
    Additional Material: 6 Ill.
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  • 93
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1258-1260 
    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.
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  • 94
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1272-1281 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The internal regulatory processes, which underlie a variety of behavior in microbial growth on multiple substrates, are viewed as a manifestation of an invariant strategy to optimize some goal of the cells. A goal-seeking or cybernetic model is proposed here, with the optimization obased on a short-term perspective of response to the environment. The model parameters are determined from the growth data on single substrates. The model predicts the entire range of microbial growth behavior on multiple substrates from simultaneous utilization of all sugars to sequential utilization with pronounced diauxic lags. It is shown to predict the many variations of the diauxic phenomenon in different growth conditions. The transients in continuous culture growth on mixed substrates caused by varying the feed strategies are easily simulated by this model. The framework of this model can be applied to batch or continuous culture growth of many bacteria on different combinations of substrates.
    Additional Material: 11 Ill.
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  • 95
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1294-1305 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Oil residues arising from the Christos-Bitas spillage were found to contain 28% of oil extractable by carbon tetrachloride; the remainder comprised water and undefined solids. When incubated in 8-L rectangular tanks with a mixed population of mainly bacteria to which diammonium hydrogen phosphate was added, ca. 97% of the Christos-Bitas oil fraction was degraded. When the same substrate was degraded by only three isolated Pseudomonas strains in 1-L cylindrical tanks, degradation was only ca. 56%. Raising the temperature from 20 to 50°C brought about a visible loss in cell viability with only ca. 38% of the substrate degraded. Oil degradation proceeded in direct proportion to increases in cell attachment to the dispersed oil. The aliphatic fraction of Kuwait crude oil up to nC25 measured by gas liquid chromatography (GLC) was oxidized within 48 h. Using this substrate the three pseudomonads together brought about a more complete degradation (87%) than a single Bacillus isolate. The Bacillusstrain was capable of deggrading between 50 and 65% of the crude, depending on whether diammonium hydrogen phosphate supplemented a peptone-based medium. The preferential biodgradability of fractions was the following aliphatics 〉 aromatics 〉 asphalts, as has been widely reported.
    Additional Material: 6 Ill.
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  • 96
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1330-1333 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mercury-resistant bacteria, which are able to reduce mercuric ion (Hg2+) to metallic mercury (Hg0), were examined for their ability to remove mercury from waste-water aerobically. Growth studies in artificial medium indicated that mercury increases the lag phase, but does not effect the growth rate of these bacteria. Further studies demonstrated that growth was minimal during a phase of rapid mercury removal, after which growth resumed. Small but significant amounts of carbohydrates are required for the mercuric ion reduction. Prolonged periods of bacterial growth under nonsterile conditions was accomplished without the loss of the mercuric reducing ability of the culture. A continuous culture of the resistant organism was maintained on raw sewage for two weeks, during which time relatively high concentrations of mercury (70 mg/L) were removed from the sewage at a rate of 2.5 mg/L h and at efficiencies exceeding 98%.
    Additional Material: 2 Ill.
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  • 97
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1364-1371 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Flavin adenine dinucleotide (FAD) and glucose oxidase were adsorbed on medium porosity spectroscopic graphite (SG) and on low porosity glassy carbon (GC) with retention of electrochemical activity, as measured by cyclic and differential pulse voltammetry. Adsorption on the SG was very strong, while that on GC was much weaker. Enzyme activity could be partially restored by the addition of the apoenzyme of glucose oxidase to the SG-adsorbed FAD preparation. The holoenzyme of glucose oxidase also was adsorbed on SG with retention of enzyme activity. The mechanism for the reconstitution of active enzyme from adsorbed FAD and soluble apoenzyme is not clear. The data suggest that the reconstituted enzyme stays adsorbed to the SG, but it is not clear whether the FAD or protein portions (or both) are adsorbed after reconstitution. The data also indicate that substrate mass transfer resistance may be important with the reconstituted-adsorbed enzyme.
    Additional Material: 7 Ill.
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  • 98
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 948-958 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Time-dependent biofilm formation effects on continuous fermenter operation are modelled here in general for a mixed culture of N different microorganisms growing on a single substrate. Dynamic computer solutions are detailed for two versions of the general model: a pure culture and a simple two-cell mixed culture. Pure culture model predictions compare favorably with two pure culture experiments in the literature where significant biofilm formation was noted. A mixed culture of one microbe (C1) having a higher growth rate than a second microbe (C2) is simulated for two hypothetical scenarios of microbe C2 having different magnitudes of cell deposition rate. Biofilm effects on the estimation of kinetic and stoichiometric parameters in both model versions, plus the impact of biofilms on mixed culture dynamics, are discussed.
    Additional Material: 12 Ill.
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  • 99
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1455-1464 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The yield from glucose of ammonia-grown carbon-limited continuous cultures of Penicillium stipitatum was ca. 20% higher than that of nitrate-grown cultures at all growth rates examined. However, the yield from oxygen was similar during growth on both nitrogen sources. Under phosphate limitation the specific rate of gluconic acid and stipitatic acid production increased with growth rate, but the former product accounted for virtually 100% of the excreted carbon. Stipitatic acid was not produced under nitrogen limitation, and glucose supplied to the culture in excess of that required for growth was virtually quantatively converted into gluconic acid. Productivities of 11.4 g gluconic acid/L/h were stably maintained in continuous culture. Under conditions of glucose excess the enzyme glucose oxidase was excreted into the culture. The specific activity of this extracellular enzyme increased when the input glucose concentration to the culture was progressively increased. The excretion of a protein under nitrogen limitation suggests that this enzyme plays an important role under these conditions. Indeed, it was demonstrated that nitrogen-limited cultures did not overmetabolize gluconate at either pH 6.5 or 3.5, although up to 29 g/L gluconate was present in the culture. The Ygluconate and YO2 of C- and N-limited gluconate-grown cultures were similar indicating that the rapid conversion of glucose to gluconate probably affords a means of regulating carbon flow in this organism. Nitrogen-limited cultures of P. stipitatum overmetabolized glucose to a much greater extent than acetate, fructose, or gluconate.
    Additional Material: 3 Ill.
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  • 100
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1176-1188 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An integrated approach is presented for the on-line estimation of the state of a biochemical reactor from presently attainable real-time measurements. Elemental and macroscopic balances are used for the determination of the total rate of growth and state-of-the-art estimation techniques are subsequently employed for the elimination of process and measurement noises and the estimation of state variables and unknown culture parameters. The proposed approach is very flexible in that as new sensors become available they can be easily incorporated within the present framework to estimate new variables or improve the accuray of the old ones. The method does not require any model for the growth kinetics and is very successful in accurately estimating the above variables in the presence of intense noise and under both steady-state and transient conditions. State estimates obtained by the presented method can be used for the development of adaptive optimal control schemes as well as for basic studies of the characteristic properties of microbial cultures.
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