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  • 1980-1984  (328)
  • 1982  (328)
  • Biochemistry and Biotechnology  (328)
  • Nuclear reactions
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982) 
    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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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 25-36 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Whole cells of Alcaligenes eutrophus (as well as isolated P. oxalaticus formate dehydrogenase and A. eutrophus hydrogenase coupled via NAD+ or methyl viologen) have been shown to produce H2 from formic acid. Immobilization of the cells in kappacarrageenan gel greatly enhances their stability at room temperature. The rate of hydrogen production catalyzed by immobilized A. eutrophus has been studied as a function of the concentrations of the cells and formate and also pH. An inhibition by high concentrations of formate has been found. Immobilized cells were also capable of synthesizingformate from H2 and bicarbonate. Yields of formate up to 30% have been obtained. The catalytic efficiency of immobilized A. eutrophus cells was compared with that of palladium adsorbed on activated carbon.
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  • 3
    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 mixing duration and vacuum on methane production rates from anaerobically fermented beef cattle wastes were discussed. The results showed that continuously mixed fermentors produced significantly (P 〈 0.05) higher methane production rates than fermentors mixed two hours per day. However, the rates from the continuously mixed fermentors were only 8-11% higher than the intermittently mixed fermentors at six and four days hydraulic retention time (HRT), respectively. There was no significant difference between the vacuum and conventional fermentors at six days HRT, but there was a significant difference at four days HRT. The CH4 production rate of the vacuum fermentors was 5% higher than the conventional fermentors at four days HRT. The results of these experiments compared well with predicted CH4 production rates. These results suggest that there is little potential for increasing the fermentation rates of livestock wastes by increased mixing or vacuum.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 1-7 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of several factors on the activity and stability of alcohol dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, and 20β-hydroxysteroid dehydrogenase, both free and immobilized on CNBr-activated Sepharose 4B, was investigated. Enzymes were im- mobilized under different conditions including various degrees of matrix activation, variable amounts of protein, in the presence, or in the absence of, additives (coenzymes, dithioth- reitol, salts). Activity recovery was in general satisfactorily high with 20β-hydroxysteroid dehydrogenase, low with glyceraldehyde-3-phosphatedehydrogenase, and markedly linked to the concentration of immobilized protein with alcohol dehydrogenase. In the latter case the advantageous stabilizing effect of high enzyme concentrations was notably diminished by the parallel decrease of the effectiveness factor. The effect of high concentrations of anions of the Hofmeister series was examined. It was found that 1M phosphate and 0.5M sulfate dramatically stabilize both free and immobilized enzymes against inactivation by temperature and urea. Km, values of apolar substrates were considerably lowered by the two anions while Km values of polar substrates were not affected. In some cases Vmax values also were influenced by high concentrations of these anions. The present results appear of interest particularly in view of enzyme utilization for analytical as well as for preparative purposes.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 37-55 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model for noninhibitory microbial growth has been developed which is superior to the Monod model in that it can predict the decline in steady-state growth yields at both the slow and the fast specific growth rates. The model parameters are evaluated from data obtained for steady-state, phenol-limited Pseudomonas putida growth using a conventional 1-dm3 cheniostat. The model also has been successfully applied to Mor and Fiechter's data for cheniostat yeast cultures.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 57-68 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The feasibility of producing ethanol in a continuous system from cellulose using Clostridirrrn thermocellum was investigated. This anaerobic and therniophilic bacterium was able to degrade cellulose directly into ethanol with acetic acid, hydrogen. and carbon dioxide as by-products of this fermentation. The fermentation was first carried out in a batch mode to study the effects of buffers, temperature, and agitation on microbial growth and ethanol production. From the compounds used to control pH. sodium bicarbonate had the most preferred effects on generation time and ethanol production. As expected, there was a positive relationship between temperature and growth rate. On the other hand, agitation did not benefit from ethanol production or microbial growth. The possibility of noncompetitive inhibition within such a system was deduced from the calculation of the kinetic constants Km and Vmax. Continuous fermentations were carried out at 60°C and pH 7.0 using 1.5 and 3% pure cellulose as a limiting substrate. The maximum ethanol concentration reached during the 1.5% cellulose fermentation was 0.3%. and 0.9% during the 3% cellulose fermentation. The yield of ethanol was about 0.3 grams per gram of consumed cellulose. The overall yield in both schemes was around 0.45 and 0.75 grams per gram of cellulose degraded. It was concluded that cellulose could be degraded continuously in a system with C. thermocellum for production of ethanol. While the continuous system like the batch method is feasible, it may not be promising as yet because of the slow generation time of this microorganism.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 69-82 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Factors affecting the long-term operational stability of a CSTR-hollow-fiber reactor for continuous hydrolysis of proteins were studied. The activity declined in a stepwise manner during a run. Declining from 92% conversion to 60% conversion in about ten hours at a space time of four minutes. Initial decay appears to be due to leakage of small active fragments of the enzyme mixture (Pronase) through the membrane, and later decay due to thermal degradation and loss of activators such as calcium through the membrane. The rate of buildup of unconverted substrate in the reaction vessel was controlled by operational variables, but did not appear to affect the reactor output or the operation of the reactor. The decay of the reactor could be partially compensated for by appropriate manipulation of the space-time variables.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 83-96 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pyrite single-crystal cubes were cut, polished. and x-rayed to produce orientations of (100), (110), (111), and (112). These crystallographically developed surfaces then were prepared to expose an area of 1 cm2, and the remainder of the crystal was coated with an acid-resistant silicone cement. Crystals with representative orientations then were leached in ferric sulfate solutions adjusted to a pH of 2.3 with H2SO4 containing up to 6 × 103 ppm of Fe3+ at 30 and 55°C. Leaching was also conducted in acid-bacterial lixiviants containing Thiobacillus ferrooxidans at 30°C and a thermophilic microorganism at 55°C. Surface corrosion and pitting associated with pyrite leaching were examined by scanning electron microscopy. Pyrite leaching in ferric sulfate solutions was observed to be different when compared to acid-bacterial leaching. Ferric sulfate leaching required nearly 2 × 103 ppm of Fe3+ at 30°C while acid-bacterial leaching at 30°C occurred without additions of Fe3+, and values of Fe3+ never exceeded 102 ppm. Because of precipitate formation, an accurate assessment of the role of crystallographic orientation on the leaching of pyrite is difficult.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 97-107 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Purified antithrombin III (AT III), a single-chain human plasma glycoprotein, molecular weight 58,000 daltons, and one of the major serine protease inhibitors, was heated in the 60-70°C range for inactivating possible contaminations by hepatitis B virus (HBV). Loss of inhibitory activity, unfolding of tertiary structure, and the rate of aggregate formation of AT III were monitored experimentally during heatig. Sucrose and sodium citrate were demonstrated to stabilize the protein. From the rate data the calculated activation energies (E) showed Etert. struct. 〈 Ebiol. act. 〈 Eaggreg. indicating the order (lower activation energy process first) in which heat causes these changes in the protein molecule. The activation energy corresponding to denaturation of HBV was estimated to be at least fourfold lower than that associated with the unfolding of the tertiary structure of the protein. Purified AT III, thus stabilized and pasteurized, should be therapeutically effective, and the risk for transmission of hepatitis B should be decreased significantly.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 109-125 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The biomass yield, cellulolytic activity, and protein recovery using Aspergillus terreus GN1 with alkali-treated sugarcane bagasse was studied using different levels (250-600 mg of N/L of broth) of organic and inorganic nitrogen sources. e.g., cattle urine, urea, cornsteep liquor, ammonium sulfate, ammonium nitrate, ammonium iron sulfate, ammonium chloride, and sodium nitrate. Among different levels of alkali-treated bagasse substrate concentrations (0.5-4.0% w/v) tested, 1.0% substrate yielded the highest crude protein content, protein recovery, and cellulolytic activity. The biomass recovery with 1.0% substrate ranged from 290-380 mg/500 mg bagasse substrate in a 50-mL broth with a nitrogen level of 250-600 mg of N/L in all the sources except ammonium iron sulfate, which yielded 402-439 mg/500 mg bagasse substrate. However, crude protein content of biomass obtained with an ammonium iron sulfate nitrogen source was the lowest. Cornsteep liquor nitrogen source at the rate of 600 mg of N/L yielded the maximum crude protein of 32.9%, protein recovery of 22.2 g/100 g of bagasse, and carboxymethyl cellulase and filter paper enzyme activities of 1.1 and 0.09 units/mL, among the organic and inorganic nitrogen sources studied. In general, the organic nitrogen sources and inorganic nonammonium nitrogen sources were utilized preferentially for protein production over the inorganic ammonium nitrogen sources. The fermentation time required under optimum cultural and nutritional conditions for A. terreus GN1 was also evaluated. The crude protein content of the biomass increased gradually up to the seventh day of fermentation, but the protein recovery rate was high up to two or three days. It was observed that the cellulose utilization rate increased after an initial lag of one day up to the third day and gradually increased further, which corresponded positively with protein content, biomass protein recovery, and cellulase enzyme activity. On the seventh day of fermentation, the crude protein content, biomass protein recovery, water-soluble carbohydrate, bagasse cellulose utilization, CMCase, and FPase activities were 32.8%, 20.1 g/100 g of bagasse, 6.2%, 82.7%, 1.0. and 0.08 U/mL, respectively. The final biomass recovered contained 32.8% crude protein content and had an in vitro rumen digestibility (IVRD) coefficient of 68.8%. The biomass contained almost all the essential and nonessential amino acids and was comparable with FAO reference protein. It is concluded that a fermentation time of 72 h gave a faster rate of protein production of 16.9 g/100 g of bagasse with 69.8% bagasse cellulose utilization with 76.0% IVRD. and contained almost all the essential and nonessential amino acids.
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 153-164 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The application of the radial-flow growth chamber to the study of the initial stages of bacterial adhesion to surfaces under flowing conditions is reported. The adhesive properties of the bacterium Pseudomonas fluorescens (NCIB 9046) to stainless steel (type AISI 316) were found to be highly dependent on surface shear stress and the time and concentration of cells used in the incubation procedure. Maximum levels of adhesion occurred in zones of lowest surface shear stress, particularly less than 6-8 Nm-2. Adhesion was still noticeable at shear stresses even up to 130 Nm-2. Significant detachment of cells from a monolayer attached under static conditions was found to occur at surface shear stresses in excess of 10-12 Nm-2.
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 143-152 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The specific uptake rate Qp of orthophosphate (expressed throughout as phosphorus) and the specific growth rate μ of Microcystis aeruginosa were measured using batch-precultured cells, whose growth phase, and intracellular and extracellular phosphorus concentrations fp and P, respectively, had been changed. When the cells from phosphorus-rich precultures were used, smaller values of Qp (0.1-0.3 μg P mg dry wt. -1 h -1) were observed. However, if phosphorusstarved cells were used, the initial value of Qp was enhanced to more than ten times those smaller values referred to above, but declined rapidly with time after the transfer. Qp leveled off at around t = 4 h, when fp approached the maximum value, even if phosphorus was still available in the medium. A new correlation was presented here with respect to Qp as a function of P and fp as follows: \documentclass{article}\pagestyle{empty}\begin{document}$$ Q_p = Q_{p,\max } \frac{P}{{K_p + P}}\frac{{(f_{p,\max } - f_p )}}{{(f_{p,\max } - f_p )}} $$\end{document} Although numerical values of parameters involved in the equation depend on physiological state (or preculture history) of the cells, the above equation could account not only for phosphorus uptake, during which changes in phosphorus content in the cells were observed, but also for initial rates of uptake presented previously by other workers. μ Values were confirmed to be a hyperbolic function of fp as has been suggested by previous workers.
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 127-141 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Isoelectric soya-protein precipitate densities were measured for mean particle sizes ranging from 3.4-65 μm by gradient centrifugation, centrifugation in water-immiscible solvents, tracerdilution, gravity sedimentation of isolated particles. Coulter counter volume determination, and a comparison of Coulter counter and centrifugal sedimentation size distributions. The immiscible system and tracer dilution methods were both found to be unreliable due to experimental uncertainties. The Coulter counter volume measurement indicated the existence of a density-size relationship with the aggregate density decreasing as the size increased. Comparison with sedimentation measurements showed that the Coulter counter measures 80% of the total aggregate volume for 6-μm particles. The relation between aggregate density (ρa, kg m -3) and size (d, μm) was measured for isoelectric soya protein and casein precipitated by ammonium sulfate, using a comparison of the Coulter counter size distribution and centrifugal sedimentation. The functions were described for soya by \documentclass{article}\pagestyle{empty}\begin{document}$$ \rho _a - 1004 = 246d^{ - 0.408} $$\end{document} and for casein by \documentclass{article}\pagestyle{empty}\begin{document}$$ \rho _a - 1136 = 31d^{ - 0.441} $$\end{document} The gradient centrifugation method measured the buoyant density of hydrated protein precipitate which was independent of size, and is consistent with an aggregate structure consisting of primary particles. However, the aggregate structure was not described for all sizes by the theoretical cubic packing of hard-sphere primary particles, nor by the successive random addition of primary particles. The density-size functions indicated up to a fivefold difference in Stokes settling velocities compared to those calculated assuming a constant density difference.
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  • 14
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 165-175 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A. paraffineus ATCC 19558 grown in MMSM (modified mineral salts medium) containing hydrocarbon produced surfactant, with a maximum CMC-1 value obtained by using hexadecane as the carbon source. No activity of surface active agent in whole broth was observed when glucose was used in the MMSM instead of hexadecane. The biomass concentration obtained with glucose was about 40% of that obtained with hexadecane. Glucose (4%) in the medium contaning hexadecane caused a 27 and 21% decrease of biomass and surfactant concentrations, respectively. In the process of surfactant production, glucose can be used as a carbon source for growth, and hexadecane added later can serve for production of the surface active agent. The optimum temperature for production of surfactant is 27°C.
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  • 15
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 177-191 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An unstructured model is presented to describe growth of mycelial pellets in submerged cultures. This model integrates growth kinetics at the scale of the hyphae with the physical mechanisms of mass-transfer processes at the scale of the pellets and the fermentor. The main elements of the model are biomass, substrate, and oxygen balances for the liquid phase and the pellets. The possible occurrence of oxygen limitation in the pellets is introduced in analogy with catalyst theories by means of an effectiveness factor. To simulate the growth of pellets the model is transferred into a computer program. The model is tested by means of fermentation experiments in a bubble column. Results of the growth experiments compare favorably with the outcome of computer simulations.
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  • 16
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    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 193-205 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Hydrocarbon oils of the alga Botryococcus braunii, extracted from a natural “bloom” of the plant, have been hydrocracked to produce a distillate comprising 67% gasoline fraction, 15% aviation turbine fuel fraction, 15% diesel fuel fraction, and 3% residual oil. The distillate was examined by a number of standard petroleum industry test methods. This preliminary investigation indicates that the oils of B. braunii are suitable as a feedstock material for hydrocracking to transport fuels.
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  • 17
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 207-216 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The performance of a new method of enzyme immobilization based on photochemically initiated direct graft copolymerization was recently investigated. The immobilization reaction can be carried out in a simple way and by carefully selecting the reaction conditions, the enzyme-graft copolymer can be obtained as the main reaction product. Coupling efficiency of glucose oxidase has been found to depend only on the amount of photocatalyst (FeCl3) fixed on Sepharose used as polysaccharide support. Small quantities of glycidymethacrylate (GMA) (0.25 g/g dry Sepharose) are sufficient but necessary to achieve the best enzyme coupling efficiency (20-40%). Enzyme immobilization occurs very rapidly and the entire reaction occurs within 60 min. Reaction patterns and physicochemical characteristics of the obtained enzyme-graft copolymers exclude the glucose oxidase entrapment: therefore a covalent attachment mechanism may be proposed. The kinetic parameters of immobilized glucose oxidase (Km′ = 2.0 × 10-2M) are quite similar to those of free enzyme (Km = 1.93 × 10-2M), and no diffusion limitation phenomena are evidenced in samples having different enzyme or polymer content. Lyophilization, thermostability, and long-term continuous operation also have been investigated. The advantages of this method over that using vinylenzyme copolymerization are discussed.
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  • 18
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 217-236 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pulsing of temperature in a fermentor at intervals coincident with cell generation time was used to induce synchrony in a population of the fission yeast Schizosaccharomyces pombe. Measurements of culture protein, RNA, and DNA during synchronous growth confirm continuous synthesis of protein and RNA and discontinuos synthesis of DNA as previously reported. Flow microfluorometry of populations at different times during the synchrony cycle was used to monitor the changes in single-cell protein. RNA, and DNA frequency functions. These measurements illustrate very clearly the degree of synchrony and patterns of macromolecular synthesis and also confirm previous estimates of the cellular protein contents characteristic of dividing cells. Additional insights into single-cell kinetics and division controls are provided by two-parameter flow microfluorometry measurements and by mathematical modeling of population dynamics. Such data are necessary foundations for robust population balance models of microbial processes.
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  • 19
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    Biotechnology and Bioengineering 24 (1982), S. 237-240 
    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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  • 20
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    Biotechnology and Bioengineering 24 (1982), S. 241-243 
    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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  • 21
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    Biotechnology and Bioengineering 24 (1982), S. 245-249 
    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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  • 22
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    Biotechnology and Bioengineering 24 (1982), S. 251-254 
    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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  • 23
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982) 
    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
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    Biotechnology and Bioengineering 24 (1982), S. 259-280 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Since it has not been possible to produce penicillin in tower-loop reactors with highly viscous filamentous molds of Penicillium chrysogenum which are employed in stirred-tank reactors, a new strategy has been developed to avoid the formation of this morphology and to use the pellet form of the fungi. When employing definite impeller speeds in the subculture in connection with definite inoculum amounts and substrate concentrations in the main culture (bubble column), it is possible to generate a suspension of isolated small pellets, which shows a low broth viscosity up to a sediment content of 45% over the entire fermentation time. Volumetric mass-transfer coefficients kLas are by a factor of 4 to 5 higher in these pellet suspensions than in filamentous broths. It was easy to maintain the necessary oxygen supply for penicillin production in these pellet suspensions. Under these conditions the specific penicillin productivities were higher with regard to power input (up to 90%), biomass, and consumed substrate than in the stirred-tank reactors with highly viscous filamentous morphology of the fungi. Under nonoptimized operating conditions the absolute penicillin production in the tower loop was 35% lower than in the stirred-tank reactor due to lower possible biomass concentrations. The separation of the biomass, and therefore the penicillin recovery, is much simpler when employing pellets. It is shown how the particular mass transfer resistances at the gas/liquid and liquid/pellet interfaces and within the pellets change with the pellet diameter. There should be a particular pellet diameter at which penicillin productivity has its maximum. These investigations indicate that the use of tower-loop reactors can, in the future, be an alternative for more economical penicillin production methods.
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  • 25
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982), S. 281-292 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Emulsan is a polymeric extracellular emulsifying agent produced by Acinetobacter RAG-1. Hydrocarbon-in-water emulsions (Vf of hydrocarbon of 0.01-0.10) were stabilized by small quantities of emulsan (0.02-0.2 mg/mL). Although both aliphatic and aromatic hydrocarbon emulsions were stabilized by emulsan, mixtures containing both aliphatics and aromatics were better substrates for emulsan than the individual hydrocarbon by themselves. The emulsan remained tightly bound to the hydrocarbon even after centrifugation as determined by (a) residual emulsan in the aqueous phase and (b) the fact that the resulting “cream” readily dispersed in water to reform stable emulsions. With hexadecane-to-emulsan weight ratio of 39 and 155, the noncoalescing oil droplets had average droplet diameters of 2.0 and 4.0 μm, respectively. Dialysis studies showed that the water-soluble dye Rhodamine B adsorbed tightly to the interface of hexadecane-emulsan droplets although the dye did not bind to either hexadecane or emulsan alone. At saturating concentrations of dye, 2.2 μmol of dye were bound per mg emulsan.
    Additional Material: 6 Ill.
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  • 26
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    Biotechnology and Bioengineering 24 (1982), S. 293-304 
    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 shown that simultaneous attrition of cellulose in an attritor containing stainlesssteel beads results in a substantial enhancement of the enzymatic hydrolysis. The attrition exerts two opposing effects, continuous delamination and comminution of the substrate with formation of new reactive sites and a gradual denaturation and inactivation of the enzyme. Consequently, the hydrolysis proceeds very rapidly at first and levels off at about 70% saccharification of the substrate. Accumulation of hydrolysis products is also responsible for inhibition of the enzyme. The attrition method is effective for the saccharification of cottonwood in which the cellulosic microfibrils are embedded in a matrix of lignin and hemicelluloses. A comparison between the saccharification of wood, lignocellulose, holocellulose, and cellulose with simultaneous attrition showed that the lignin component provided more hindrance toward the saccharification process than hemicelluloses, which are themselves subject to enzymatic hydrolysis.
    Additional Material: 5 Ill.
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  • 27
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    Biotechnology and Bioengineering 24 (1982), S. 305-315 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Photosynthetic ATP accumulation was shown in the presence of exogenous ADP plus orthophosphate on illumination to the intact cells of a strain of thermophilic blue-green algae isolated from Matsue hot springs, Mastigocladus sp. Kinetic studies of various effectors on the ATP accumulation proved that the ATP synthesis depends mainly on the cyclic photophosphorylation system around photosystem I (PS-I) in the algal cells. The temperature and pH optima for the accumulation were found at 45°C and pH 7.5. Maximum yield was obtained with light intensity higher than 15 mW/cm2. Borate ion exerted pronounced enhancement on the ATP synthesis. With a continuous reactor at a flow rate of 1 ml/hr at 45°C and pH 7.5, efficient photoconversion of ADP (2mM, at substrate reservoir) to ATP (1mM, at product outlet) has been maintained for a period of 2.5 days, though the efficiency has decreased in a further 2-day period to the level of 0.5mM ATP/9.5 h of residence time.
    Additional Material: 7 Ill.
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  • 28
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    Biotechnology and Bioengineering 24 (1982), S. 317-328 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sucrose phosphorylase was immobilized on porous ceramic beads with 3-aminopropyltriethoxysilane and glutaraldehyde. It was determined experimentally that under laboratory conditions there was no diffusional resistance to the enzyme-catalyzed reaction. The half-life of the immobilized enzyme varied from about 35 days at 30°C to about 5 days at 40°C. The pH optimum was found to be between 6.5 and 7.0. The activation energy for the reaction was found to be about 12.5 kcal/mol. Eleven independent kinetic constants in the complete rate equation for the previously proposed ping-pong mechanism were found to be in good agreement with those for the soluble enzyme.
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  • 29
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    Biotechnology and Bioengineering 24 (1982), S. 347-354 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: As the hydrolysis of starch by glucoamylase proceeds with stepwise removal of glucose units from the nonreducing ends of the starch chain, the number of available substrate molecules is essentially unchanged in the course of the degradation. In view of this aspect, a simple practical kinetic expression, which consists of a modified Michaelis-Menten form with product inhibition, is presented for the hydrolysis of soluble starch. It is assumed that the values of kinetic parameters Vm and Km vary linearly from the values for starch toward those for maltose. The applicability of this kinetic expression is verified through the simulation with the experimental results for the hydrolysis of two soluble starches with different average molecular weights of 3 × 104 and 3 × 106.
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  • 30
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A derivative of crosslinked Sepharose, p-(N-acetyl-L-tyrosine azo) benzamidoethyl-CL-Sepharose 4B, was synthesized and used for the selective immobilization of thermostable lactase from Aspergillus oryzae.Preparations of soluble and immobilized lactase were evaluated under initial velocity conditions in a batch process. Immobilization had no significant effect on the pH optimum at 50°C or kinetic parameters at pH 4.5 or pH 6.5 and 50°C. At pH 4.5, the soluble enzyme possessed maximum activity at 60°C and the immobilized at 55°C; at pH 6.5 both showed maximum activity at 55°C. The activation energy, entropy, and enthalpy decreased significantly with immobilization at pH 4.5 but not at pH 6.5. When the immobilized enzyme was placed in a packed-bed reactor, the effect of temperature on activity was altered as reflected by a marked decrease in the thermodynamic parameters of activation at both pH levels. Upon immobilization there was also a dramatic increase in the apparent thermal stability of the lactase, and the mean half-life at 50°C was increased from 7.2 to 13 days at pH 4.5 and from 3.8 to 16 days at pH 6.5.
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  • 31
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    Biotechnology and Bioengineering 24 (1982), S. 355-369 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Glucoamylase and pullulanase were immobilized on reconstituted bovine-hide collagen membranes using the covalent azide linkage method. A pretanning step was incorporated into the immobilization procedure to enable the support matrix to resist proteolytic activity while accommodating an operating temperature of 50°C. The immobilized glucoamylase and pullulanase activities were 0.91 and 0.022 mg dextrose equivalent (DE) min-1 cm-2 of membrane, respectively. Immobilized glucoamylase had a half-life of 50 days while the immobilized pullulanase had a half-life of 7 days. This is a considerably improved stability over that reported by other researchers. The enzymes were studied in their free and immobilized forms on a variety of starch substrates including waxy maize, a material which contains 80% α-1-6-glucosidic linkages. Substrate concentrations ranged from 1% to a typical commercial concentration of 30%. Conversion efficiencies of 90-92% DE were obtained with free and immobilized glucoamylase preparations. Conversion enhancements of 4-5 mg of DE above this level were obtained by the use of pullulanase in its free or immobilized forms. Close examination of free pullulanase stability as a function of pH indicated improved thermal stability at higher pH values. At 50°C and pH 5.0, the free enzyme was inactivated after 24 h. At pH 7.0, the enzyme still possessed one-half its activity after 72 h. Studies were conducted in both batch and continuous total recycle reactors. All experiments were conducted at 50°C. Experiments conducted with coimmobilized enzymes proved quite promising. Levels of conversion equivalent to those obtained with the individually immobilized enzymes were realized.
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  • 32
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    Biotechnology and Bioengineering 24 (1982), S. 371-384 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The yeast Pachysolen tannophilus was found to be capable of converting D-xylose to ethanol. Batch cultures initially containing 50 g/L D-xylose yielded 0.34 g of ethanol per gram of pentose consumed. Aerobic conditions were required for cell growth but not for ethanol production. Both alcohol formation and growth were optimum when incubation temperature was 32°C, when pH was near 2.5, and when D-xylose and ethanol concentrations did not exceed 50 and 20 g/L, respectively.
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  • 33
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    Biotechnology and Bioengineering 24 (1982), S. 385-401 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Biosorption of elements is a little understood phenomenon exhibited by some types of even nonliving microbial biomass. A common fungus Rhizopus arrhizus has been reported to take up uranium from aqueous solutions to the extent of 180 mg U6+/g. The mechanism of uranium sequestering by this type of biomass was studied by using experimental techniques such as electron microscopy, x-ray energy dispersion analysis, IR spectroscopy, and supporting evidence was obtained for a biosorption mechanism consisting of at least three processes. Uranium coordination and adsorption in the cell-wall chitin structure occur simultaneously and rapidly whereas precipitation of uranylhydroxide within the chitin microcrystalline cell-wall structure takes place at a lower rate. Interference of Fe2+ and Zn2+ coions with uranium biosorption is indicated.
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  • 34
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    Biotechnology and Bioengineering 24 (1982), S. 403-423 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method is described for the immobilization on tritylated agarose or Sepharose columns of a wide spectrum of enzymes, including types useful in contemporary biochemistry/molecular biology, many of which have never before been reported as immobilized. The method involves the formation of noncovalent hydrophobic bonds between the enzymes and trityl groups which are attached to the agarose by means of ether bonds. The immobilization of calf intestinal and E. coli alkaline phosphatases to tritylagarose is reported in detail. Their binding strength, binding capacity, and long-term stability (greater than six months) are described as a function of the salt concentration, pH, buffer type, and degree of agarose substitution. Homologies are noted between tritylagarose-bound and membrane-bound phosphatases. This method compares favorably with other methods, covalent or otherwise, reported to date, in terms of the enzyme immobilization yield (ca. 100%), the mildness of conditions, resulting, in most cases, in the retention of a high degree of activity, the ease and speed of the manipulations, and the long-term stability of the immobilized enzyme. Further, it is noted that highly tritylated and crosslinked Sephadex G10 selectively and mildly removes detergents from enzyme solutions.
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  • 35
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    Biotechnology and Bioengineering 24 (1982), S. 483-486 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 36
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    Biotechnology and Bioengineering 24 (1982), S. 425-442 
    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 properties of the culture broths of some plant cells (Cudrania tricuspidata, Vinca rosea, and Agrostemma githago) at high density (10-18 g dry wt/L) were measured, and oxygen transfer in the broths in various bioreactors was investigated. The rheological properties of the broths were dependent on the size, specific gravity, and concentration of the cell aggregates contained in the broths. The broths were non-Newtonian and pseudoplastic fluids. The flow behavior index n was fairly constant (0.53) and the consistency index K varied in proportion to the sixth-to-seventh power of the cell mass concentration M. The apparent viscosity μa of the broths was in proportion to the 6.5th power of M. The oxygen transfer in the broths was discussed on the basis of the results obtained for suspensions of granulated agars (agar concentration, 5.8%) in water, which were similar to the broths in rheological properties. The volumetric oxygen transfer coefficient kLa in the broths was dependent on μa(kLa ∝ μa-m) and decreased greatly at a certain apparent viscosity, μac. The values of m and μac were closely related to the aeration-agitation mechanisms of the bioreactors. The values of μac in aeration-agitation type bioreactors was larger than that in aeration-type bioreactors, whereas for m, the reverse was true.
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  • 37
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    Biotechnology and Bioengineering 24 (1982), S. 461-481 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Differing findings on the volumetric mass transfer coefficients kLa in CMC solutions in bubble column bioreactors have been reported in the literature. Therefore, oxygen mass transfer was studied again in CMC solutions in a 14-cm-i.d. × 270-cm-height bubble column using different spargers. The kLa values were determined along with the dispersion coefficients by fitting the prediction of the axial dispersed plug model with the experimental oxygen concentration profiles in the liquid phase. Surprisingly, the obtained liquid phase dispersion coefficients for CMC solution are higher than one would expect from correlations. The kLa data depend largely on the flow regime. In general, they are lower than those reported in the literature. The data for developing slug and established slug flow are dependent on the gas velocity and the effective viscosity of the solution and can br correlated by a simple correlation. This correlation describes kLa values measured on fermentation broth of Penicillium chrysogenum with striking agreement.
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  • 38
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    Biotechnology and Bioengineering 24 (1982), S. 443-459 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Residence-time-distribution experiments for the fluid in a 30-m3 pilot plant and a 200-m3 prototype upflow reactor were performed by means of continuous injection of an LiCl solution as a tracer in the influent of the reactor and measurement of the response of this stimulus on several location in the reactor and in the effluent. In a similar way as described in an article published earlier, models have been developed by use of the measured data of the fluid flow pattern which consisted of region of ideal mixing, plug flow, dead space, and short circuiting. It appeared that the fluid flow patterns in the two reactors were to a large extent analogous. For the pilot plant, three-mixer models appeared to be appropriate while for the prototype reactor two-mixer models have been found. This differences was a result of the difference in the heights of the sludge beds in the reactors: 2-3 m in the pilot plant and only 0.4 m in the prototype reactor, a result of too small an amount of sludge. Another differences was that, due to large amount of mud in the prototype reactor, a region of dead space occurred in the models for the fluid flow pattern in this reactor. The dimension of the prototype reactor have been chosen according to several recommendations obtained from work with the pilot plant (e.g., scale-up should be done by increasing the cross section of the reactor; one influent point should be applied per 5 m2 bottom surface). The results presented here clearly show the value of these recommendations.
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  • 39
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    Biotechnology and Bioengineering 24 (1982), S. 495-500 
    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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  • 40
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    Biotechnology and Bioengineering 24 (1982), S. 487-493 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 41
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    Biotechnology and Bioengineering 24 (1982), S. 501-506 
    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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  • 42
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    Biotechnology and Bioengineering 24 (1982), S. 507-509 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: No abstract.
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  • 43
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    Biotechnology and Bioengineering 24 (1982) 
    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 24 (1982), S. 533-552 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: During drying of food materials a multitude of chemical reactions and/or physical changes may occur. In this article attention is focused on one of these, namely, inactivation of enzymes during drying. The prediction of enzyme retention during drying is of interest to the pharmaceutical industry for the production of dry enzyme preparations and to the food processing industry in drying operations of food materials containing enzymes. In this article calculated enzyme retentions are presented for different drying histories and shapes of drying particles. In the numerical calculations it is assumed that enzyme degradation kinetics are first-order reactions, of which reaction constants are known as a function of temperature and water concentration in the drying material. From the calculations, conclusions can be drawn about conditions favorable for high enzyme retentions, or for high enzyme degradations.
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  • 45
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    Biotechnology and Bioengineering 24 (1982), S. 511-531 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Until recently, the recycle of the solid (microbial), liquid, or gaseous phases in microbiological processes has only been practiced rarely, with the notable exception of activated sludge processes for wastewater treatment, where recycling of a large fraction of the microbial phase is essential for process stability and performance. During the last decade, the economic impact of a number of politically motivated changes with respect to energy and feedstock costs and availability, and legislation directed towards markedly higher levels of environmental protection have encouraged the evaluation and subsequent development of recycle technology in the fermentation industry. Many of the developments have occurred in isolation and some have failed to result in either an improvement in process economics or any reduction in the quantity of pollutants discharged. This article seeks to review the present diversity of approaches to recycle technology in fermentation processes in order to provide a sensible basis for future developments.
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  • 46
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    Biotechnology and Bioengineering 24 (1982), S. 553-578 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new experimental method has been developed for estimating the hydrodynamic stress capacity of microorganisms. In a test apparatus, stable continuous cultures of three types of green algae and two cyanobacteria were exposed to well-defined hydrodynamic loads in a free jet. During and after the stress experiments the cultures showed a different response due to the damage in the jet. The results of these free-jet experiments with short stress exposure were compared to those of stirring experiments in which hydrodynamic load was continuously generated by a stirrer. In both kinds of experiments distinct critical stress values could be determined below which no essential damage of the microorganisms cultures occurred. A correlation between the critical stress values in free-jet and stirring experiments was found. It can be deduced that the free-jet data, expressed as critical volumetric dissipated energy, are suitable for the calculation of hydrodynamic stress to which microorganisms might be exposed in biotechnical plants without suffering damage.
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  • 47
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    Biotechnology and Bioengineering 24 (1982), S. 579-594 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Theoretical considerations confirmed by outdoor experiments indicated carbon limitation of biomass production in high-rate oxidation ponds at certain seasonal and operational conditions. Apparently, free carbon dioxide concentration in the pond is the major determinant of carbonlimiting algal photosynthesis. High concentrations of free CO2 are provided through bacterial respiration which is the main contributor to algal photosynthesis. At high photosynthetic activities and low organic loadings, free CO2 concentrations are low; its flux into algal cells determines photosynthesis and biomass production rate in the pond.
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  • 48
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    Biotechnology and Bioengineering 24 (1982), S. 595-604 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Ethanol-producing bioreactors employing cells of Zymomonas mobilis attached to glass-fiber pads were operated continuously for as long as 28 days. Ethanol production, which is related to bed-associated biomass levels, was found to occur in three distinct phases: an exponential phase, a linear phase, and a “steady-state” phase. After prolonged operation, a bacterial floc developed in the reactor. The maximum effluent ethanol concentration and the maximum volumetric productivity were 6.4% and 152 g L-1 h-1, respectively, and both were attained at a liquid residence time of from 10-15 min. Both maxima occurred after the development of the bacterial floc. The flocculant bacterium has been isolated and tentatively identified as a flocculant strain of Z. mobilis.
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  • 49
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    Biotechnology and Bioengineering 24 (1982), S. 605-617 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The immobilization of living Acetobacter cells by adsorption onto a large-surface-area ceramic support was studied in a pulsed flow reactor. The high oxygen transfer capability of the reactor enabled acetic acid production rates up to 10.4 g L-1 h-1 to be achieved. Using a simple mathematical model incorporating both internal and external mass transfer coefficients, it was shown that oxygen transfer in the microbial film controls the reactor productivity.
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  • 50
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    Biotechnology and Bioengineering 24 (1982), S. 619-631 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The freshwater alga Scenedesmus obliquus was grown in continuous culture at a fixed dilution rate of 0.5/day, but at varying pH in the range 4.17-10.67. The pH was regulated in the range 4.17-7.67 by continuously bubbling 1% CO2-enriched air into the cultures and by varying the source of nitrogen (NO3-, NH4+, or urea) in the growth medium, which, in turn, led to changes in culture alkalinity. Culture alkalinity and PCO2 were the sole determinants of pH. A pH-stat system, together with NO3- in the medium, was used to regulate the pH in the range 7.92-10.67. Maximum productivity, which occurred at pH 6.6, was dependent on N source only to the extent that culture alkalinity was a function of nitrogen uptake. The results demonstrate that the choice of N is a critical factor in controlling the pH of large-scale algal cultures. NH4+ is a poor source of N because it leads to destruction of culture alkalinity and concomitant growth-inhibiting reductions in pH, whereas NO3- has an opposite effect, although pH is not so severely affected in this case. Urea is, by far, the most suitable N source for maximizing algal yield when it is supplied in combination with the proper amounts of HCO3- alkalinity in the growth medium and percent CO2 in the bubbled gas that will lead to an equilibrium pH near the optimum pH.
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  • 51
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    Biotechnology and Bioengineering 24 (1982), S. 633-649 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This work is concerned with statistical methods to estimate yield and maintenance parameters associated with microbial growth. For a given dilution rate, an experimenter typically measures substrate concentration, oxygen utilization rate, the rate of carbon dioxide evolution, and biomass concentration. These correlated response variables each contain information about the maintenance and yield parameters of interest. A maximum likelihood estimator which combines this correlated information for the yield and maintenance parameters is proposed, evaluated, and tested on literature data. Both point and interval estimators are considered.
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  • 52
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    Biotechnology and Bioengineering 24 (1982), S. 651-668 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Several combinations of backmix, tubular-loop, and plug-flow fermentors with and without culture recycle were studied by computer simulations. The steady-state concentrations of cell mass in a continuous culture were calculated as a function of dilution rate using Monod growth kinetics. It was found theoretically and verified for one case experimentally that the maximum dilution rate, over which microbial cells were washed out from the fermentor, could be elevated well beyond the maximum specific growth rate if a particular fermentor combination was used. A combination of two backmix fermentors has been analyzed previously by Sinclair and Brown. Application of this type of fermentor combination as a seed tank for performing continuous culture of microbes in a plug-flow reactor was shown with special reference to fermentation production using the kinetics proposed by Luedeking and Piret, van Dedem and Moo-Young, and Brown and Vass.
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  • 53
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    Biotechnology and Bioengineering 24 (1982), S. 669-689 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The reaction rates (rNH4+ and rNO2-) in the two-step nitrification reaction were measured in a fluidized-sand-bed biofilm reactor under a range of steady-state conditions with respect to bulk NH4+, NO2-, and O2 concentrations. It was shown from theory and experiment that under low NH4+ concentration conditions, if the O2/NH4+ concentration ratio in the bulk liquid is less than the stoichiometric coefficient (3.4 mg/mg), then oxygen will be rate limiting. In all experiments rNO2- decreased more than rNH4+ under low oxygen conditions. This resulted in high NO2- effluent concentrations under low residence time conditions. The influence of the oxygen penetration effects on the relative values of rNH4+ and rNO2- was experimentally shown to be caused either by the Nitrobacter location in the inner biofilm regions or by a Km effect for oxygen. Theoretical support of these findings was provided by a differential diffusion-reaction model which was used to simulate the experimental results.
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  • 54
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    Biotechnology and Bioengineering 24 (1982), S. 703-723 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effective enzyme activity decay can be decreased by diffusion limitation in the immobilized pellet. Thiele modulus changes and/or poisoning of various enzyme forms are two phenomena which are influenced by diffusion limitation. This article considers these effects on enzyme decay as applied to glucose isomerase.
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  • 55
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    Biotechnology and Bioengineering 24 (1982), S. 691-701 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The optimum operating conditions for growth and ethanol production of Zymomonas anaerobia ATCC 29501 were established. The optimum pH range and temperature were found to be 5.0-6.0 and 35°C, respectively. Based on the results obtained from the temperature optimization study, an Arrhenius-type temperature relationship for the specific growth rate was developed. The growth and ethanol production of this microbe also have been optimized in terms of concentrations of glucose, essential nutrients, and minerals. With optimum medium and operating conditions, an ethanol concentration of 96 g/L was obtained in 23 h. Both growth and ethanol yield coefficients in dependence on initial glucose concentrations were determined.
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  • 56
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    Biotechnology and Bioengineering 24 (1982), S. 725-730 
    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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  • 57
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    Biotechnology and Bioengineering 24 (1982), S. 731-736 
    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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  • 58
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    Biotechnology and Bioengineering 24 (1982), S. 737-742 
    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 24 (1982), S. 743-748 
    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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  • 60
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    Biotechnology and Bioengineering 24 (1982), S. 749-752 
    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 24 (1982), S. 757-759 
    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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  • 62
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    Biotechnology and Bioengineering 24 (1982), S. 753-756 
    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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  • 63
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    Biotechnology and Bioengineering 24 (1982) 
    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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  • 64
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    Biotechnology and Bioengineering 24 (1982), S. 763-780 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A number of studies on packed-bed immobilized enzyme reactors have shown the significant influence of the external film mass transfer resistance on the apparent kinetic parameters. Some of the earlier mathematical models using approximation techniques have attempted to explain the linearity of the S0x vs ln (1 - x) plots observed experimentally for systems obeying Michaelis-Menten kinetics. However, there has been no critical examination of the bounds of validity of the approximations used. Further, the situations where the above linearity is not valid have been examined neither conceptually nor quantitatively. The work presented here overcomes these drawbacks of the earlier analyses by approaching the problem from a different angle. Methods of evaluation of the intrinsic kinetic parameters under different experimental situations have been outlined and illustrated with several examples.
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  • 65
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    Biotechnology and Bioengineering 24 (1982), S. 797-804 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Recently, considerable interest has been shown in the study and analysis of immobilized cell reactors. One of the major uses of such a reactor system is expected to be in ethanol production from carbohydrates. One distinct disadvantage of this system is carbon dioxide gas holdup associated with unsteady-state temperature distribution across the reactor. Taking into account the earlier published data and assuming steady-state-substrate balance, and unsteady-state energy balance, and an average gas holdup of 20% with the heat retained by the gas neglected, the average reaction rate in the differential element was computed. Finally, a mathematical model to predict steady-state temperature profile along the reactor was developed. It was verified with experimental data obtained from an immobilized yeast reactor column (1 m × 14.5 cm). The experimental data fit well those computed from the model within an accuracy of 5%.
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  • 66
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    Biotechnology and Bioengineering 24 (1982), S. 781-795 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Rapid fermentation of cane molasses into ethanol has been studied in batch, continuous (free-cell and cell-immobilized systems) by a strain of Saccharomyces cerevisiae at temperature 30°C and pH 5.0. The maximum productivity of ethanol obtained in immobilized system was 28.6 g L-1 h-1. The cells were immobilized by natural mode on a carrier of natural origin and retention of 0.132 g cells/g carrier was achieved. The immobilized-cell column was operated continuously at steady state over a period of 35 days. Based on the parameter data monitored from the system, mathematical analysis has been made and rate equations proposed, and the values of specific productivity of ethanol and specific growth rate for immobilized cells computed. It has been established that immobilized cells exhibit higher specific rate of ethanol formation compared to free cells but the specific growth rate appears to be comparatively low. The yield of ethanol in the immobilized-cell system is also higher than in the free-cell system.
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  • 67
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    Biotechnology and Bioengineering 24 (1982), S. 805-815 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In earlier communications general analyses of rapid ethanol fermentation by Saccharomyces cerevisiae immobilized on inert supports were described. In this article physiology of growth and metabolism (parameters like rates of CO2 evolution and O2 uptake, respiratory quotient, and generation time) of Saccharomyces cerevisiae immobilized on different supports are reported. Values of the ratio of specific oxygen uptake rate for immobilized cells to free cells have been found to be 0.732, 0.781 and 0.785 for carrier A, carrier B, and covalently crosslinked controlled pore glass (CPG, specific surface area of 439 m2 g-1), respectively. Rates of specific CO2 evolution for immobilized cells to free cells for these supports are 0.784, 0.822, and 0.783, respectively. Marked reduction in generation time of Saccharomyces cerevisiae on all the supports has been observed. No change in size (4.8-5 μm) and specific growth rate (μm = 0.275 h-1) of cells leaving the reactor has been observed.
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  • 68
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    Biotechnology and Bioengineering 24 (1982), S. 817-835 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A distributed parameter model for simulation of SCP-production processes in tower reactors with an outer loop was developed by considering substrate, cell, and CO2 balances in the liquid phase, and O2 and CO3 balances in the ges phase and taking into account variations of dissolved oxygen concentration, pressure, and kLa along the column, as well as double substrate Monod kinetics. This model was used to describe the cultivation of Hansenula polymorpha in a tower-loop reactor (height 275 cm, diameter 15 cm). Parameter identification and process simulation were carried out by a hybrid computer. The variation of identified mass transfer parameters with fermentation time and operation mode is considered employing ethanol and glucose substrate, respectively. Relationships among kLa, substrate concentration, and superficial gas velocity were developed to facilitate the layout and simulation of pilot-plant reactors.
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  • 69
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    Biotechnology and Bioengineering 24 (1982), S. 847-856 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The accuracy of kinetic and stoichiometric data obtained from most laboratory-scale continuous-culture equipment, particularly involving gaseous measurements, may be much lower than many workers realize, despite the use of good quality instruments. For example, errors in specific oxygen uptake measurements (QO2) easily can be as high as ±100%. This article assesses the accuracies of individual instruments and of the overall system in greater detail than has previously been reported and suggestions are made as to how the errors can be reduced to acceptable levels.
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  • 70
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    Biotechnology and Bioengineering 24 (1982), S. 837-845 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Alcohol dehydrogenase has been immobilized to the basic copolymer and its several derivatives using various techniques. Enzyme coupling to the supports with amino groups by means of glutaraldehyde was found the most suitable. Activity of alcohol dehydrogenase coupled to these amino supports was comparable to that of the enzyme bound to Sepharose. Thermal and pH stability of alcohol dehydrogenase increased essentially upon immobilization. Kinetic properties of the immobilized enzyme differed from those of free alcohol dehydrogenase, pH optimum shifted to alkaline range, and apparent Michaelis constants for substrates and coenzymes increased. Curvatures observed in Lineweaver-Burk plots for coenzymes suggest an involvement of diffusion effects in the reaction catalyzed by alcohol dehydrogenase linked to these polymers.
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  • 71
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    Biotechnology and Bioengineering 24 (1982), S. 871-887 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The acid precipitation of soya protein was studied in a continuous-flow tubular reactor under conditions of turbulent flow. Preliminary batchwise experiments of a semiquantitative nature were also carried out on a bench-scale reactor to better define the parameters affecting precipitate growth. The experiments indicated the dominant growth mechanism to be the aggregation of primary precipitate particles produced by the contacting of the protein and acid streams. The rate of particle growth was observed to rise with an increase in the protein concentration as well as with greater intensity of turbulence. The final mean particle size decreased with increased intensity of turbulence. A theoretical model was set up to simulate the growth of the precipitate particles.
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  • 72
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    Biotechnology and Bioengineering 24 (1982), S. 857-869 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: By the radiation-copolymerization method with polyethylene glycoldimethacrylate (PGD) as a main polymerizable reagent, microbial cells of Brevibacterium ammoniagenes were immobilized with high specific activity of NAD kinase and high mechanical strength. The reagents used for the immobilization such as PGD, polyvinyl alcohol (PVA), and N,N′-methylenebisacrylamide (Bis) did not inversely affect the enzyme activity. Freezing and irradiation treatment of the cell-reagent solution did not inactivate the enzyme either, but longer freezing time or a lower irradiation dose (less than 400 krad) resulted in the unsatisfactory mechanical strength of the immobilized cells. Almost all of NAD and ATP consumed were converted into NADP within three hours reaction time. The drum reactor was found to be ideal for the reaction of immobilized cells, since it gave little mechanical stress to the immobilized cells for the effective mixing of the cells and the substrates. The immobilized cells were subjected to three hours reaction repeatedly for 30 times without any activity loss.
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  • 73
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    Biotechnology and Bioengineering 24 (1982), S. 889-902 
    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 iron pyrite by Thiobacillus ferrooxidans was studied in a continuous stirred tank reactor at a variety of dilution rates (0.012-0.22 h-1), pyrite surface areas (18-194 m2/L), and inlet soluble substrate (Fe2+) concentrations (0-3000 ppm). The bacterial leaching rate was found to increase with increasing pyrite surface area, dilution rate, and inlet Fe2+ concentration. The concentration of bacteria in solution was related to the concentration of bacteria attached to the pyrite surface by a Langmuir-type adsorption-desorption relation. Fitting the experimental data to this relation yielded a value for the area occupied per bacterium of 86 μm2. This result is consistent with the concept of preferential bacterial attachment of certain sites on the solid. A bacterial growth model was developed that included both bacterial growth in solution and growth of bacteria attached to the pyrite surface. The specific growth rate of the attached bacteria was calculated from this model and was found to increase with increasing solid dilution rate and to decrease with increasing pyrite surface area and soluble substance concentration. An explanation of these results based on an active-inactive site mechanisms was also developed.
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  • 74
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    Biotechnology and Bioengineering 24 (1982), S. 903-918 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Wood chips from bigtooth aspen (Populus grandidentata Michx.) were saccharified by reaction with liquid hydrogen fluoride either anhydrous or containing up to 10% v/v water. The reaction products were separated into a solid lignin fraction and a water-soluble saccharide fraction. The fluoride content of the lignin (determined after alkaline fusion) was initially about 1 mg/g wood, but was lowered to 0.1 mg/g wood by grinding and washing. Thus little or no chemical binding of fluoride to lignin occurred during hydrogen fluoride (HF) solvolysis. Analysis of the water-soluble fraction by gel filtration on Biogel P2 columns showed a range of low-molecular-weight oligosaccharides and only 10-20% sugar monomers. Thus considerable reversion occurred during HF evacuation. Posthydrolysis conditions were optimized for these reversion products by varying temperature and acid concentration. Optimal conditions at 1 h were 140°C with 100mN sulfuric acid or 225mN Hydrofluoric acid resulting in monomer yields of 〉 90% for 0.5% sugar solutions and 〉 80% for 10% sugar solutions. After reaction of pure cellulose (Filter paper) with hydrogen fluoride in the absence of water, and terminating the reaction with calcium carbonate, the reaction intermediate α-D-glucopyranosylfluoride was isolated with a maximal yield of 0.2 g/g paper. Upon purification via paper chromatography glucosylfluoride was identified by its specific rotation and also by gas chromatography-mass spectrometry of its tetra-O-trimethylsilyl derivative.
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  • 75
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    Biotechnology and Bioengineering 24 (1982), S. 955-969 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Inactive cells of Rhizopus arrhizus have been documented to exhibit a high thorium biosorptive uptake (170 mg/g) from aqueous solutions. The mechanism of thorium sequestering by this biomass type was investigated following the same method as for the uranium biosorption mechanism. The thorium sequestering mechanism appeared somewhat different from that of uranium. Experimental evidence is presented which indicates that, at optimum biosorption pH (4), thorium coordinates with the nitrogen of the chitin cell wall network and, in addition, more thorium is absorbed by the external section of the fungal cell wall. At pH 2 the overall thorium uptake is reduced. The kinetic study of thorium biosorption revealed a very rapid rate of uptake. Unlike uranium at optimum solution pH, Fe2+ and Zn2+ did not interfere significantly with the thorium biosorptive uptake capacity of R. arrhizus.
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  • 76
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    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A systematic, kinetic study and comparison of the leaching of mixed metal sulfides by galvanic conversion and in the presence of bacteria has been carried out for the first time using both powder (-100 to -400 mesh) and larger (bulk) specimen systems. The rates of dissolution of copper from chalcopyrite and zinc from sphalerite as single, electrically isolated (separate) systems were compared with electrically contacting (galvanically coupled) systems involving CuFeS2/FeS2 and ZnS/FeS2, with and without bacteria and at temperatures of 30 and 55°C. The dissolution of Cu was observed to increase by a factor of 4.6 when the galvanic leaching of CuFeS2/FeS2 was compared to CuFeS2 leaching at 30°C. When bacteria were present, Cu dissolution increased by an additional factor of 2.1 in the CuFeS2/FeS2 system. At 55°C, the corresponding ratios for Cu were 4.3 and 2.7, respectively. The galvanic leaching of Zn in the ZnS/FeS2 system compared to ZnS leaching increased by a factor of 2 at 30°C; in the presence of bacteria the dissolution of Zn from the ZnS/FeS2 system increased by an additional factor of 1.3 at the same temperature. By comparison, the ratio of Cu dissolution from CuFeS2 in acid-bacterial medium and sterile controls (without bacteria) was 5.5. The corresponding ratio for Zn from ZnS was 2.2 at both 30 and 55°C. The order of reaction was found to be essentially first order for the leaching of powder systems at both 30 and 55°C (with T. Ferrooxidans and thermophilic microorganisms, respectively). The corresponding reaction rate constants were observed to be 12.6 and 22.9 for T. ferrooxidans and the thermophilic microorganisms, respectively. Activation energies for the various systems were also determined.
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  • 77
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    Biotechnology and Bioengineering 24 (1982), S. 971-975 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Glycerol dehydrogenase was immobilized in polyacrylamide gel layered over a small platinum screen and used to catalyze the oxidation of glycerol. In the presence of NAD+ and potassium ferricyanide, the coupling reaction generated a measurable electrical potential which was found to be Nernstian with respect to the glycerol concentration range of 10-4M to 10-1M. The reproducibility of the measurement and the optimal conditions for glycerol determination were described.
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  • 78
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    Biotechnology and Bioengineering 24 (1982), S. 941-953 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article examines the potential of Jerusalem artichoke as a source for ethanol and single-cell protein SCP. In addition, experimental results are presented on batch fermentation kinetics employing two strains of Kluyveromyces marxianus and one strain of Saccharomyces rosei grown on the extract derived from the tubers of Jerusalem artichoke. Of the three cultures examined, Kluyveromyces marxianus UCD (FST) 55-82 was found to be the best producer of ethanol grown in a simple medium at 35°C. The ethanol production was found to be growth-associated having a μmax = 0.41. h-1 and the ethanol and biomass yields were determined to be Yp/s = 0.45 (88% of the theoretical) and Yx/s = 0.04 with 92% of the original sugars utilized. On the basis of carbohydrate yields of Jerusalem artichoke reported in the literature and these batch kinetic studies with K. maxxianus, the calculated ethanol yields were found to range from 1400 kg ethanol acre -1 yr-1to a maximum of 2700 kg ethanol acre -1 yr-1. The SCP yields for K. marxianus were calculated to range between 130 to 250 kg dry wt cell acre -1 yr-1. The potential for developing an integrated process to produce ethanol and SCP is also discussed.
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    Biotechnology and Bioengineering 24 (1982), S. 979-980 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Biotechnology and Bioengineering 24 (1982), S. 981-982 
    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 24 (1982), S. 983-989 
    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 24 (1982), S. 991-997 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 8 Ill.
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  • 84
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    Biotechnology and Bioengineering 24 (1982), S. 999-1006 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
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  • 85
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    Biotechnology and Bioengineering 24 (1982), S. 1007-1013 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 86
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 24 (1982) 
    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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  • 87
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    Biotechnology and Bioengineering 24 (1982), S. 1047-1067 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The changes in the cellulose structure by compression milling were studied and expressed in terms of crystallinity, accessibility, specific surface area, and degree of polymerization. The kinetic parameters, maximum reaction rate, and Michaelis constant were determined experimentally. Based on the experimental results a two-phase model, which is based on the degradation of cellulose by simultaneous actions of the cellulase complex on the crystalline and amorphous phases, is proposed. The relationships between cellulose accessibility and the kinetic parameters were compared with those predicted by the model. A good agreement was found, although the two-phase hypothesis is a simplification of the true state of order in cellulose.
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  • 88
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    Biotechnology and Bioengineering 24 (1982), S. 1015-1045 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A detailed study of the influence of crude dextran on enzyme extractions in aqueous phase systems is presented in this article. The physical parameters of crude dextran, a purified T-500 fraction from Pharmacia, and a hydrolyzed crude dextran are compared and their influence on the phase system parameters investigated. Initially there is a drastic increase in the viscosity of the lower dextran-rich phase and a significant shift in the macroscopic structure of these phases, observed as the “gel-forming” properties of the dextran phases. The latter can be important for the partition of any enzyme by influencing the effect of phosphate concentration on the partition of proteins, although these experiments show that the partition coefficient of several enzymes is not much altered. The partition parameters allow the substitution of Dextran T-500 fractions by crude dextran or unfractionated, slightly hydrolyzed fractions. Using crude dextrans the performance and technical realization of enzyme extraction processes are demonstrated for pullulanase from Klebsiella pneumoniae and formate dehydrogenase from Candida boidinii.Both enzymes were recovered in comparable high yields. The equipment performance was quite good, as indicated by the high throughput values of the separators employed. Especially when using nozzle separators for phase separation there is a better performance in comparison to the Dextran T-500 fraction. No serious technical problems were encountered when replacing the expensive fractionated dextran with a crude dextran. In this way aqueous two-phase systems containing dextran become more feasible for enzyme purification from an economic point of view. The price of about 1.30 German marks (DM) per liter for a useful phase system already appears acceptable for the production of valuable intracellular enzymes.
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  • 89
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    Biotechnology and Bioengineering 24 (1982), S. 1081-1091 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Polymer ampholites, partially N-succinylated chitosans (PSC), and partially N-succinylated glycolchitosans (PSGC) were prepared from chitosan (an N-deacetylated chitin) and glycolchitosan (a partially O-2-hydroxyethylated chitosan), and they were utilized as novel supports for the immobilization of enzymes. The immobilization was conducted simultaneously with gelation of PSC and PSGC by reaction with water-soluble carbodiimide in the presence of enzymes. Enzymes were covalently bonded on PSC and PSGC chains. Maximum activity yields of glucoamylase, β-fructosidase, and D-glucose isomerase were 58.8, 64.3, and 65.2%, respectively. Favorable activity yields of glucoamylase and β-fructosidase were attained with PSC and PSGC having high degree of N-succinylation, but those of D-glucose isomerase were not affected by the degree of N-succinylation (DS). The activity of immobilized glucoamylase was retained up to 85.5% over 30 batch reactions.
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  • 90
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two methods employing a water-soluble carbodiimide for carboxyl activation were investigated for the immobilization of biochemicals to succinamidopropyl-porous glass beads. Immobilization using the simultaneous method (simultaneous addition of carbodiimide and nucleophilic ligand to the beads) and large excess of carbodiimide and a small nucleophile should result in covalent binding to all accessible carboxyl groups. Results obtained with glycine methyl ester indicated that 40% of the total surface carboxyl groups were sterically accessible. Using these reaction conditions with the protein, chymotrypsinogen, suggests that a surface monolayer is immobilized. although far fewer sites are required assuming single point attachment. For ligands containing carboxyl groups and several nucleophilic groups (e. g., enzymes), however, biological inactivation may occur using the simultaneous method. Consequently, a sequential method (activation of the surface with carbodiimide followed by washing and addition of the biochemical to be immobilized) was optimized. Using optimal conditions (20 min activation time at pH 4.75 and room temperature; 2 min wash at pH 7 and 0°C) and 0.1M carbodiimide, nearly half of the accessible surface sites remained in the O-acylisourea form and reacted with glycine methyl ester upon its addition. The amount of surface loading as a function of activation time was consistent with a model constructed using rate constants for O-acylisourea formation and hydrolysis previously derived from solution studies with acetic acid [Swaisgood and Natake, J. Biochem 74, 77 (1973)]. Measurement of reaction rates with glycine methyl ester following surface activation suggests that the rate of reaction with amino groups is at least eightfold greater than the hydrolysis rate. Either immobilization procedure gave comparable enzyme loading and specific activities for the case of sulfhydryl oxidase.
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  • 91
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    Biotechnology and Bioengineering 24 (1982), S. 1093-1103 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The metabolic regulation of tylosin synthesis by Streptomyces fradiae NRRL 2702 was studied in batch and chemostat cultures using a soluble synthetic medium. In batch culture a medium which diminished the trophophase-idiophase kinetic pattern was used to assess the activities of the enzymes involved in tylosin synthesis. The enzymes methylmalonyl-coenzyme A carboxyltransferase (EC 2.1.3.1) and propionyl-coenzyme A carboxylase (EC 6.4.1.3) showed early enzymatic derepression, both enzymes reaching their highest specific activities after 72-96 fermentation. The activity of macrocin 3′ -O-methyltransferase, the enzyme catalyzing the conversion of macrocin (tylosin C) to tylosin (tylosin A). also peaked at 72 h. The specific activities of the three enzymes showed close correlation with the qtylosin value. In chemostat cultures the activities of the enzymes and the intracellular level of the adenylate pool and energy charge were studied as a function of dilution rate. Under steady-state conditions, increases in the specific growth rate repressed the enzymes activities with a concomitant increase in the intracellular level of the adenylate pool, while the adenylate energy charge remained almost constant and in the range 0.5-0.52. The highest specific activities of the enzymes were observed when D = 0.008 h -1. The specific rate of tylosin synthesis was inversely proportional to the specific growth rate and the intracellular level of adenylate pool. The pool of adenylate could be a nutritional parameter which had a considerable influence on the biosynthesis of tylosin.
    Additional Material: 8 Ill.
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  • 92
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The information presented in this publication represents current research findings on the production of glucose and xylose from straw and subsequent direct fermentation of both sugars to ethanol. Agricultural straw was subjected to thermal or alkali pulping prior to enzymatic saccharification. When wheat straw (WS) was treated at 170°C for 30-60 min at a water-to-solids ratio of 7:1, the yield of cellulosic pulp was 70-82%. A sodium hydroxide extration yielded a 60% cellulosic pulp and a hemicellulosic fraction available for fermentation to ethanol. The cellulosic pulps were subjected to cellulase hydrolysis at 55°C for production of sugars to support a 6-C fermentation. Hemicellulose was recovered from the liquor filtrates by acid/alcohol precipitation followed by acid hydrolysis to xylose for fermentation. Subsequent experiments have involved the fermentation of cellulosic and hemicelluosic hydrolysates to ethanol. Apparently these fermentations were inhibited by substances introduced by thermal and alkali treatment of the straws, because ethanol efficiencies of only 40-60% were achieved. Xylose from hydrolysis of wheat straw pentosans supported an ethanol fermentation by Pachysolen tannophilus strain NRRL 2460. This unusual yeast is capable of producing ethanol from both glucose and xylose. Ethanol yields were not maximal due to deleterious substances in the WS hydrolysates.
    Additional Material: 6 Ill.
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  • 93
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    Biotechnology and Bioengineering 24 (1982), S. 1115-1123 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Microbes capable of degrading organic wastes (sewage) are densely packed (immobilized) within the pores of controlled-pore ceramics. When the ceramic displays the optimum pore range for the reproduction of these microbes, the minimum volume for a very efficient reactor is required. A two-stage, anaerobic, immobilized microbe reactor has been designed, and laboratoryscale units have been constructed. A few of these units have been operated continuously for two years. These reactors were designed for the efficent conversion of carbon to methane in biodegradable molecules and for the effective transfer of that gas. The reactors were operated at 20, 30, and 40°C at residence times of 2-5.5 h. The total chemical oxygen demand (COD) of the sewage varied from 800-2600 mg/L. The resulting gas contained greater than 90% methane and less than 5% CO2. Approximately 32-54% of the influent total carbon was recovered as methane. The reduction in COD varied from 63 to 89%.
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  • 94
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    Biotechnology and Bioengineering 24 (1982), S. 1125-1134 
    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 temperature (15° -40°C) and pH (2.5-6.0) on the continuous growth of bakers' yeast (Saccharomyces cerevisiae) at steady state in 1% ethanol was investigated. Optimal temperature and pH were 30°C and 4.5, respectively. The short-term effect of ethanol concentration (0.1-10.0%) on the yeast growth was assessed in batch culture. Up to 1% of ethanol, the yeast growth increased in function of the ethanol concentration in the medium. The biomass reached a maximum within the interval of 1-4% of ethanol (7.9 and 31.6 g/L, respectively) and decreased at higher concentrations. The residual ethanol concentration in the medium increased rapidly when the initial ethanol concentration exceeded 4%. The best-fit model obtained for growth inhibition as a function of ethanol concentrations was that of Tseng and Wayman: μmS/)K + S( - i (S - Sθ). With this model, the specific growth rate (μ) decreased linearly as the ethanol concentration increased between the threshold value (Sθ) of 11.26 g/L to be fully inhibited at 70.00 g/L (S;) an inhibition constant (i) of 0.0048 g L-1 h-1, a maximum specific growth rate (μm) of 0.284 h-1, and a saturation constant (K) of 0.611 g/L were obtained.
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  • 95
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    Biotechnology and Bioengineering 24 (1982), S. 1135-1144 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Rates of hydraulic transport of water, solute permeabilities, and sieving coefficients of homogeneous κ-carrageenan and bovine serum albumin membranes were measured. These values increased with the water content of membranes. The data show good agreement with the predictions based on the pore model.
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  • 96
    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 and reproducible quantitative method for measuring dissolved oxygen (DO) in uninfected and baculovirus infected cells in culture is described. To establish this method, an industrial DO measuring system for fermentation was employed. During this process the physical characteristics of the cell culture vessel were taken into account permitting a direct readout of DO in microliters per vessel. During these studies, it was experimentally documented that insect cells, particularly baculovirus infected cells, in culture from 1 to 14 days utilize an appreciable level of DO.
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  • 97
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    Biotechnology and Bioengineering 24 (1982), S. 1155-1163 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Saccharomyces cerevisiae NRRL Y-2034, S, uvarum NRRL Y-1347, and Zymomonas mobilis NRRL B-806 each were separately immobilized in a Ca-alginate matrix and incubated in the presence of a free-flowing and continuous 1, 3, 5, 10, or 20% (w/w) glucose solution. In general, the yeast cells, converted 100percnt; of the 1, 3, and 5% glucose to alcohol within 48 h and maintained such a conversion rate for at least two weeks. The bacterium converted ca. 90% (w/w) of the 1, 3, and 5% glucose to alcohol continuously for one week. However, both the yeast and bacterium were inhibited in the highest glucose (20% w/w) solution. All of the immobilized cultures produced some alcohol for at least 14 days. Immobilized S. cerevisiae was the best alcohol producer of all of the glucose concentrations; the yeast yielded 4.7 g ethanol/100 g solution within 72 h in the 10% glucose solution. After 7-8 days in the 10% solution, S. cerevisiae produced ethanol at 100% of theoretical yield (5.0 g ethanol/100 g solution), with a gradual decrease in alcohol production by 14 days. Immobillized S. uvarum produced a maximum of 4.0 g ethanol/100 g solution within 2 days and then declined to ca. 1.0 g ethanol/100 g solution after 7 days continuous fermentation in the 10% glucose solution. Zymomonas mobilis reached its maximum ethanol production at 4 days (4.7 g/100 g solution), and then diminished similarly to S. uvarum. The development of a multiple disk shaft eliminated the problem both of uneven distribution of alginate-encapsulated cells and of glucose channeling within the continuous-flow fermentor column. This invention improved alcohol production about threefold for the yeast cells.
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  • 98
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    Biotechnology and Bioengineering 24 (1982), S. 1183-1190 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Qualitative and quantitative estimations of alcohol-extractable compounds from 14C-glucose-incorporated Scendesmus acutus cells were performed at various intervals of time. After two hours of incubation with 14C-glucose in light, amino acids were synthesized at 65% and sucrose at 26% of the total input label. In the dark incorporation, 30% of the total radioactivity was found in amino acids and 46% in sucrose. Leucine and valine were detected only during the oxidation of glucose in light. The concentration of serine increased more in the presence of light, as compared to dark. These results on the oxidation of glucose are discussed in this article.
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  • 99
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    Biotechnology and Bioengineering 24 (1982), S. 1173-1182 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Optimizations of cell productivity and utility of gaseous substrates were investigated for Alcaligenes hydrogenophilus. Theoretical analyses for the cell productivity and substrate utility were discussed in the light of experimental data. It was proved from the theoretical analyses that the maximum cell productivity was at the following conditions: D = 0.21 h-1, R1 ( = H2 partial pressure/O2 partial pressure) = 2.25 and R2 ( =CO2 partial pressure/O2 partial pressure) = 0.09, i.e., a molal ratio, H2:O2:CO2 = 67.4:29.9:2,7. The Condition which gave the maximum cell productivity also gave high utilities of gaseous substrates. The growth yield for oxygen increased with increasing R1 in chemostat culture, and the growth yield for hydrogen slightly increased with increasing R1. Theoretical cell productivity and substrate and substrate utility were in good agreement with experimental values, taking into account the change of growth yield for oxygen.
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  • 100
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    Biotechnology and Bioengineering 24 (1982), S. 1165-1172 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Microbial lipids produced by Rhodotorula gracilis NRRL Y-1091 grown in continuous culture under nitrogen-limiting condition were evaluated and the effects of growth rate and oxygen concentration on the degree of unsaturatoin of fatty acids studied. As the growth rate increased the protein content of the biomass increased but cell biomass, lipid content, and lipid productivity decreased; the specific lipid production rate remained constant at about 0.012 g lipid/g dry biomass/h. The maximum lipid content recorded was 49.8% (w/w) of the cell mass at a growth rate of 0.02 h-1. The growth rate also affected fatty acid composition; polyunsaturated fatty acids (C18:2 and C18:3) increaded with growth rate while other fatty acids (C16:0, C18:0, C18:1) decreased. Increase in oxygen concentration between 5 and 234μM increased the lipid content without significantly affecting its degree of unsaturation. On the other hand, the degree of unsaturation was significantly affected by specific oxygen uptake rate for this obligate aerobe, Rh. gracilis.
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