摘要:

AbstractThe kinetics of the reversible fumarase reaction of immobilizedBrevibacterium ammoniagenescells and the decay behavior of enzyme activity were investigated in a plug flow system. The time course of the reaction in the immobilized cell column was well explained by the time‐conversion equation including the apparent kinetic constants of the immobilized cell enzyme. The decay rate of fumarase activity was faster in the upper sections of the column (inlet side of the substrate solution) compared with the lower sections when 1Msodium fumarate (pH 7.0) was continuously passed through the column at 37°C. It was shown that the decay rate of the fumarase activity in the immobilized cell column depends on the flow rate of the substrate solution. The effect of flow rate on the decay rate of enzyme activity was considered to be related to the rate of contamination of enzyme with poisonous substances derived from the substrate solution or to the rate of leakage of enzyme stabilizers and/or enzyme itself from the immobilized cel

ISSN:0006-3592    

DOI:10.1002/bit.260190802

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractTrypsin was coupled on an agarose gel which was modified with a spiropyran compound. The trypsin–spiropyran (agarose) gel showed reverse photochromism. The activity of the trypsin–spiropyran gel in the dark was 12% of that of native trypsin, and it was higher than that under visible light. The apparent Michaelis constant of the trypsin–spiropyran gel in the dark was larger than that under visible light. On the other hand, the maximum velocity in the dark was higher than that under visible light. The optimum pH of the trypsin–spiropyran gel in the dark was the same as that under visible light. Immobilized trypsin was stable in the pH range from 3 to 9. The trypsin–spiropyran gel was more stable against heat than the nativ

ISSN:0006-3592    

DOI:10.1002/bit.260190803

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractCell recycle and vacuum fermentation systems were developed for continuous ethanol production. Cell recycle was employed in both atmospheric pressure and vacuum fermentations to achieve high cell densities and rapid ethanol fermentation rates. Studies were conducted withSaccharomyces cerevisiae(ATCC No. 4126) at a fermentation temperature of 35°C. Employing a 10% glucose feed, a cell density of 50 g dry wt/liter was obtained in atmospheric‐cell recycle fermentations which produced a fermentor ethanol productivity of 29.0 g/liter‐hr. The vacuum fermentor eliminated ethanol inhibition by boiling away ethanol from the fermenting beer as it was formed. This permitted the rapid and complete fermentation of concentrated sugar solutions. At a total pressure of 50 mmHg and using a 33.4% glucose feed, ethanol productivities of 82 and 40 g/liter‐hr were achieved with the vacuum system with and without cell recycle, respectively. Fermentor ethanol productivities were thus increased as much as twelvefold over conventional continuous fermentations. In order to maintain a viable yeast culture in the vacuum fermentor, a bleed of fermented broth had to be continuously withdrawn to remove nonvolatile compounds. It was also necessary to sparge the vacuum fermentor with pure oxygen to satisfy the trace oxygen requirement of the fermenting

ISSN:0006-3592    

DOI:10.1002/bit.260190804

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractA mathematical model is presented that describes the concentration of an amino acid in total cell protein as a function of its concentration in individual cell proteins or in sets of cell proteins. The resulting equation makes it possible to calculate how the makeup of cell proteins must change to obtain a specified alteration in the content of an amino acid in the total cell protein. It is recognized that protein species or sets of proteins that are distinguished by being richer or poorer in a key amino acid than the overall protein must undergo considerable variations in content. The necessary extent of these shifts suggests that the amino acid composition of total cell protein is not likely to be affected significantly by variations in the cultivation conditions.

ISSN:0006-3592    

DOI:10.1002/bit.260190805

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractGlucose‐limited chemostat cultures ofCandida utiliswere cultivated at various pH levels (3.0–7.5), temperatures (15–37.5°C), dilution rates (0.06–0.42 hr−1), and with one of two nitrogen sources (NH 4+or NO 3−).Enterobacter aerogeneswas also cultivated in the chemostat under nitrogen and phosphorus limitations. The amino acid profile of total cell protein is expressed as the content of each amino acid relative to the sum of all amino acids recovered after acid hydrolysis. Cell residues obtained after hot trichloroacetic acid extraction display small variations in amino acid profile. Some of these variations correlate with the growth rate at satisfactory levels of statistical significance. InC. utilis, the correlations cover increased levels of lysine, arginine, and leucine and decreased levels of serine and glutamic acid with increased “reduced dilution rate” (D/Dc). InE. aerogenes, increased levels of lysine and arginine and a decreased level of glutamic acid correlate with increased dilution rate. The directions of most of these correlations and the extents of those pertaining to lysine and arginine are consistent with the change predicted to occur simultaneously in the relative level of the rib

ISSN:0006-3592    

DOI:10.1002/bit.260190806

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractBiological kinetic behaviors of the oxygenated and aerated activated sludge process were studied and compared in both once‐through and constant sludge recycle systems. The models derived by Herbert, Elsworth, and Telling [J. Gen. Microbiol.,14, 601 (1956)] and Ramanathan and Gaudy [Biotechnol. Bioeng.,11, 207 (1969)] were used for the studies of once‐through and constant sludge recycle systems, respectively. Soft drink waste water was used for the growth limiting substrate. Temperature was controlled within 30 ± 2°C. The influent substrate concentration was maintained at 1,000 mg/liter. The experiments were conducted at various dilution rates (from\documentclass{article}\pagestyle{empty}\begin{document}$ \frac{1}{9} $\end{document}to 1/1.0 hr−1), and recycle solids concentration values (from 5,000 to 10,000 mg/liter), with hydraulic recycle ratio, α, at 0.3.Biological kinetic constants were evaluated and compared. It was found that these constants were different for the aerated and oxygenated systems within a certain range of dilution rates studied. The critical dilution rates for diluting out effluent chemical oxygen demand (COD) occurred at 0.1 and 0.2 hr−1in the once‐through operation, and 0.2 and 0.4 hr−1in the sludge recycle operation for aerated and oxygenated systems, respectively. Observed sludge yield values and specific growth rate were varied with the type of aeration and with and without constant sludge recycle concentration applied. Sludge carbohydrates and proteins content in the oxygenation system (cell recycle) were 10.1–21.6% and 35.6–52.2%. Sludge volume index in the air and oxygenation systems varied from 41.4 to 354 and 31.9 to

ISSN:0006-3592    

DOI:10.1002/bit.260190807

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractCellulase was immobilized in a collagen fibril matrix, and no leakage of cellulase from the collagen fibril matrix was observed. The immobilized cellulase was more stable than the native cellulase. The substrate cellulose was hydrolyzed quantitatively with immobilized cellulase. The final reaction product was identified as glucose. Immobilized cellulase was used in a fluidized bed reactor where the pressure drop of the fluidized bed reactor was low and constant. Cellulose was hydrolyzed to glucose by the cellulase‐bead fluidized bed reactor. The minimum flow velocity (Umf) was 0.5 cm/sec and the optimum flow velocity of the cellulose hydrolysis was 1 cm/se

ISSN:0006-3592    

DOI:10.1002/bit.260190808

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

摘要:

AbstractA model for the growth of an organism on multiple substrates was developed, assuming that each substrate has a competitive inhibition effect on the uptake of other substrates. The model was extended to examine mixed substrates, showing that the coexistence of several species at steady state in continuous cultures is possible, even when all the organisms all strongly prefer the one substrate. The diversity of nutrient sources in a real system may be a key factor in supporting a heterogeneous microbial population.

ISSN:0006-3592    

DOI:10.1002/bit.260190809

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260190810

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260190811

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1977

数据来源: WILEY