摘要:

AbstractThe procedure for isolation ofD‐phenylglycine from its racemic mixture by enzymatic hydrolysis ofL‐enantiomer ofN‐acetyl‐D,L‐phenylglycine is described. For this hydrolysis. aminoacylase fromMicrococcus agilisimmobilized by sorption of DEAE‐cellulose was applied. As is also shown, the course of enzymatic reaction can be directly controlled by spectrophotome

ISSN:0006-3592    

DOI:10.1002/bit.260230802

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe oxidation of ammonium ion to nitrite and nitrate ion (nitrification) has been studied in a laboratory scale fluidized sand bed reactor with attached microbial growth. The undefined population ofNitrobacteraceaorganisms were immobilized on the sand particles by natural attachment after 2–3 months of adaptation. General balance equations have been formulated for a recycle reactor and oxygenation tank system. Kinetic experiments in the reactor and in a microrespirometer have been analyzed in terms of double Michaelis–Menten rate expression for the nitrogenous reactants and dissolved oxygen. Dynamic simulation of the batch integral reactor system was used to establish the error in the kinetic constant which arose due to assuming differential behavior. Design guidelines have been developed for the oxygen requirements in terms of oxygen transfer coefficients, oxygen enrichment, and liquid recycle r

ISSN:0006-3592    

DOI:10.1002/bit.260230803

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

年代:1981

数据来源: WILEY

摘要:

AbstractContinuous hydrolysis of triglyceride in organic solvent systems usingRhizopus arrhizusmycelia as a source of insolubilized lipase has been studied in packed‐bed and stirred‐tank reactors. Typically a packed bed reactor containing 1 g of mycelia fed at 1 mL/min with a solution of 2.5% (w/v) olive oil in di‐isopropyl ether gave a fatty acid yield of 45% at 30°C. The optimum water concentration was found to be 0.17% (w/v) except under conditions of high oil feed concentration and high yield where no optimum was established. No temperature optimum was observed over the range 20–55°C. Calculated activation energies of 13–20 kJ/mol, depending on temperature, were lower, whileKm(app) values of 0.1–0.3Mwere higher than those for hydrolysis in conventional aqueous emulsion systems. No evidence of any significant diffusional limitation, which could account for these values, was obtained. The mycelia showed a loss of activity of 0.6–1.0%h at 30°C. The packed bed proved markedly superior to the stirred tank

ISSN:0006-3592    

DOI:10.1002/bit.260230804

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

年代:1981

数据来源: WILEY

摘要:

AbstractLactate dehydrogenase (LDH) was adsorbed on low‐(γ, η) and high ‐(θ, α) temperature forms of alumina. θ‐Al2O3exhibited the greatest adsorption ability. The maximum adsorption value was 30 mg LDH/g of a carrier. The conditions for irreversible adsorption have been determined. An adsorption isotherm on θ‐Al2O3for pH 6.0 has been obtained; the LDHadssurface area and the carrier surface portion accessible to the enzyme molecules have been calculated. The reaction kinetic parameter were determined by taking into account the reaction proceeding in the intradiffusional region. The specific catalytic activity (Aspec) of LDHadsat small surface coverage of θ‐Al2O3is five times less thanAspecof the native enzyme andKMimmwith respect to NADH exceedsKMnatby two orders or magnitude. The is evidence for a strong LDH–Al2O3interaction and a considerable deformation of the enzyme globule.AspecandKMdecrease as the amount of the enzyme attached to the carrier increases. Due to adsorption. LDH becomes thermostable and durable. The LDHadssamples conserve 20–40% of their activity at room tempe

ISSN:0006-3592    

DOI:10.1002/bit.260230805

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

年代:1981

数据来源: WILEY

摘要:

AbstractA mathematical model for the aerobic growth ofSaccharomyces cerevisiaein both batch and continuous culture is described. It was based on the experimental observation that the respiratory capacity of organism may become saturated and exhibit a maximum specific oxygen uptake rate after suitable adaptation. This experimental observation led to the possibility that transport into and out of the mitochondrion was of major importance in the overall metabolism ofS. cerevisiaeand was subject to long‐term adaptation. Consistent with this observation a distributed model was proposed which. as its basis, assumed the control of repression or inhibition of the uptake rates of other substrates. No other regulation of fermentation and respiration was assumed. The model provided a suitable structure allowing precise quantification of the changes in rate and stoichiometry of energy production. The model clearly indicated that growth under the wide range of experimental conditions reported could not be predicted using constant values for the maximum specific respiratory rate of constant values ofYATP(g biomass/mol ATP) and PO ratio of (mol ATP/atom oxygen). The causes of the variation in the respiratory rate were not determined and it was concluded that a more detailed analysis (reported subsequently) was required. The variation ofYATPand PO ratio with specific growth rate implied that the efficiency of ATP generation or ATP utilization decreased with increasing specific growth rate. It was concluded that it was not possible to quantify the individual effect ofYATPand PO ratio until independent means for their reliable estimation is availabl

ISSN:0006-3592    

DOI:10.1002/bit.260230806

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

年代:1981

数据来源: WILEY

摘要:

AbstractA computer simulation of the integration of the internal energy metabolism and the cell cycle ofSaccharomyces cerevisiaeis described. This was attempted, for the first time, as a result of the observation that in this organism the overall or average external metabolic exchange rates often differed considerably from the internal metabolic fluxes which they are normally assumed to represent. This was the result of such factors as the variation in the nature of the metabolism of the organism depending on its stage in the cell cycle and redox interactions between anabolism and catabolism. The overall result of this simulation is the prediction of the internal metabolic fluxes consistent with the experimentally determined external fluxes. While these simulation depend on the assumption regarding the energetics and cell cycle ofSaccharomyces cerevisiae, they provide a means of examining with precision such processes as the energetics of cell growth and cell cycle variation. As a result, within these limitation, they allow the systematic study of coordinated cell control. Such an approach provides a useful and largely unused adjunct to the experimental approaches which have attempted the study of coordinated metabolic regulation.

ISSN:0006-3592    

DOI:10.1002/bit.260230807

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe main objectives of this study were (1) to determine the optimum frequency for transferring a fixed population ofEisenia foetidainto fresh surroundings to effect maximum production of earthworm biomass, (2) to determine carrying capacity and maximum production ofE. foetidabiomass per unit area–volume–time at 24°C, and (3) to measure the nucleic acid concentration of this earthworm. Population were rapidly decimated in limed peat moss with horse manure as food when transferred weekly or when held for ten weeks in the same substrate; no significant differences and high survival obtained at intermediate intervals. Significantly more cocoons were produced when transfers were made every two weeks, and a trend was seen toward a lower level of cocoon production with length of detention in substrate. The growth rate of adults was approximately similar in relation to the frequency of transfer, as was biomass, at transfer frequencies of every 2 to 9 weeks. One interpretation of the data is that a detention interval of 6 to 8 weeks is optimum for maximizing production of biomass; eight weeks is the interval commonly selected in commercial practices. Carrying was 9.5 g live weight on a surface area–volume of 24 cm2–110 cm3with horse manure as food on 20 g of soil as substrate; maximum production in this space was 2 g live weight in 7 weeks, which extrapolates to 6685 kg protein/ha yr. Nucleic acid concentration was 2.9%, which falls below values of about 6–28% obtained for microbes, and may exceed values for mammalian muscle by abo

ISSN:0006-3592    

DOI:10.1002/bit.260230808

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

年代:1981

数据来源: WILEY

摘要:

AbstractSaccharomyces cerevisiaecells were immobilized in calcium alginate beads for use in the continuous production of ethanol. Yeasts were grown in medium supplemented with ethanol to selectively screen for a culture which showed the greatest tolerance to ethanol inhibition. Yeast beads were produced from a yeast slurry containing 1.5% alginate (w/v) which was added as drops to 0.05MCaCl2solution. To determine their optimum fermentation parameters, ethanol production using glucose as a substrate was monitored in batch systems at varying physiological conditions (temperature, pH, ethanol concentration), cell densities, and gel concentration. The data obtained were compared to optimum free cell ethanol fermentation parameters. The immobilized yeast cells examined in a packed‐bed reactor system operated under optimized parameters derived from batch‐immobilized yeast cell experiments. Ethanol production rates, as well as residual sugar concentration were monitored at different feedstock flow ra

ISSN:0006-3592    

DOI:10.1002/bit.260230809

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe quantitative effects of substrate concentration, yeast concentration, and nutrient supplementation on ethanol content, fermentation time, and ethanol productivity were investigated in a Box–Wilson central composite design experiment, consisting of five levels of each variable, High substrate concentration, up to 30° Brix, resulted in higher ethanol content (i.e., up to 15.7% w/v or 19.6% v/v) but longer fermentation time and hence lower ethanol productivity. Increasing yeast concentration, on the other hand, resulted in shorter fermentation time and higher productivity. The highest ethanol productivity of about 21 g EiOH/L h was obtained at low substrate concentration (i.e., 12° Brix), low alcohol content (i.e., 6% by weight), high yeast concentration (i.e., 4.4%), and high supplementation of yeast extract (i.e., 2.8). Productivity of this magnitude is substantially higher that that of the traditional batch fermentation of fed‐batch fermentation. It is comparable to the results of continuous fermentation but lower than those of vacuum fermentation but lower than those of vacuum fermentation. Optimal conditions for maximal ethanol productivity can be established by a multiple regression analysis technique and by plotting the contours of constant response to conform to the constraints of individual opera

ISSN:0006-3592    

DOI:10.1002/bit.260230810

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

年代:1981

数据来源: WILEY

摘要:

AbstractThe Production of cellulases and Hemicellulases was studied withTrichoderma reeseiRut C‐30, This organism produced, together with high cellulase activities, considerable amounts of xylanases and β‐glucosidase. Three cellulose concentration (1, 2.5, and 5.0%) were examined to determined the maximum levels of cellulase activity obtainable in submerged culture. Temperature and pH profiling was used to increase cell mass to maximum levels within two days and thereby enhancing fermentor productivity at higher substrate levels. The effect of temperature, pH, Tween‐80 concentration, carbon sources, and substrate concentration on the ration of mycelial growth and extracellulose enzyme production are des

ISSN:0006-3592    

DOI:10.1002/bit.260230811

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

年代:1981

数据来源: WILEY