摘要:

AbstractNonphosphorylating electron transport particles (ETP) prepared from beef heart mitochondrion were immobilized in agar gel. The immobilized ETP showed an oxidase activity to both NADH and succinate. The immobilized ETP was reusable. An electrochemical device for the determination of either NADH or succinate was assembled consisting of the membrane‐bound ETP and an oxygen probe. The response to succinate was specifically inhibited by the addition of malonat

ISSN:0006-3592    

DOI:10.1002/bit.260220902

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe production of tylosin and related compounds byStreptomyces fradiaeNRRL 2702 was studied in batch and chemostat cultures using a soluble synthetic medium. In batch culture, a trophophase–idiophase kinetic pattern was observed with tylosin, macrocin, and relomycin accumulating in the idiophase. When the organism was grown in chemostat culture, the specific rate of production of tylosin and related compounds (qtylosin) was found to be a function of the growth rate. The maximum value of (qtylosin) was observed whenD= 0.017 hr−1. At this growth rate only tylosin and relomycin accumulated in the medium. By varying the concentration of glucose in the ingoing medium it was possible to study the effects of glucose on tylosin synthesis in chemostat cultures. At a growth rate of 0.017 hr−1, the maximum value ofqtylosinwas 0.71 mg tylosin/g dry weight (DW)/hr when the glucose uptake rate was 7 mg glucose/g DW‐hr. This value ofqtylosinwas 40% greater than the maximumqtylosinobserved in batch culture. When glycerol was substituted for glucose in the medium, it was possible in chemostat culutures to get values ofqtylosinapproximately 20% greater than those obtained with glucose at the same uptake rate. By varying the concentration of sodium glutamate in the ingoing medium it was possible to show that increasing the specific uptake rate of sodium glutamate increased the values ofqtylosinobtained. Similar chemostat experiments where the inorganic phosphate concentration in the ingoing medium was varied showed that increased the uptake of phosphate decreased the values ofqtylosinobtained. Also increasing the uptake rate of phosphate increased the relomycin‐to‐tylosin ratio. By taking into consideration the suppressing effects of glucose and the stimulating effects of sodium glutamate on tylosin synthesis, it was possible to formulate a medium that resulted in a value ofqtylosinof 1.1 mg/g/hr being obtained at a growth rate of 0.03 hr−1. Batch fermentations with this medium did not follow a trophophase–idiophase kinetic pattern, but instead tylosin was actively synthesized during a period of rapid

ISSN:0006-3592    

DOI:10.1002/bit.260220903

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe influence of dilution rate on the production of biomass, ethanol, and invertase in an aerobic culture ofSaccharomyces carlsbergensiswas studied in a glucose‐limited chemostat culture. A kinetic model was developed to analyze the biphasic growth of yeast on both the glucose remaining and the ethanol produced in the culture. The model assumes a double effect where glucose regulates the flux of glucose catabolism (respiration and aerobic fermentation) and the ethanol utilization in yeast cells. The model could successfully demonstrate the experimental results of a chemostat culture featuring the monotonic decrease of biomass concentration with an increase of dilution rate higher than 0.2 hr−1as well as the maximum ethanol concentration at a particular dilution rate around 0.5 hr−1. Some supplementary data were collected from an ethanol‐limited aerobic chemostat culture and a glucose‐limited anaerobic chemostat culture to use in the model calculation. Some parametric constants of cell growth, ethanol production, and invertase formation were determined in batch cultures under aerobic and anaerobic states as summarized in a table in comparison with the chemostat data. Using the constants, a prediction of the optimal control of a glucose fed‐batch yeast culture was conducted in connection with an experiment for harvesting a high yield of yeast cells with high inverta

ISSN:0006-3592    

DOI:10.1002/bit.260220904

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe partition of hexadecane to the cell surface ofCandida tropicaliswas measured by incubating heat‐inactivated cells with hexadecane‐1‐14C on a gyratory shaker. The free hexadecane was separated by centrifuging the cells through a 15% sucrose solution, and the partitioned hexadecane was quantified by scintillation spectrometry of the samples from the resulting cell sediment. Heat‐inactivated cells did not take up hexadecane as determined by a membrane filtration technique involving organic solvent washing. The partitioning was a time‐dependent process. The velocity increased by increasing the shake rate of te shaker. At 360 rpm and with baffled flasks, saturation of the cell surface with hexadecane was obtained after a 20 min incubation period. The amount of hexadecane partitioned depended on the initial hexadecane‐to‐cell concentration ratio. At a ratio of 5 μmol/mg cell protein the highest amount of hexadecane partitioned was measured at 2100 μmol/mg cell protein. At ratios higher than 6 μmol/mg cell protein the cells were no longer sedimentable by centrifugation. The partition of hexadecane to the cell surface was affected by removing the surface layer of the cell wall by Pronase treatment and by using detergents in the partition assay. Pronase treatment lowered the amount of hexadecane partitioned as a consequence of the removal of the lipophilic layer of the cell surface. Detergents influence the partition coefficient and also lowered the amount of hexadecane partitioning to the cell surface. At a low shaking intensity (280 rpm, unbaffled flasks), after Pronase treatment, and in the presence of detergents he uptake of hexadecane by the cells was limited by

ISSN:0006-3592    

DOI:10.1002/bit.260220905

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe bed expansion behavior of liquid fluidized beds of char particles coated with attached microbial growth of denitrifying mixed bacteria was studied experimentally to obtain an expression that relates the bed expansion to the liquid velocity for liquid fluidized beds of composite particles. As for liquid beds of homogeneous spheres, the bed voidage and the liquid velocityvzfor liquid fluidized beds of biomass‐coated particles were found to be related asvz/Vi= ∈n. The correlations recommended by Richardson and Zaki for homogeneous spheres are found to be satisfactory for the estimation of the constantn, but only under certain conditions for the constan

ISSN:0006-3592    

DOI:10.1002/bit.260220906

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

年代:1980

数据来源: WILEY

摘要:

AbstractExperimental studies of the growth of a natural microbial population on a synthetic liquid effluent containing sugar, sodium alginate, and nutrients showed that: (I) the concentration of substrates in the feed to an activated sludge process exerts a significant effect upon its effluent chemical oxygen demand (COD) and (ii) there is an optimum sludge age for achieving minimum effluent COD, given by the relationship: optimum growth rate ∝ (feed COD)0.5. These were explained by incorporating the concept of product formation into existing activated‐sludge theory, which showed that at sludge ages longer than optimum, effluent COD increased due to product formation; at shorter sludge ages, the effluent COD increased owing to an increased concentration of degradable substra

ISSN:0006-3592    

DOI:10.1002/bit.260220907

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe supply of heterotrophically growing suspensions ofAlcaligenes eutrophusPHB−4 with oxygen formed by the continuous addition of H2O2in the presence of bovine liver catalase was found to be restricted to well‐defined conditions. The catalase‐H2O2system proved to be suitable during the growth at low cell densities equivalent to 2 g dry weight/liter. When under these conditions the oxygen concentration was held constant at 1.8 mg O2/liter, the cells grew for 6–8 hr at a rate almost identical to that observed with conventional aeration. However, aeration with H2O2for longer durations (10–20 hr) and at higher cell densities (5−20 g dry weight/liter) led invariably to cell damage and retardation of growth. The impairment of growth observed during the oxygen supply by the catalase−H2O2system was traced back to the formation of gradually increasing steady‐state concentrations of H2O2in the medium. Possible sites of cell damage by H2O2such as membrane function, excretion and function of siderophores, and synthesis of cell polymers have been studied, and the cytotoxic mechanism of low concentrations of H2

ISSN:0006-3592    

DOI:10.1002/bit.260220908

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

年代:1980

数据来源: WILEY

摘要:

AbstractEmpirical estimations of H2O2concentration in a system containing bovine liver catalase and continually supplied with H2O2were done to evaluate the efficiency of the enzyme to cleave H2O2. It was found that the continuous addition of H2O2leads to the formation of steady‐state concentrations of H2O2in the medium. At a constant catalase concentration both the level and the duration of the steady state are dependent on the flow rate of H2O2. The increase of the catalase concentration in the medium does not change the steady‐state level, it merely leads to the maintenance of the steady state for longer durations. At higher flow rates of H2O2, no steady state could be maintained, even when catalase was present in high excess. The incomplete cleavage of H2O2by catalase under these conditions is due to the low affinity of catalase toward H2O2(highKmvalue, apparentKm= 0.1MH2O2) and to the rapid inactivation of the enzyme during the continuous addition of H

ISSN:0006-3592    

DOI:10.1002/bit.260220909

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

年代:1980

数据来源: WILEY

摘要:

AbstractBatch and single‐flow four‐stage continuous ethanol fermentations of bagasse hydrolysate have been investigated at pH 4.0 and 30°C with a strain of the yeastSaccharomyces cerevisiae. The studies were carried out in the laboratory four‐stage cascade continuous stirred‐tank fermentors at varying feed glucose concentrations (10, 14, 18, and 22%). The range of dilution rates employed varied from 0.05 to 0.2 hr−1. The hydrolysate was supplemented with a cheap nitrogen source (CNS), CaCl2·H2O and MgSO4·7H2O. A 2% (v/v) CNS concentration was found to be sufficient to avoid growth limitation at a glucose concentration of 116 g/liter. The conditions of continuous culture in a multistage system are predicted by a graphical method based on batch‐culture data. The results thus obtained are compared with those predicted by kinetic models and with the experimental results. The variations between the results obtained experimentally and those computed either by a kinetic model or by graphical analyses were found to be within the limits of experimental error. The solutions based on the concept of minimum residence time necessary to achieve the desired biomass or product concentrations are

ISSN:0006-3592    

DOI:10.1002/bit.260220910

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

年代:1980

数据来源: WILEY

摘要:

AbstractMass balance regularities are used to develop equations for the estimation of maintenance coefficients, true growth yields, and true product yields when nitrate is the nitrogen source. An available electron balance is presented that includes the uptake of nitrate. The application of the theory is illustrated using continuous‐culture data of Stouthamer and Bettenhaussen in whichAerobacter aerogenesis grown aerobically with KNO3as the nitrogen sourc

ISSN:0006-3592    

DOI:10.1002/bit.260220911

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

年代:1980

数据来源: WILEY