摘要:

AbstractIn the present study optimal policies have been evaluated for the production of gramicidin S in multistage continuous culture. An economic objective function was developed which took account of the number and size of the reaction vessels, the costs involved in antibiotic extraction, substrate costs, and variability in the selling price of gramicidin S. Optimal values of temperature and pH were 28.3 and 7.24, respectively, and independent of the stage in the system. Using the discrete maximum principle it was shown that a “cut‐off” point existed for the selling price of the antibiotic below which production was no longer profitable. Furthermore it was established that beyond 3 stages in a multistage system, only marginal gains in profitability could be made (viz., an increase in 6.3% on going from a 3‐stage to a 4‐stag

ISSN:0006-3592    

DOI:10.1002/bit.260140202

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

年代:1972

数据来源: WILEY

摘要:

AbstractA method for large reduction of nucleic acid content ofSaccharomyces cercvisaeis described. This method is based on yeast suspension in phosphate solution (50mM), heat shock following the Maul et al. (Nature228, 181 (1970)) procedure, and dialysis or washing with phosphate solution of alkaline pH. When the extraction process is carried out at pH 12, sodium phosphate can be replaced by sodium chloride with the same results. Under these conditions the protein mg/nucleic acid mg ratio attains values of 50–60, (10 times the initial ratio). At this alkaline pH, washing can be done with distilled water with equally good result

ISSN:0006-3592    

DOI:10.1002/bit.260140203

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe kinetic behavior of heterogeneous microbial populations of sewage origin was studied in a single‐stage isothermal continuous flow completely mixed aeration tank. A series of experiments were carried out at various dilution rates using glucose as the growth limiting substrate. The steady‐state behavior of the system was observed at each dilution rate and the results were found to fit fairly well with the steady‐state equation bayed on the Monod model with an endogenous respiration term included, i.e., μ = μmS/(Ks+S) −Kd. The growth kinetics of cells harvested at steady state for each dilution rate were studied using batch experiments. The multiple response data of the system as functions of time were used to estimate the parameter values in the above kinetic model. It was found that values of the growth parameters changed significantly and systematically with cell population. For example, values of μmwere high at high dilution rates and low at low dilution rates. It was also found that only those batch growth parameters from cells obtained at fairly high dilution rates are comparable with those estimated by the results of steady‐state operations. The results of this investigation suggest that (1) different cell populations pre dominated at different steady‐state dilution rates, with high dilution rates resulting in predominantly fast‐growing organisms and low dilution rates resulting in predominantly slow‐growing cells, and (2) risk exists in any randomly picked batch experiment to predict the steady‐state behavior of the system when heterogeneous microbial popu

ISSN:0006-3592    

DOI:10.1002/bit.260140204

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

年代:1972

数据来源: WILEY

摘要:

AbstractIt is shown theoretically that in continuous reactions the rate of catalase inactivation by hydrogen peroxide depends on the type of reactor and the order of the chemical reaction.

ISSN:0006-3592    

DOI:10.1002/bit.260140205

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe kinetic behavior of heterogeneous microbial populations of sewage origin was studied in a single‐stage, isothermal, continuous flow, completely mixed aeration tank. A series of experiments were carried out at various dilutions rates using glucose as the limiting substrate. The cell dry weight and substrate concentration in terms of chemical oxygen demand (COD) were continuously monitored. The results indicate that reproducible steady‐state conditions can generally be obtained; however, multiple steady states were observed at dilution rates near washout. At low dilution rates (below about 0.1 hr−1) the contribution of microorganism decay became appreciable. Using the multiresponse data of cell dry weight and COD, the parameter values in various existing growth models were estimated. The analyses of variance and residuals revealed that models proposed by Moser, Monod, and Contois, each with a decay term added, were significantly better than the other models which were t

ISSN:0006-3592    

DOI:10.1002/bit.260140206

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe fermentation kinetics of the homofermentative organismLactobacillus delbrueckiiin a glucose‐yeast extract medium is studied in both batch and continuous culture under conditions of controlled pH. From a graphical analysis of the batch data, a mathematical model of the process is derived which relates bacterial growth, glucose utilization, and lactic acid formation. The parameters in the model represent the activity of the organism and are a function of pH, having a maximum value at about 5.90. In a continuous stirred tank fermentor (CSTF), the effect of pH, feed concentration, and residence time is observed. The feed medium is a constant ratio of two parts glucose to one part yeast extract plus added mineral salts. An approximate prediction of the steady‐state behavior of the CSTF can be made using a method based on the kinetic model derived for the batch case. In making step changes from one steady state to another, the transient response is observed. Using the kinetic model to simulate the transient period, the calculated behavior qualitatively predicts the observed respo

ISSN:0006-3592    

DOI:10.1002/bit.260140207

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

年代:1972

数据来源: WILEY

摘要:

AbstractIf inhibitory substrates are being utilized in a well‐stirred biological reactor, microbiological growth on the walls of the reactor can create a scale‐up problem. A simple model is proposed which shows that without such growth, of the three existing steady states only one is stable and nontrivial, but with wall growth the trivial, stable, steady state (washout) is impossible. In addition, wall growth reduces the region over which three steady states are feasible and reduces the minimum residence time for which there is only one steady state that corresponds to a high conversion. Thus, a laboratory process with a high surface area to volume ratio can give an over optimistic prediction of both necessary residence; time and stability of the full scale process unless wall growth is accounted

ISSN:0006-3592    

DOI:10.1002/bit.260140208

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

年代:1972

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260140209

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

年代:1972

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260140210

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

年代:1972

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260140211

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

年代:1972

数据来源: WILEY