摘要:

AbstractA well‐mixed biological reactor with continuous addition of biological solids was subjected to sinusoidal variations in inlet substrate concentration. The phase lag between inlet and outlet concentrations increased with increasing frequency. The deviation of measured substrate concentrations from initial steady‐state concentrations was observed to have a maximum near a frequency of 1 cycle per residence time. Measured concentrations of substrate and biomass in the reactor differed significantly from concentrations predicted by the Monod kinetic mo

ISSN:0006-3592    

DOI:10.1002/bit.260180102

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe criterion for the oxygen limitation of substrate uptake in microbial film fermenters is expressed in terms of diffusion coefficients, utilization coefficients, and the free solution concentrations of substrate and oxygen. It is proposed that the ideal film thickness in such fermenters is equal to the penetration depth of the limiting substrate. The ideal film thickness is calculated, in terms of the parameters contained in the criterion for oxygen limitation, for three separate kinetic rate expressions. It is found that for the air–glucose–microbe system a simplified kinetic rate expression can be used and the region of dependence on two substrates is shown to be very limited. This is not true for other systems. Maximum uptake rates are calculated for a range of concentrations. Finally, it is shown that the procedure used can be generalized to determine the limiting substrate in a multisubstrate system and to calculate ideal film thickness and uptake rates for any pair of substrates where the kinetics of substrate uptake are known for the individual microorgan

ISSN:0006-3592    

DOI:10.1002/bit.260180103

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

年代:1976

数据来源: WILEY

摘要:

AbstractLittle is known about techniques for applying untreated microbial cells containing enzymes directly to industrial processes as a biocatalyst. The kinetic behavior of α‐galactosidase‐containing spherical pellets which are formed naturally under given conditions in a submerged culture ofMortierella vinaceawas studied on the hydrolysis of PNPG (p‐nitrophenyl–α–D‐galactopyranoside). The effect of intraparticle diffusion on the overall reaction rate was assessed by the use of an effectiveness factor, which was calculated by the approximate solution to the equation derived from the mass balance within a pellet. The experimental effectiveness factors were found to be represented as a single function of the modified Thiele modulus, including such parameters as pellet size, enzyme concentration in the pellet, and substrate concentration. As the diffusional effect became more significant, the marked substrate inhibition as seen for a five enzyme disappeared gradually. The effect of product inhibition on the pellets was much weaker than that for a free enzyme at a given substrate concentration. In the region of diffusion controlled reaction, it was found that the rate is proportional to the square root of the enzyme concentration in the pellet. In addition, similarly to what was reported previously for a free enzyme, the reaction in a batch system was found to be approximately representable as simple first‐order kinetics in which the rate constant was dependent on the initial substrat

ISSN:0006-3592    

DOI:10.1002/bit.260180104

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

年代:1976

数据来源: WILEY

摘要:

AbstractA graphical method is outlined in order to calculate the conversion under combined intra‐ and extraparticle transport limitations using the existing effectiveness factor charts for intraparticle diffusion.This method is applied to the case of an immobilized enzyme, assuming that the kinetics are of the Michaelis‐Menten t

ISSN:0006-3592    

DOI:10.1002/bit.260180105

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

年代:1976

数据来源: WILEY

摘要:

AbstractTransient experiments were conducted on aPseudomomasutilizing phenol in a continuous culture by disturbing the influent substrate concentration and dilution rate. Two stable steady states existed for some ranges of the parameters. Highly damped oscillations were observed in approaching a new high conversion steady state or in returning to a new high conversion steady state following a small disturbance. When a large disturbance was applied there was a smooth (overdamped) approach to a new low conversion steady state.The observed oscillatory behavior for small disturbances was predicted by a modified Powell‐Ierusalemskii bottleneck model, but could not be predicted by a Monod‐Haldane model; neither model was accurate for predicting the effect of large disturbances.A constant wall growth factor was used to account for microbial film activity, and the existence of two stable states was directly due to the presence of the f

ISSN:0006-3592    

DOI:10.1002/bit.260180106

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

年代:1976

数据来源: WILEY

摘要:

AbstractEscherichia coliB,Escherichia coliMRE 600,Escherichia coliK 12‐3300,Pseudomonas fluorescens, andAerobacter aerogeneswere grown exponentially in a bench‐scale fermentor to cell concentrations in the range of 20 to 41 g dry cells/liter at 30°C and 30 to 55 g dry cells/liter at 25°C. The high cell concentrations were achieved in a growth system previously described for growth ofEscherichia coliW (Biotechnol. Bioeng.,16, 933 (1974);ibid.17, 227 (1975)). Various enzyme activity levels in the high‐concentration cells were compared to those in cells grown in conventional low‐density cultures. No significant differences were found. The culture supernatants were found to be essentially free of high‐molecular weight metabolic or cell lysis products. Yield constants for glucose, nitrogen, oxygen, and phosphorus were also determined in the dense cultures and some of their relations to the growth conditions ar

ISSN:0006-3592    

DOI:10.1002/bit.260180107

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe apparent activation energy ofN‐α‐benzoyl‐L‐arginine‐ethyl ester (BAEE) hydrolysis by immobilized trypsin varies with the bulk substrate concentration from its maximum value, comparable to that of the free enzyme, to considerably lower values. Thus, with a concentration change from 3 × 10−2to 10−4Mthe apparent activation energy diminishes from 9.5 to 4.5 kcal/mol. This experimental finding is interpreted to be due to Michaelis‐type kinetics in a heterogeneous system, in one case reflecting the temperature dependence of the maximal enzyme reaction rate, in another case illustrating the diffusion limited overall reaction at low substrate concentrations. As a consequence it may not be feasible to operate a reaction at elevated temperatures in a high conversion range, since diffusion limitation may restrict the enhancement of the overall reaction rate. Some further data are given concerning the buffer effect on the reaction rate, which should occur due to its limitation by proton transfer in the b

ISSN:0006-3592    

DOI:10.1002/bit.260180108

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

年代:1976

数据来源: WILEY

摘要:

AbstractTrypsin was covalently immobilized on porous glass in the presence and absence of a specific substrate and reacted in various organic solvents of different dielectric constants. Optimum solvent concentration, pH profile,Km(app),Vmax(app), productivity versus temperature, activity, and reaction rates were determined. Reaction rates of six lysyl dipeptides were compared. Crystalline trypsin was dansylated for studies by nanosecond fluorescence techniques to determine the effects of introducing high concentrations of organic solvents on the molecule. The results indicated that greater reaction rates were observed with dipeptides having more acidic carboxyl terminal groups. The data also indicated that greater reaction rates were observed in higher concentrations of solvents of lower dielectric constants. Nanosecond fluorescence spectroscopy of trypsin in high concentrations of a low dielectric constant solvent indicated major dehydration even though maximal enzyme‐activity was achieved under these condition

ISSN:0006-3592    

DOI:10.1002/bit.260180109

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

年代:1976

数据来源: WILEY

摘要:

AbstractLactose (β‐galactosidase) was attached to the inner surface of nylon tubing. Tubes of various lengths were used to bring about the hydrolysis ofo‐nitrophenyl‐β‐D‐galactoside and of lactose in skim milk. The results with the former substrate were analyzed in the light of a theoretical treatment of Kobayashi and Laidler (Biotechnol. Bioeng.,16, 99, 1974), with the conclusion that the reaction is intermediate between diffusion‐free and completely diffusion‐controlled behavior. The results with skim milk show that with a single 46 m tube and continuous circulation, 90% of the lactose is removed within 20 hr. A battery of ten such tubes, with single passage, at a flow rate of 2 cm/sec, would remove more than 99% of the lactose in l

ISSN:0006-3592    

DOI:10.1002/bit.260180110

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

年代:1976

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260180111

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

年代:1976

数据来源: WILEY