摘要:

AbstractThis paper is concerned with optimization of the operating mode of a fermentor. Combining the various modes of operation—batch, semibatch, and continuous—the operating pattern which maximizes the desired metabolic product in a single fermentor is determined by using Kelley's transformation method with Pontryagin's maximum principle. Kelley's transformation method is a device which avoids the singular situation which occurs when the usual procedure of selecting the optimal control function by the maximum principle breaks down. This is the case in the problem considered in this paper. For lysine fermentation, the best operating mode depends on the fermentor capacity and operating time. The results of this study are summarized thus: (i) when the operating time is “long enough,” optimal conditions require that continuous operation follows either semibatch and/or batch operation, and (ii) when the fermentor capacity becomes “large enough,” semibatch operation become

ISSN:0006-3592    

DOI:10.1002/bit.260200502

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

年代:1978

数据来源: WILEY

摘要:

AbstractA generalized mechanistic model for the enzymatic hydrolysis of cellulose is developed and expressed mathematically. The model is based on Michaelis–Menten‐type kinetics for concurrent random and endwise attack of the substrate involving end‐product inhibitions and three types of enzymes: an endo‐β;‐1,4‐glucanase, an exo‐β‐1,4‐glucanase, and β‐glucosidase. Basic parameters of the model which can explain synergistic and other effects observed experimentally are quantified and discussed. It is shown that cellulose degradation kinetics are expected to be strongly affected by the ratio of endo‐ to exocellulases in the reaction mixture as indicated by previous experimental data, and the substrate degree of polymerization, a factor not fully appreciated in previous studies, which appear to be overridingly important

ISSN:0006-3592    

DOI:10.1002/bit.260200503

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

年代:1978

数据来源: WILEY

摘要:

AbstractPullulanase was immobilized successfully by simple, inexpensive methods that may be useful for industrial application of this enzyme. A tannin–pullulanase(TP) complex was obtained by addition of tannic acid to the culture filtrate of thermophilicStreptomyces flavochromogenes. TP could be bound to TEAE–cellulose (TTCP). Immobilization in this manner took place with quantitative retention of activity. The immobilized enzymes were stable for more than six months. The optimum temperatures of the native enzyme and TP were both 50°C; that of TTCP was 45°C. In the presence of 5mMCa2+, the activity of TTCP was increased approximately twofold and the optimum temperature was raised to 50–60°C. Pullulanase was not significantly eluted from TP or TTCP by NaCl Solution (0

ISSN:0006-3592    

DOI:10.1002/bit.260200504

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe effect of waste characteristics on the removal of suspended solids and soluble phosphorus by alum, Al2(SO4)3·18H2O, was investigated in an activated sludge system with no cellular recycle. Under the conditions presently studied, it was found that sludge organisms grown in nitrogen‐ and phosphorus‐restricted media possess exceptionally large capsules and produce a higher surface electric charge per unit of fry weight. Chemical demand for separation of these capsulated cells is obviously higher than those solids cultivated under a well‐balanced nutrient condition. For phosphorus removal, the molar ratio of Al+3:P is a function of the initial concentrations of soluble phosphorus and suspended solids in solution. The relationship between percent phosphorus removal and the quantity of chemical coagulent used shows nonstoichiometric relationship; that is, the required molar ratio of Al+3:P is always greater than one and directly depends upon the content of suspended solids in the flocculated media. Moreover, the present study indicated that chemical separation of dispersed microorganisms occurred following phosphorus r

ISSN:0006-3592    

DOI:10.1002/bit.260200505

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

年代:1978

数据来源: WILEY

摘要:

AbstractOxygen absorption enhancement in a sodium sulfite solution was studied in the absence and presence of copper catalyst both for absorption across the liquid surface in a stirred cell and for absorption from individual bubbles rising through a turbulent liquid. The enhancement factor was determined from the ratio of oxygen and argon mass transfer coefficients, measured under identical experimental conditions in the same batch of liquid. It has been found that the oxygen absorption is not chemically enhanced, as long as the mass transfer coefficient,kL0, is high enough, i.e., higher than the value 1.4 × 10−4m sec−1for the sulfite solution we used. An analysis of our data as well as literature data indicates that the sulfite system is poorly suited for studies of the volumetric mass transfer coefficient of physical absorption (kL0a) in fermentors, inasmuch as oxygen absorption can be chemically enhanced while the degree of enhancement depends on the operating conditions of batch aeration, as well as on the concentration of trace impurities with catalytic effects upon the sulfite solution

ISSN:0006-3592    

DOI:10.1002/bit.260200506

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

年代:1978

数据来源: WILEY

摘要:

AbstractA novel fermentation device, the rotorfermentor, is described and some experimental results are presented on power requirements and oxygen mass transfer characteristics of the rotorfermentor. This fermentation device is designed to achieve high cell concentrations in batch and continuous cultures. Basically, the rotorfermentor consists of a rotating microporous membrane which is enclosed within a stationary fermentor vessel. The metabolic products in the broth are continuously removed by filtration through the rotating microporous membrane while the growing cells can be retained inside the fermentor. This dual function of cell growth and concentration with the simultaneous removal of metabolic products is the essential characteristic of the rotorfermentor.

ISSN:0006-3592    

DOI:10.1002/bit.260200507

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe kinetics of microbial growth and product formation are described as applied to the high cell concentration scheme of the rotorfermentor. A bench scale pilot plant was designed and built in order to demonstrate the operational feasibility of the rotorfermentor. The fermentation of glucose to ethanol bySaccharomyces cerevisiaeATCC 4126 was used. When the rotorfermentor was used with a glucose feed concentration of 104 g/liter almost 100% glucose utilization was obtained and the ethanol productivity rate was 27.3 g ethanol/liter hr which was found to be about 10 times greater than the ethanol productivity obtained from an ordinary continuous stirred tank (CST) Fermentor. The ethanol experimental results obtained from the rotorfermentor and an ordinary CST fermentor were used as a basis to assess the economic feasibility of the rotorfermentor. The economics of an industrial scale ordinary CST fermentor with and without cell recycle is compared with a rotorfermentor unit for the same ethanol production throughput. For the process conditions considered on this case, calculations showed that the rotorfermentor may replace both a CST fermentor and cell centrifuge resulting in lower capital equipment costs and lower power consumption requirements.

ISSN:0006-3592    

DOI:10.1002/bit.260200508

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe effect of soluble thiol reagents on the extractability of protein from yeast cells was studied. The incubation of yeast cells with dithiothreitol, 2‐mercaptoethanol, or monothioglycerol markedly stimulated the release of soluble carbohydrates into the medium. There was a concomitant improvement (over twofold) in the extractability of protein from the yeast cells. The thiol reagents activated the proteolytic enzymes of the yeast cells. Unless inactivated, these enzymes hydrolyze the extracted protei

ISSN:0006-3592    

DOI:10.1002/bit.260200509

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

年代:1978

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260200510

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

年代:1978

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260200511

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

年代:1978

数据来源: WILEY