摘要:

AbstractNitrifying characteristics were compared for an extended aeration (total cell recycle) process and one employing an engineering modification of the process utilizing a “hydrolytic assist” to aid biological autodigestion. Laboratory pilot plants were run over a period of years, and it was found that the recently recommended “hydrolytic assist” did not militate against production of a highly nitrified effluent. Under this mode of operation, the effluent was as nitrified as the effluent from the normal extended aeration process. It was also found that the modified process rapidly recovered its nitrifying capability after a period of deprivation of excess ammonia nitrogen. Throughout the period of operation, substrate removal efficiency remain

ISSN:0006-3592    

DOI:10.1002/bit.260160103

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

年代:1974

数据来源: WILEY

摘要:

AbstractAn apparatus is described which is designed for preparative freeze concentration experiments by the technique of normal freezing. It has a capacity of approximately 22 liters distributed over twelve vessels. The influence of various geometrical and chemical parameters such as stirring speed, crystallization rate, and sample composition on the normal freezing of protein solutions are discussed. For dilute protein solutions (<0.1%) the concentration factor generally was 8‐ to 10‐fold with recoveries of 90–100 percent. With higher protein concentrations and at ionic strengths higher than approximately 0.05, the recovery was decreased. No loss of activity was detected when concentrating enzyme solu

ISSN:0006-3592    

DOI:10.1002/bit.260160104

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe growth of a mixed methane‐utilizing culture in a continuous flow fermenter has been studied under both methane and oxygen limitation. Small additions of methanol have been shown to inhibit the methane‐utilizing moiety in the culture and it has been shown that theHyphomicrobiumsp. in the mixed culture removes any inhibitory methanol. The interaction between the methane‐utilizingPseudomonassp., and theHyphomicrobiumsp. has been explained and a model of the continuous mixed culture under oxygen limitation has been formulated. Qualitative predictions of transient phenomena by the model have been verified experimen

ISSN:0006-3592    

DOI:10.1002/bit.260160105

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

年代:1974

数据来源: WILEY

摘要:

AbstractPolysaccharide was synthesized byAureobasidium pullulans(orPullularia pullulans) 2552 in a sucrose medium. The field apparent viscosity of the culture medium from shake flask experiments rose to 24,500 cP and then dropped toward its initial value as the fermentation progressed. The magnitude of the maximum apparent viscosity depended on the initial pH of the fermentation broth. The inoculum age influenced the cultivation period before which the maximum viscosity was reached. Rheograms of the fermentation broths showed a change in viscosity behavior from Newtonian to pseudoplastic, and then toward Newtonian characteristics during the fermentation. The calculated non‐Newtonian index was found to be a sensitive factor for the indication of the non‐Newtonian behavior. Such behavior could not be detected from rheograms. Viscosity profiles of polysaccharide isolated from various stages of the fermentation showed a change from Newtonian to pseudoplastic behavior depending on the concentration (0–2%) of polysacch

ISSN:0006-3592    

DOI:10.1002/bit.260160106

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

年代:1974

数据来源: WILEY

摘要:

AbstractA theoretical treatment has been worked out for the kinetics of solid‐supported enzyme systems, with diffusive and electrostatic effects taken into account. A utilization factor, defined as the ratio of the actual reaction rate to the rate of substrate consumption in the outer solution, is defined, and equations to evaluate the utilization factor are given for five kinetic conditions: (a) Michaelis‐Menten behavior, (b) substrate inhibition, (c) product inhibition (competitive), (d) product inhibition (noncompetitive), and (e) product inhibition (anticompetitive). When the solid‐supported enzymes obey a Michaelis‐Menten relationship, an equation for the apparent Michaelis constant is given and a criterion for insignificant diffusion effects is shown. A substrate‐inhibited enzyme reaction may display multiple steady‐state behavior, and a criterion for uniqueness is presented. In the case of product‐inhibited enzyme reactions, the utilization factor is always less than that which corresponds to a Michaelis‐Menten relationship. Equations to evaluate the apparent Michaelis and inhibition cons

ISSN:0006-3592    

DOI:10.1002/bit.260160107

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

年代:1974

数据来源: WILEY

摘要:

AbstractA theoretical treatment is given of the kinetics of reactions catalyzed by enzymes attached to the inner surface of a tube, through which the substrate solution passes. A utilization factor, the ratio of the actual reaction rate to that in the absence of diffusional effects, is defined. A numerical procedure is proposed and numerical and approximate solutions for the utilization factor are given for five kinetic conditions: (a) Michaelis‐Menten behavior, (b) substrate inhibition, (c) product inhibition (competitive), (d) product, inhibition (non‐competitive), and (e) product inhibition (anticompetitive). When the enzyme chemically attached to a tube obeys a Michaelis‐Menten relationship, criteria for insignificant and significant diffusional effects are pro

ISSN:0006-3592    

DOI:10.1002/bit.260160108

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

年代:1974

数据来源: WILEY

摘要:

AbstractL‐Asparaginase has been attached by chemical means to the inner surface of nylon tubing. An experimental study has been carried out of the flow kinetics for such a system, asparagine solutions at various concentrations being passed through two lengths of tubing at various flow rates. Measurements were made of the concentration of the product ammonia at the tube exit, and of the rate of formation of ammonia, under the various conditions. Apparent Michaelis constants,Km(app), were some three orders of magnitude higher than theKmfor the enzyme in free solution (∼13 × 10−6JM). The results were analyzed with respect to the theoretical treatment described in the preceding paper (Kobayashi and Laidler), three different methods being employed. It is concluded that at lower substrate concentrations and flow rates the reactions are largely diffusion‐controlled, the enhancedKm(app) values being largely if not entirely due to the diffusion control; ionic strength studies showed electrostatic repulsion effects to be unimportant. At high concentrations and high flow rates (when the diffusion layer is of negligible thickness) the diffusional effects are minimized, andKm(app) approaches the trueKmvalue for the immobilize

ISSN:0006-3592    

DOI:10.1002/bit.260160109

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

年代:1974

数据来源: WILEY

摘要:

AbstractAn α‐galactosidase which will hydrolyze the oligosaccharides melibiose, raffinose, and stachyose has been immobilized on nylon microfibrils suitable for use in large flow‐through reactors. This catalyst system is stable for many months, both under use and storage conditions. The immobilized enzyme behaves similarly to the enzyme in solution, characteristically exhibiting both product and substrate inhibition. The catalyst is preparedin situand a large, 8‐liter reactor has been made. The catalyst has been used to reduce the raffinose concentration in beet sugar mo

ISSN:0006-3592    

DOI:10.1002/bit.260160110

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

年代:1974

数据来源: WILEY

摘要:

AbstractHeLa S3 cells in suspension culture are resynchronized in each successive generation by exposure to 0.25mMthymidine. The resynchronization approach appears to be superior to single‐ and double‐block techniques because the period of effective inhibition of DNA synthesis is significantly shortened. Gram quantities of highly synchronous viable cells have been produced on a daily ba

ISSN:0006-3592    

DOI:10.1002/bit.260160111

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

年代:1974

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260160102

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

年代:1974

数据来源: WILEY