摘要:

AbstractTwo photosynthetic algal cultures, oneChlorella vulgaris, and the other aChlorogoniumsp., were cultured under light limitations in chemostats. The effects of growth temperature on their energy yield and maintenance energy requirement were studied. It was observed that a lowering in temperature resulted in a lower maximum growth yield from the light energy,YG. This was attributed to two reasons. First, at low temperatures there was a change in the algal cell composition with more energy being expended to synthesize a higher biomass protein content. Secondly, at low temperatures, a cyanide‐resistant respiratory pathway became operative which led to a decrease in the number of ATP being generated. The maintenance energy coefficient was a function of temperature increasing with decreasing temperature. This might reflect energy wastage by the cell at low temperatures. The maximum specific growth rate dropped with decreasing temperature, and can be described by an Arrhenius type rate‐temperature model up to the optimal temperature for growth; i.e., activation energy remained const

ISSN:0006-3592    

DOI:10.1002/bit.260270502

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe effect of feast/famine growth conditions on activated sludge cultures indicates that nonfilamentous cultures can be selected by providing proper substrate gradients and extended periods of endogenous metablism. Reactor operating strategies providing intermittently high substrate concentrations result in cultures characterized by high peak substrate and oxygen uptake activities, rapid settling rates, and high resistance to starvation. Sludge settleability can be manipulated using controlled variations in growth environment with corresponding changes noted in sludge activity. In combination with the low net growth rates associated with activated sludge systems, feast/famine environments would logically convey a selection advantage to microbes capable of readily assimilating substrate materials and maintaining viability during extended starvation periods.

ISSN:0006-3592    

DOI:10.1002/bit.260270503

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

年代:1985

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260270504

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

年代:1985

数据来源: WILEY

摘要:

AbstractCellobiase was coupled to a dialdehyde dextran by reductive alkylation in the presence of sodium cyanoborohydride. The resulting conjugate, obtained without loss of enzymic activity, presents properties of thermoresistance largely superior to those of native enzyme: the rate of inactivation is reduced compared to that of native enzyme and its optimal temperature of activity is 70–75°C instead of 65°C. Finally the conjugate presents increased longevity when subjected to experiments of operational stability; its hydrolytic activity is maintained at 60°C in a 10% (w/v) cellobiose solution for more than 100 h whereas the native enzyme is inactivated after 45 h. The cellobiase–dextran conjugate was immobilized by covalent coupling on aminated silica by reductive alkylation in the presence of NaBH3CN. The characteristics of thermoresistance of this stabilized and immobilized conjugate were studied and compared to those of a preparation of native cellobiase immobilized on a silica support activated with glutaraldehyde. Analysis of the thermoresistance of these two cellobiase preparations clearly shows that immobilization has maintained and even enhanced their properties. In particular, the operational stability, measured at 68°C on 10% (w/v) cellobiose shows an increased longevity of the stabilized and immobilized enzyme for 120 h compared to 60 h for the native immobilized enzyme. Two successive incubations of these cellobiase derivatives show that it is possible to obtain 2.5 times more glucose with the stabilized‐immobilized enzyme than with the immobilized preparation. The procedure described above enables us to prepare a thermostabilized immobilized c

ISSN:0006-3592    

DOI:10.1002/bit.260270505

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe graft copolymer, poly(maleic anhydride/styrene)‐co‐polyethylene was prepared. The copolymer immobilized bovine serum albumin (BSA), but the amount coupled appeared to be effected by the amount of styrene in the graft copolymer, temperature, and pH of the coupling medium. Competition existed between hydrolysis of the grafted anhydride groups and the protein. A graft copolymer with 66% add‐on immobilized 4.5 mg/glucose oxidase/g copolymer, 4.6 mg alkaline phosphates/g copolymer and 0.2 mg cell ofBacillus stearothermophilus/g copolymer. A number of copolymers containing poly(maleic anhydride/vinyl acetate)–co‐polyethylene were prepared to cover a range of grafting levels. These immobilized larger quantities of BSA, alkaline phosphatase, and cells ofB. stearothermophilusthan did the styrene graft copolymer. The copolymer was also hydrolyzed to release the hydroxyl group from the poly(vinyl acetate) component of the grafted chains. Usingp‐benzoquinone as the “activating agent,” the copolymer coupled to BSA and to acid phosphatase. Usingp‐toluene‐sulfonyl chloride, the copolymer was very effective in i

ISSN:0006-3592    

DOI:10.1002/bit.260270506

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

年代:1985

数据来源: WILEY

摘要:

AbstractFor the cultivation of mammalian cells on microcarriers a minimum inoculum concentration is required to initiate cell attachment and subsequent cell growth. A critical cell number model has been proposed to elucidate the mechanism of the inoculum requirement. In this model it was hypothesized that after inoculation a critical number of cells per microcarrier is required for normal growth to occur; failure to acquire enough cells will impede cell growth. This critical cell number model was expressed mathematically and used to simulate cell distribution and growth on microcarriers under different cultivation conditions. By comparing the simulated growth kinetics with the experimental results, the actual critical cell number per microcarrier was identified. The critical number could be reduced by employing an improved medium for the cultivation.

ISSN:0006-3592    

DOI:10.1002/bit.260270507

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

年代:1985

数据来源: WILEY

摘要:

AbstractA regenerating reaction combined with the use of native malate dehydrogenase, native diaphorase, methylviologen, NAD, oxalacetic acid as the substrate and lipoamide as a stabilizer was carried out in the presence of electrolysis. Consequently, malic acid was efficiently produced from oxalacetic acid in the regenerating reaction. A glassy carbon bead electrode was used as a cathode. Twenty four milliamperes were passed at a rotation speed of 500 rpm, 29.8 ± 0.3°C and −1.0 V. It was found that lipoamide has a stabilizing effect on malate dehydrogenase and diaphorase. Low concentration (50 μM) of NAD was also effective for the stabilization of malate dehydrogenase. NADH regeneration activity based on malic acid production rate was 4.7 U/mg of the enzyme protein of the commercial diaphorase preparation. The current efficiency was more than 74%, compared with the theoretical yield, in the presence of enough oxalacetic

ISSN:0006-3592    

DOI:10.1002/bit.260270508

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

年代:1985

数据来源: WILEY

摘要:

AbstractWe describe the use of affinity chromatography for separation of cell populations that do not differ significantly with respect to gross physical properties such as size, density, or charge. Cell affinity chromatography exploits differences in cell surface macromolecules by passage of mixtures of cell populations through a column containing beads to which are attached chemical ligands with specific binding affinity for particular cell surface receptors. In this article we focus on the application of this concept to separation of mature T lymphocytes from peripheral blood. This serves as a model for the separation of these cells from bone marrow in order to prevent graft‐vs.‐host disease in bone marrow transplantation. However, the concept of cell affinity chromatography should find more general widespread utility in a variety of biotechnological applications. Thus, we introduce a simple theoretical framework which is necessary in order to understand the results that might be expected in any given situation. Finally, we use this theory to provide a tentative explanation for experimental observation of the effects of temperature and flowrate on the degree of separation achieved for our current pplicat

ISSN:0006-3592    

DOI:10.1002/bit.260270509

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

年代:1985

数据来源: WILEY

摘要:

AbstractImmobilized growing cells ofZymomonas mobiliswere found to ferment rapidly and efficiently media containing 100 g/L fructose in a continuous reactor. A volumetric ethanol productivity of 94.8 g/L h was achieved at a substrate conversion of 75.5%. With 97% conversion of substrate the productivity was 28.4 g/L h. At fructose concentrations of 150 and 200 g/L substrate and product inhibitions limited the performance of the reactor. Ethanol production was constant over a period of 55 days.

ISSN:0006-3592    

DOI:10.1002/bit.260270510

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe reaction parameters for preparation of Cibacron Blue F3G‐A polyethylene glycol have been studied, including temperature, concentration of reactants, and addition of neutral salt (Na2SO4) as well as ethanol. The yield of dypolymer is strongly dependent on temperature and time of reaction. Preparation in large scale has been done under optimal conditions binding more than 30% of the dye to polyethylene glycol in a low‐cost procedure. The effectiveness of this dye‐polymer for use in liquid–liquid extraction of enzymes is demonstrated by partition of glucose 6‐phosphate dehydrogenase and phosphofructokinase when an extract of baker's yeast is included in a dextran–polyethylene glycol–water two

ISSN:0006-3592    

DOI:10.1002/bit.260270511

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

年代:1985

数据来源: WILEY