摘要:

AbstractThe influence of temperature, illumination, hormonal levels (2,4‐D and kinetin), carbon to nitrogen ratios, antibiotics, and precursor feeding on phenolics production byNicotiana tabacum(tobacco) was studied. This plant cell system was chosen as a model system to learn more about secondary product formation in plant cell tissue cultures. This is the first study to manipulate all of these environmental parameters with a single plant cell system. The most striking results were with 2,4‐D manipulation. The removal of 2,4‐D resulted in significant phenolics production during the stationary phase, while normal levels strongly suppressed phenolics production during the stationary phase. The addition of phenylalanine stimulated phenolics production per gram of cells but strongly inhibited g

ISSN:0006-3592    

DOI:10.1002/bit.260260202

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

年代:1984

数据来源: WILEY

摘要:

AbstractA kinetic model was devised for the hydrolysis and synthesis of maltose and isomaltose by two glucoamylases fromRhizopus niveusandAspergillus niger, and the validity of the model was verified experimentally at 313 K and pH 5.0. For both enzymes, the formations of maltose and isomaltose from glucose were parallel reversible reactions, and glucosyl transfer between maltose and isomaltose was not observed. The enzymes catalyzed rapid hydrolysis and synthesis of maltose. Isomaltose was hydrolyzed and synthesized more slowly, but the level produced from glucose was much higher than that of maltose. These hydrolysis and condensation reactions were expressed well by the model.

ISSN:0006-3592    

DOI:10.1002/bit.260260203

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

年代:1984

数据来源: WILEY

摘要:

AbstractPichia polymorphahas inulinase activity and could be used for the production of fructose syrup from inulin. The application of immobilizedP. polymorphawhole cells for the continuous hydrolysis of inulin is, however, limited since the biosynthesis of this enzyme system is repressed by the reaction products, dextrose and fructose. A derepressed mutant hyperproducer of inulinase was isolated after treatment with EMS followed by a selection step with deoxyglucose.

ISSN:0006-3592    

DOI:10.1002/bit.260260204

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe technique of cell immobilization using porous support particles (biomass support particles) has been successfully applied to yeast cells. Two reactor configurations exploiting the use of these particles have been developed and assessed for use in aseptic yeast fermentations. A liquid‐fluidized bed fermenter has been devised for use with particles denser than the fermentation liquor whilst a gas‐stirred circulating bed fermenter proved suitable for particles of essentially neutral buoyancy. Both systems have been operated successfully for extended periods of continuous operation. The utilization of biomass support particle technology in such reactors provides a practical and robust system for immobilized cell reactors. This technology offers significant opportunities for further developm

ISSN:0006-3592    

DOI:10.1002/bit.260260205

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

年代:1984

数据来源: WILEY

摘要:

AbstractBiomass autoflocculation in outdoor algal cultures was found to be associated with increases of culture pH levels, due to CO2consumption by the algal photosynthetic activity. Under these alkaline conditions, some medium chemical ions precipitated together with the algal biomass. The chemical substances involved with the process and its dependence on pH value were studied by simulation of autoflocculation in laboratory experiments. Proper concentrations of calcium and orthophosphate ions in the medium are important for autoflocculation and, in order to attain it within the pH range 8.5–9.0, the culture should contain 0.1mM–0.2mMorthophosphate and 1.5mM–2.5mMcalcium prior to raising the pH level. Calcium phosphate precipitates are considered as the flocculating agent which reacts with the negatively charged surface of the algae and promotes aggregation and floccul

ISSN:0006-3592    

DOI:10.1002/bit.260260206

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

年代:1984

数据来源: WILEY

摘要:

AbstractButanediol production byAerobacter aerogenesNRRL B199 grown on glucose requires an optimal rate of aeration for the obtention of butanediol 2, 3. In the absence of air,Aerobacter aerogenesNRRL B199 growth and production are weak. Agitation‐aeration is necessary for producing the biomass, but an excess of oxygen proves to be toxic with regard to metabolite production. Oxygen is a limiting substrate with regard to growth and an inhibitor with regard to the specific metabolite productivity. This observation is discussed from a kinetic stand point and in relation to the search for the optimum oxygen transfer coefficient (KLa), which is found to be in the range of 50–100h−1. It has also been observed thatKLaincreases during the fermentation cycle. The initial substrate concentration effects the yield production of biomass and butanediol production. Low yields of butanediol are obtained at low initial sugar concentrations, but good yields of butanediol are obtained (0.45 g/g) at high concentrations of glucose (195 g/L). Carbon substrates and butanediol are inhibitors of cell growth while butanediol is not quite an inhibitor of the specific rate of butanediol production for the range of butanediol of 0–

ISSN:0006-3592    

DOI:10.1002/bit.260260207

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

年代:1984

数据来源: WILEY

摘要:

AbstractExperimental investigation is by far the most effective approach for studying the behavior of physical systems. However, an enzymatic solubilization of vegetable protein is a complex combination of intrinsic problems, of which many are not easily adaptable to experimental investigation. Experimental designs to study enzyme vegetable protein reactions yield data which describe the extramembraneous activity of the immobilized enzyme. In a continuous recycle immobilized enzyme reactor, the microenvironment concentration of the substrate or product in the membrane phase, or the concentrations along the reactor axial length in the bulk phase are not discernible to the experimenter. However, the knowledge of such concentration profiles is important in weighing the significance of such factors as intermembrane diffusion, enzyme loading, wet membrane size, and the mode of operation of the reactor. The simulation of mathematical models, which describe the physical system within the constraints imposed, yields information which is vital to the understanding of the process occurring in the reactor. The kinetics and diffusion of an immobilized thermophilicPenicillium dupontienzyme at pH 3.4–3.7 and 50°C was modeled mathematically. The kinetic parameters were evaluated by fitting a model to experimental data using nonlinear regression analysis. Simulation profiles of the effects of reactor geometry, substrate concentration, membrane thickness, and enzyme leading on the hydrolysis rate are presented. From the profiles generated by the mathematical model, the best operational reactor strategy is recommend

ISSN:0006-3592    

DOI:10.1002/bit.260260208

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

年代:1984

数据来源: WILEY

摘要:

AbstractAn enzyme designated as lactate oxidase was purified fromAcetobacter peroxydansby using the partition methods of separation. A DE‐52 cellulose column was used for the primary purification of lactate oxidase, and the purified enzyme was covalently bound to a porous cellulose bead matrix in which benzoquinone was used as the coupling reagent. The physicochemical properties of the native and immobilized enzymes were determined including molecular weight, cofactor requirements, and optimal reaction conditions. Lactate oxidase was shown not to be subject to product inhibition, and to require Mg2+as a metal cofactor. Analysis of an immobilized lactate oxidase packed‐bed reactor indicated that this system may not be subject to internal diffusional limitations. Molecular oxygen appeared to be a cosubstrate of the enzyme, and a reaction mechanism was postulated to predict the kinetic behavior of the immobilized reactor system. Applications of the immobilized lactate oxidase reactor for the pulse‐flow analysis of lactic acid in whole milk and in a yeast fermentation system were consi

ISSN:0006-3592    

DOI:10.1002/bit.260260209

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

年代:1984

数据来源: WILEY

摘要:

AbstractA stoichiometric equation has been derived which describes the interrelations among the various products and biomass in fermentations of butyric acid bacteria. The derivation of the equation is based on an assumed ATP yield, two biological regularities, and the biochemistry of product formation of the fermentations. The equation obeys the constraints imposed on growth and product formation by thermodynamics and the biochemical topology. The validity of the equation is tested using a variety of fermentation data from the literature. The uses, improvements, limitations, and extensions of the equation are also discussed in detail. For example, the fermentation equation is used to calculate the maximal possible yields of the main fermentation products.

ISSN:0006-3592    

DOI:10.1002/bit.260260210

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

年代:1984

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260260211

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

年代:1984

数据来源: WILEY