摘要:

AbstractLiquid membrane bilayers, generated by bacteriorhodopsin on a supporting membrane, exhibit photo osmosis. The phenomenon has been shown to be a consequence of light‐induced electrical potential differences which develop across the liquid membrane bilayer due to the light‐driven proton pumping action of bacteriorhodopsin. The variations of photo osmotic velocity with wavelength, intensity of light, and proton acceptor concentrations has been stud

ISSN:0006-3592    

DOI:10.1002/bit.260310602

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

年代:1988

数据来源: WILEY

摘要:

AbstractA continuous process has been devised and tested for purification of a crude trypsin preparation from pig pancreas. The development was based on the principles of affinity chromatography and Ultrafiltration. Trypsin was selectively attracted by a water‐soluble high molecular weight (>100,000) polymer, bearing a potent and specific trypsin inhibitor, m‐aminobenzamidine. The trypsin‐macroligand complex was then retained by using an appropriate Ultrafiltration membrane, while impurities could pass through. The bound trypsin was eluted by either arginine or benzamidine. The process also featured provision for recirculation of the eluant as well as the macroligand. It was demonstrated that this purification process could purify trypsin from the crude preparation with a yield of 77%, contaminated with only 3% of impurities. For the first time, a serious attempt has been made toward continuous purification of enzymes by the affinity Ultrafiltration technique. Besides a substantial increase in productivity, the affinity polymer could be easily reconditioned and expected to possess a long operative life. Such characteristics undoubtedly will play an important role in reducing the cost of trypsin purific

ISSN:0006-3592    

DOI:10.1002/bit.260310603

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

年代:1988

数据来源: WILEY

摘要:

AbstractA novel biomethanation process configuration is described which uses improved biocatalysts to enhance the productivity and stability of waste biomethanation systems. The design facilitates the maintenance of acetogenic and methanogenic bacteria under optimum substrate concentrations far above theirKsvalues in a two‐stage biomethanation system with closed loop reactors. Volatile fatty acid anions (VFA anions) are provided as substrates for the methanogenic stage by using an anion exchange unit coupled to the acidogenic stage. The slow growing and sensitive acetogenic and methanogenic bacteria are protected from oxygen, cationic pollutants, toxins, and microbial contamination by use of the substrate shuttle process. Due to the closed loop process configuration, washout of the ecoengineered biocatalysts is excluded. The modular system configuration allows industrial mass production of the system components. The new biomethanation process enhances both the BTU content of the gas and the methane production over state‐of‐the‐art anaerobic digestor bioreactor c

ISSN:0006-3592    

DOI:10.1002/bit.260310604

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe unbound bilirubin concentration and the enzymatic rate of bilirubin degradation by bilirubin oxidase in bilirubin‐serum albumin solutions have been investigated experimentally and theoretically. A stoichiometric bilirubin‐serum albumin binding analysis shows that the unbound bilirubin concentration depends only on the molar ratio of the total bilirubin concentration to the total serum albumin concentration. From the theoretical analysis and the measured unbound bilirubin concentrations, serum albumin may be modelled as a molecule having two binding sites, primary and secondary, with stoichiometric equilibrium constants ofK1= 6 × 107M−1andK2= 4.5 × 106M−1, respectively. The rate of total bilirubin degradation in bilirubin‐serum albumin mixtures is zero order. An immobilized bilirubin oxidase reactor model, which shows good agreement with experimental bilirubin conversions, is presented. At a flow rate of 1 mL/min with a 8‐mL reactor volume, a 50% bilirubin conversion per pass was observed with an inlet bilirubin concentration of 350μMand a serum albumin concentr

ISSN:0006-3592    

DOI:10.1002/bit.260310605

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

年代:1988

数据来源: WILEY

摘要:

AbstractA solution of bovine serum albumin (BSA) is repeatedly injected into a column packed with highly porous and hydrophobic polymer resins at appropriate intervals. The injected BSA is thoroughly retained in the column for 10 injections and, afterwards, starts to be eluted from the column gradually. Taking into consideration the restricting effect of already bound BSA upon the diffusion of newly injected BSA into the pores of the polymer resins, we can interpret the BSA elution profile from columns packed with polymer resin of various pore sizes and porosities. The effects of the binding rate constant and BSA concentration upon the elution profiles of BSA are also analyzed. Formyl groups are introduced into the polymers as a binding site with proteins, and the elution profiles of BSA from the column packed with the formylated resin are also analyzed.

ISSN:0006-3592    

DOI:10.1002/bit.260310606

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

年代:1988

数据来源: WILEY

摘要:

AbstractA reactor, using the enzymatic electrocatalysis scheme, was developed on a laboratory preparative scale for the catalytic oxidation of glucose into gluconic acid. Glucose oxidase was directly immobilized on the surface of a carbon felt electrode and a solution of glucose and benzo‐quinone passed through the electrode in order to regenerate the electron acceptor. The reactor was able to produce continuously 1.5 g gluconate/h with a catalytic current of 0.4 A. This gave a high productivity ca. 100 g/h/L reactor. A one‐dimensional model was developed which demonstrated the efficiency of coupling between enzymatic and electrochemical reactions due to the proximity of the two reaction sites. For example the catalytic current was practically independent of mass transfer parameters. The operational stability of immobilized glucose oxidase was increased 50 times at least when electroregenerated benzoquinone was used as oxidant instead of oxy

ISSN:0006-3592    

DOI:10.1002/bit.260310607

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

年代:1988

数据来源: WILEY

摘要:

AbstractNaphthalene‐2‐sulfonate was degraded by submerse growing Pseudomonads in a chemostat culture. The kinetic parameters for the Monod equation, including Pirts maintenance energy, were calculated from these experiments regarding naphthalene‐2‐sulfonate as substrate and oxygene as cosubstrate. By immobilizing the bacteria on sand particles, the degradation of naphthalene‐2‐sulfonate was carried out in a specialy designed three‐phase airlift‐loop reactor in a completely fluidized state. From these experiments, the influence of biofilm diffusion limitation on reaction kinetics and criteria for stable biofilm formation on sand particle

ISSN:0006-3592    

DOI:10.1002/bit.260310608

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

年代:1988

数据来源: WILEY

摘要:

AbstractIn production‐scale bioreactors microorganisms are exposed to a continually changing environment. This may cause loss of viability, reduction of the yield of biomass or desired metabolites, and an increase in the formation of by‐products. In fed‐batch production of baker's yeast, profiles may occur in substrate and oxygen concentrations and in pH. This article deals with the influence of a periodically changing oxygen concentration on the growth of baker's yeast in a continuous culture. Also, influences on the production of ethanol, glycerol, acetic acid, and on the composition of the cells were investigated. It was found that relatively fast fluctuations between oxygen‐unlimited and oxygen‐limited conditions with a frequency of 1 or 2 min had a distinct influence on the biomass and metabolite production. However, RNA, protein, and carbohydrate contents measured in cells exposed to fluctuations differed little from those in cells from an oxygen‐unlimited or an oxygen‐limited culture. The respiration and fermentation capacities of cells exposed to fluctuations can be larger than the capacities of cells grown under oxygen‐unlim

ISSN:0006-3592    

DOI:10.1002/bit.260310609

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

年代:1988

数据来源: WILEY

摘要:

AbstractA reactor configuration consisting of two reactors with an exchange flow was used for the experimental simulation of large‐scale conditions. The influence of fluctuations in oxygen concentration on the growth and metabolite production of baker's yeast was investigated by sparging one fermentor with air and one with nitrogen gas. It was found that the biomass yield decreased and the metabolite formation increased with rising circulation time (longer oxygen‐unlimited and oxygen‐limited periods). Not only was the performance of the oxygen‐limited fermentor characterised by (partly) reductive metabolism, but that of the oxygen‐unlimited fermentor as well. The results of the experiments in this reactor system were compared with those from the experiments carried out in a one‐fermentor system with periodically changing oxygen concentrations. The formation of acetic acid, which is characteristic for transient states, showed a distinct difference between the two reac

ISSN:0006-3592    

DOI:10.1002/bit.260310610

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

年代:1988

数据来源: WILEY

摘要:

AbstractThe concepts of artificial intelligence have been applied for the development of a software system for metabolic pathway synthesis (MPS). An easily expandable data base system for storing enzyme and substance descriptions is used by a search algorithm for the identification of possible ways to interconvert carbon‐carrying metabolites. A versatile screening capability permits the user to identify all pathways which contain or exclude any combination of enzymes, substrates, and/or products. Information provided by MPS can be used to predict on a qualitative basis the effects of adding or deleting enzymatic activities to or from the cellular environment, to classify pathways with respect to cellular objectives, and to extract information about metabolic regulation. MPS can be used subsequently to aid the identification of appropriate genotypes or genetic modifications that will redirect metabolism towards amplified production of desirable bioproducts. Two examples illustrating the capabilities of MPS are presented. In the first example, which considers the conversion of glucose 6‐phosphate to pyruvate, MPS synthesized the classical catabolic pathways (EMP, pentose phosphate and ED) along with possible variations. A route for the biosynthesis ofL‐alanine that does not incorporate the enzymealanine aminotransferasewas revealed by MPS during synthesis of alternative pathways which produceL‐alanine from p

ISSN:0006-3592    

DOI:10.1002/bit.260310611

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

年代:1988

数据来源: WILEY