摘要:

AbstractInteraction of a number of arbitrarily chosen proteins with Triton X‐100‐substituted Sepharose 4B has been investigated. Of the proteins examined, bovine serum albumin, hemoglobin, glutamate dehydrogenase, and pepsin were found immobilized on the adsorbent. Binding of these proteins occurred irrespective of pH and NaCl concentration. Cytochrome c, used as a model protein, was totally immobilized only at low pH. Adsorption of glutamate dehydrogenase and pepsin took place with retention of their catalytic activities. Moreover, glutamate dehydrogenase used as a model allosteric enzyme, was found to retain its native properties upon binding to the adsorbent in the forms of suspension or column. Results are discussed in terms of specific interactions involving the hydrophobic region of Triton X‐100 and the apolar patches or crevices present on the surface of protein molecules. Possible potential of the matrix as a method for preparation of biologically active immobilized proteins and its application in continuous operations are also disc

ISSN:0006-3592    

DOI:10.1002/bit.260260602

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

年代:1984

数据来源: WILEY

摘要:

AbstractDuring the oxygen limiting growth ofKlebsiella oxytoca, the xylose metabolism may be considered as consisting of three components: conversion to 2,3‐butanediol by “fermentation,” oxidation to carbon dioxide by respiration, and assimilation to cell mass. The amount of energy required for the assimilation of cell mass is assumed to determine the extent to which the two energy producing reactions occur. The activity of each energy producing pathway is also determined by the availability of oxygen and by the energy yield of each pathway. These relationships can be quantified by equating the ATP required for growth and maintenance to the ATP produced by the energy producing reactions. The resulting equation for butanediol production appears similar to the Luedeking and Piret model where the parameters α and β are related to the maximum cell yield from ATP and the maintenance energy requirement. These parameters were estimated from 14 batch fermentations, and the resulting simulation was used to describe the effects of the oxygen transfer rate and the initial xylose concentration on the yields and rates of the 2,3‐butanediol fer

ISSN:0006-3592    

DOI:10.1002/bit.260260603

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

年代:1984

数据来源: WILEY

摘要:

AbstractEnzymatic properties ofAlcaligenes faecaliscells immobilized in polyacrylamide were characterized and compared with those reported for the extracted enzyme, and with those measured for free cells. Many of the properties reflected those of the extracted enzyme rather than those measured in the free whole cells prior to immobilization, suggesting cell disruption during immobilization. These properties included the pH activity profile, a slightly broader pH stability profile, and the activation energy. Electron micrographs showed evidence of cell debris among the polymer matrix. The immobilized cells were not viable, and did not consume glucose. Thermal stability was less after immobilization with a half‐life of 16 h at 45°C, and 3.5 h at 50°C. The immobilized preparation was more stable when stored lyophilized rather than in buffer, losing 23 and 52% activity, respectively, after six months. The enzyme was irreversibly inhibited by both acetate and citrate buffers. If the immobilized enzyme is to be used in conjunction with cellulases fromTrichoderma reeseifor cellulase saccharification, the optimal conditions would be pH 5.5 and 45°C in a buffer containing no carboxylic acid gr

ISSN:0006-3592    

DOI:10.1002/bit.260260604

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

年代:1984

数据来源: WILEY

摘要:

AbstractStreptomyces flavogriseusCMCase and Avicelase were very stable at 30°C but not at 40°C or higher. β‐Glucosidase was less stable at all temperatures tested. Stabilities were similar at pH values between 5.5 and 7, the optimal range for enzyme activity. Cellulose solubilizing activity was reduced by 40% at a cellobiose concentration of 150mMbut glucose inhibited activity by only 10% at this concentration. β‐Glucosidase was inhibited by 40% at a glucose concentration of 10mM(ten times the substrate concentration). Relatively diluteS. flavogriseuscellulase extensively hydrolysed acid‐swollen cellulose at concentrations as high as 10%. More highly crystalline forms of cellulose were more resistant

ISSN:0006-3592    

DOI:10.1002/bit.260260605

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

年代:1984

数据来源: WILEY

摘要:

AbstractCyclomaltodextrin glucanotransferase [1,4‐α‐D‐glucan‐4‐α‐D‐(1,4‐α‐D‐glucano)–transferase (cyclizing), E.C.−2.4.1.19] of an alkalophilicBacillussp. No. 38‐2 (ATCC 21783), which contains three types of enzymes (acid, neutral, and alkaline enzymes), was immobilized on synthetic adsorption resin. No distinguishing changes in pH or thermal stabilities of enzyme were observed due to the immobilization. Since acid–enzyme activity had disappeared, the optimum pH of immobilized enzyme was 9.0. Optimum temperature for the enzyme activity changed from 50 to 55°C. The enzyme converted starch to cyclodextrins without significant loss of activity under the conditions of continuous reaction for about two weeks by using the column system (60°C at pH 8.0). About 63% of soluble starch solution [4% (w/v)] was changed to

ISSN:0006-3592    

DOI:10.1002/bit.260260606

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

年代:1984

数据来源: WILEY

摘要:

AbstractA new enzymatic method for the removal of phenols from industrial aqueous effluents has been developed. The method uses the enzyme polyphenol oxidase which oxidizes phenols to the correspondingo‐quinones; the latter then undergo a nonenzymatic polymerization to form water‐insoluble aggregates. Therefore, the enzyme in effectprecipitatesphenols from water. Polyphenol oxidase has been found to nearly completely dephenolize solutions of phenol in the concentration range from 0.01 to 1.0 g/L. The enzymatic treatment is effective over a wide range of pH and temperature; a crude preparation of polyphenol oxidase (mushroom extract) is as effective as a purified, commercially obtained version. In addition to phenol itself, polyphenol oxidase is capable of precipitating from water a number of substituted phenols (cresols, chlorophenols, naphthol, etc.). Also, even pollutants which are unreactive towards polyphenol oxidase can be enzymatically coprecipitated with phenol. The polyphenol oxidase treatment has been successfully used to dephenolize two different real industrial waste‐water samples, from a plant producing triarylphosphates and from a coke plant. The advantage of the polyphenol oxidase dephenolization over the peroxidase‐catalyzed one previously elaborated by the authors is that the former enzyme uses molecular oxygen instead of costly hydrogen peroxide (used by peroxidase) as an

ISSN:0006-3592    

DOI:10.1002/bit.260260607

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

年代:1984

数据来源: WILEY

摘要:

AbstractA dynamic mathematical model has been developed to describe microbial desulfurization of coal byThiobacillus ferrooxidans. The model considers adsorption and desorption of cells on coal particles and microbial oxidation of pyritic sulfur on particle surfaces. The influence of certain parameters, such as microbial growth rate constants, adsorption‐descrption constants, pulp density, coal particle size, initial cell and solid phase substrate concentration on the maximum rate of pyritic sulfur removal, have been elucidated. The maximum rate of pyritic sulfur removal was strongly dependent upon the number of attached cells per coal particle. At sufficiently high initial cell concentrations, the surfaces of coal particles are nearly saturated by the cells and the maximum leaching rate is limited either by total external surface area of coal particles or by the concentration of pyritic sulfur in the coal phase. The maximum volumetric rate of pyritic sulfur removal (mg S/h cm3mixture) increases with the pulp density of coal and reaches a saturation level at high pulp densities (e.g. 45%). The maximum rate also increases with decreasing particle diameter in a hyperbolic form. Increases in adsorption coefficient or decreases in the desorption coefficient also result in considerable improvements in this rate. The model can be applied to other systems consisting of suspended solid substrate particles in liquid medium with microbial oxidation occurring on the particle surfaces (e.g., bacterial ore leaching). The results obtained from this model are in good agreement with published experimental data on microbial desulfurization of coal and bacterial ore leachin

ISSN:0006-3592    

DOI:10.1002/bit.260260608

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

年代:1984

数据来源: WILEY

摘要:

AbstractBatch growth tests were performed under both replicating and nonproliferating (no nitrogen source in medium) conditions with acclimated heterogenous populations that utilized phenol as a sole source of carbon and energy. It was shown that the acclimated populations could efficiently remove the toxic waste component phenol under nonproliferating conditions by utilizing an oxidative assimilation mechanism. The phenol was assimilated and converted into nonnitrogenous storage products. During the assimilation process, the cells had a tendency to excrete some product (nonsubstrate) chemical oxygen demand (COD). Bench‐scale oxidative assimilation units were operated by sequentially feeding a carbon source (phenol) and nitrogen source (ammonium sulfate) to heterogeneous populations. This demonstrated that, subsequent to the addition of the nitrogen source to the medium, the cells utilized the stored carbon for replication. Four of these units were operated at different phenol COD‐to‐ammonia‐nitrogen ratios of 10:1, 20:1, 40:1, and 50:1. All of these units demonstrated excellent removal of phenol using an oxidative assimilation mechanism. These results suggested the feasibility of utilizing a continuous flow oxidative assimilation process for the treatment of nitrogen‐deficient phenolic wastes. This process would be advantageous over conventional treatment processes in that it would realize a savings in chemical costs (ammonia as nitrogen source) and prevent leakage of excess ammonia from t

ISSN:0006-3592    

DOI:10.1002/bit.260260609

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.260260610

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.260260611

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

年代:1984

数据来源: WILEY