摘要:

AbstractIt was confirmed that simultaneous saccharification and fermentation are effective for accelerating enzymatic saccharification of cellulose. In this work, the effects of ethanol on the saccharification of tissue paper byTrichodermacellulase (Meicelase CEPB) have been investigated. The following results were obtained. (1) Saccharification was inhibited by at least 0.2Methanol. (2) Less than 4Methanol did not affect the enzymatic activities of β‐glucosidase and endoglucanase (Cx) at all. The thermal stability of endoglucanase was not also varied by ethanol. (3) It is suggested that ethanol depresses the adsorption of exoglucanase on cellulose. (4) The rate expression of saccharification of cellulose in the presense of ethanol is proposed. (5) The inhibititory effect of ethanol was found to become more significant in the later stages of the reaction than just the initial sta

ISSN:0006-3592    

DOI:10.1002/bit.260270402

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

年代:1985

数据来源: WILEY

摘要:

AbstractScale‐down experiments in antibiotic biosynthesis were performed by transferring the corresponding amounts of fermentation broth from industrial to laboratory and pilot‐plant fermentors where the cultivation process was continued at different cultivation conditions. A previously proposed mathematical model was used to explain the experimental results. The effects of temperature, agitation‐aeration intensity, and medium addition during the process were investigated. Computer simulation data were fitted to the experimental data, and good agreement was found. As a consequence of increasing temperature up to 37°C, increases in the specific growth and autolysis rates as well as the specific rates of antibiotic synthesis and carbohydrate utilization were in evidence. Temperature increases of up to 40°C caused a lower oxytetracycline yield. The effect of increased oxygen transfer rate on oxytetracycline biosynthesis was more pronounced at higher temperatures than at lower cultivation temperatures. Culture differentiation (strain segregation) was also studied; it was found that the increased cultivation temperature could be favorable for the growth of biomass active in oxytetracycline biosynthesis. Results of experiments at the pilot‐plant scale showed that fed batch and repeated fed batch cultures could be successfully applied and the period of intensive antibiotic synthesis could be prolonged sign

ISSN:0006-3592    

DOI:10.1002/bit.260270403

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe integrated rate equation of Huang, originally used to describe the hydrolysis of insoluble acid treated cellulose, is shown equally applicable in describing the hydrolysis of carboxymethylcellulose (CMC) using a dilution series ofCellulomonas sp. ATCC 21399crude cellulase as enzyme preparation. Interpretation of the progress curves of hydrolysis of CMC according to the integrated rate equation is used to calculate a standard formula for the conversion of the rate of hydrolysis into the initial velocity of hydrolysis. The validity of the standard formula is tested, using enzyme preparations fromCellulomonasgrown under varied conditions, and enzyme preparations containing purified endoglucanases fromCellulomonas.

ISSN:0006-3592    

DOI:10.1002/bit.260270404

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

年代:1985

数据来源: WILEY

摘要:

AbstractPorcine pepsin was immobilized by chemical aggregation using glutaraldehyde as a bifunctional crosslinking agent. The immobilzed pepsin followed Michaelis–Menten kinetics (Km= 5.3 × 10−5M) and the yield of immobilization was 91%. The activation energy of the immobilized preparation was 90,613 cal/mol as compared to 67,532 cal/mol for native pepsin. Using acid‐denatured hemoglobin andN‐acetyl phenyl‐alanyl‐3, 5‐diiodotyrosine (APDT) as substrates, the activities shown by the immobilized pepsin were, respectively, 67 and 79% that of the soluble pepsin. The immobiized pepsin showed marked stabilization against pH, temperature, urea, and guanidine hydrochloride. The activity of the immobilized preparation in the presence of urea was greater when hemoglobin was used as the substrate than when APDT was used as substrate. Storage of the preparation under refrigerated conditions for 160 days showed 58% retention in enzyme activity. The immobilized pepsin can be removed from the reaction mixture volume easily, retaining nearly 100% of its activity even after being used in seven cons

ISSN:0006-3592    

DOI:10.1002/bit.260270405

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

年代:1985

数据来源: WILEY

摘要:

AbstractOptically activeD‐arylglycines, which are of interest for preparation of semisynthetic penicillins and cephalosporins, were isolated from the racemic mixtures of their derivatives using immobilized proteolytic enzyme subtilisin (EC No. 3.4.4. 16). The performance of these reactions in two‐phase systems, consisting of water and an immiscible organic solvent, improved the yield, purity, and economics of the process by increasing the substrate solubility and reducing the rate of nonenzymatic hydrolysis. The proportion of the organic phase can be as much as 75% of the overall volume without seriously impairing the enzymatic activity. The optically pureD‐andL‐arylglycines were liberated from theirD‐ andL‐derivatives by acid hydrolysis. The substituent influence of the various arylglycine derivatives on the rate of the enzymatic cleavage reaction was i

ISSN:0006-3592    

DOI:10.1002/bit.260270406

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

年代:1985

数据来源: WILEY

摘要:

AbstractAn analysis of the radial flow cell is presented to show that the assumption of creeping laminar flow should be used cautiously. Simple models which account for the influence of fluid inertial forces over most of the width of the plate are reviewed. A modified Reynolds number is introduced which may be used to test the validity of the creeping flow solution.

ISSN:0006-3592    

DOI:10.1002/bit.260270407

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe effects of four pH steps and one dilution rate step are described for an ammonia–nitrogen‐limited continuous culture ofEscherichia coliB/r. Two of the pH steps, 6.06–5.49 and 5.96–5.60, led to prolonged transients in both cell density and rate‐limiting nutrient concentration. The other two pH steps, 6.20–5.96 and 5.60–6.20, had almost no effect on the culture. The dilution rate step led to a sharp transition in the steady‐state external pyruvate concentration. Monitoring of the external pyruvate concentration for the pH 5.96–5.60 step revealed that the transient phase continued long after the cell density and rate‐limiting nutrient concentration returned to steady‐state values. The implications for industrial and laboratory fermen

ISSN:0006-3592    

DOI:10.1002/bit.260270408

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

年代:1985

数据来源: WILEY

摘要:

AbstractAldehyde oxidase (E.C. 1.2.3.1) was isolated from rabbit liver and two potential bioaffinity ligands, i.e., 3‐aminocarbonyl‐1‐benzyl‐6‐methylpyridinium bromide and 3‐aminocarbonyl‐1‐benzyl‐4,6‐dimethylpyridinium chloride, were tested for their applicability in a purification procedure for this enzyme. Various supports and different coupling methods were investigated for the immobilization of aldehyde oxidase. Adsorption ton‐hexyl‐ andn‐octylamine‐substituted Sepharose 4B and DEAE Sepharose 6B gave the best retention of aldehyde oxidase activity. The storage stability of free enzyme and enzyme immobilized ton‐octylamine‐substituted Sepharose 4B was studied in several buffers at pH 7.8 and 9.0. This showed that the stability of immobilized enzyme was much less than that of free enzyme. The apparent operational stability of the immobilized enzyme preparation, however, improved substantially compared to soluble enzyme, although the corresponding product yield is still very poor. Coimmobilization of catalase and/or superoxide dismutase provided no significant increase of the apparent operational stability and product yield. A positive effect on both parameters was found for aldehyde oxidase‐n‐alkylamine Sepharose 4B preparations by increasing the amount of enzyme adsorbed per unit weight of support, whereas the productivity of these p

ISSN:0006-3592    

DOI:10.1002/bit.260270409

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

年代:1985

数据来源: WILEY

摘要:

AbstractA novel process for the production of extracellular carboxymethylcellulase (CMCase) and xylanase by fermentation under nonaseptic or nonsterile conditions is described. The fermentation process is carried out under very acidic conditions of pH 2.0 by using a acidophilic cellulolytic fungus. Microbial contamination is avoided or minimized to an insignificant level under this acid pH condition. The culture medium for this production consists of a carbon source from cellulosics or lignocellulosics, such as Na–CMC, xylan, Avicel cellulose, cellulose powder, α‐cellulose, sawdust, etc., or a mixture of the forementioned together with simple ingredients such as (NH4)2SO4, K2HPO4, MgSO4and NaNO3. The fermentation is carried out at room temperature (28–30°C), under aerobic conditions, and without controlling the pH. The CMCase and xylanase produced are stable under very simple storage conditions, such as in the fresh culture medium not containing the substrate for a period of 3 days, at any temperature from 0 to 30°C. These extracellular enzymes have an optimum pH around 3, with the best range of pH from 2.0 to 3.6, for any temperature between 15 and 60°C. The optimum temperatures are 55°C for CMCase activity and 25–50°C for xylanase activity, at any pH between 2.0 and 5.2. The apparent Michaelis constantsKmare 2.6 and 1.5 mg/mL for CMCase and xylanase of the culture filtrate,

ISSN:0006-3592    

DOI:10.1002/bit.260270410

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe enzymatic hydrolysis of cellulose to glucose involves the formation of cellobiose as an intermediate. It has been found necessary1to add cellobiase fromAspergillus niger(NOVO) to the cellobiase component ofTrichoderma reeseimutant Rut C‐30 (Natick) cellulase enzymes in order to obtain after 48 h complete conversion of the cellobiose formed in the enzymatic hydrolysis of biomass. This study of the cellobiase activity of these two enzyme sources was undertaken as a first step in the formation of a kinetic model for cellulose hydrolysis that can be used in process design. In order to cover the full range of cellobiose concentrations, it was necessary to develop separate kinetic parameters for high‐ and low‐concentration ranges of cellobiose for the enzymes from each organism. Competitive glucose inhibition was observed with the enzymes from both organisms. Substrate inhibition was observed only with theA. nigeren

ISSN:0006-3592    

DOI:10.1002/bit.260270411

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

年代:1985

数据来源: WILEY