摘要:

AbstractTaking the hydrolysis of sucrose by invertase immobilized on anion‐exchange resin as an example, the effects of mass‐transfer resistance on the apparent stability of immobilized enzyme (IME) and the optimal policy for an IME reaction in a fixed‐bed reactor have been studied theoretically and experimentally. The following results were obtained: (1) The effect of mass‐transfer resistance on the effective deactivation rate of IME is summarized in two parameters concerning the intraparticle diffusion αpand the interparticle αf. (2) At a constant processed amount of raw materials, there exists an optimal flow rate of reaction fluid to enhance the reactor performance while the mass‐transfer resistance shifts the optimal point. (3) The intrinsic deactivation rate of IME has been estimated from the relationship between the fractional conversion at the reactor outlet and the ope

ISSN:0006-3592    

DOI:10.1002/bit.260250112

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

年代:1983

数据来源: WILEY

摘要:

AbstractIn this work an evaluation was made of a wide variety of single and multiple pretreatment methods for enhancing the rate of enzymatic hydrolysis of wheat straw. A multiple pretreatment consisted of a physical pretreatment followed by a chemical pretreatment. The structural features of wheat straw, including the specific surface area, crystallinity index, and lignin content, were measured to understand the mechanism of the enhancement in the hydrolysis rate upon pretrement. It has been found that, in general, multiple pretreatments were not promising, since the hydrolysis rates rarely exceeded those achieved by single pretreatments. Ballmilling pretreatment was found to be effective in increasing the specific surface area and decreasing the crystallinity index. Treatment with ethylene glycol was highly effective in increasing the specific surface area, in addition to a high degree of delignification. Peracetic acid pretreatment was highly effective in delignifying substrate. Among multiple pretreatments, those involving peracetic acid treatment generally had lower crystallinity indices and lignin content values. The relationship between the hydrolysis rate and the set of structural features indicated that an increase in surface area and a decrease in the crystallinity and lignin content enhance the hydrolysis; the specific surface area is the most influential of the structural features, followed by the lignin content.

ISSN:0006-3592    

DOI:10.1002/bit.260250113

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

年代:1983

数据来源: WILEY

摘要:

AbstractFermentation of xylose byKlebsiella pneumoniae(ATCC 8724, formerly known asAerobacter aerogenes) carried out in our laboratory yields 2,3‐butanediol as the major product. Experimental data obtained in this work cannot be explained by the model presently in the literature for the formation of 2,3‐butanediol isomers from acetoin isomers. A new model is proposed with the existence of two acetoin reductases and an acetoin racemase. The two reductases were separated and their stereospecificity determined. Extension of the model of other microorganisms is discus

ISSN:0006-3592    

DOI:10.1002/bit.260250114

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe effects of temperature (35 and 55°C) and straw–manure mixtures (90, 75, 50, and 0% straw) on methane (CH4) production were studied using laboratory‐scale fermentors. Batch fermentations showed that the ultimate CH4yield (B0) of straw–manure mixtures was directly proportional to the relative proportion andB0of the individual components. Also, hammer or ball milling did not increase theB0of straw. Kinetic analysis showed that fermentation stress occurred when the straw content of straw–manure mixtures was higher than 40% at 35°C, or higher than 75% at 55°C. This fermentation stress was observed to occur when the free ammonia concentration was bel

ISSN:0006-3592    

DOI:10.1002/bit.260250115

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

年代:1983

数据来源: WILEY

摘要:

AbstractSelected samples of waste microbial biomass used in industrial fermentation processes and wastewater biological treatment plants have been studied for their radium biosorption ability from aqueous solutions. Equilibrium biosorption isotherms have been used to quantify the radium uptake capacity of the various types of biomass which were also compared to two types of activated carbon. Solution pH affected the observed uptake significantly. In general, the biomass types that showed appreciable sorption capacity exhibited maximum uptake between pH 7 and 10. The uptake was reduced considerably at pH 4 and little or no uptake was observed at pH 2. Radium biosorptive uptake capacities of the order of 4.5 × 104nCi/g, at pH 7 and at an equilibrium radium concentration of 1000 pCi/L, were determined for a mixed culture, while the biomass ofPenicillium chrysogenumadsorbed 5 × 104nCi/g radium under the same conditions. The highest uptake value for a sample of F‐400 granular activated carbon was 3600 nCi/g at pH 7 and 1000 pCi/L radium concentration. The biosorptive radium uptake of microbial biomass is compared to literature values for other types of adsorbents. The most effective biomass types studied exhibited radium removals in excess of 99% of the radium in solut

ISSN:0006-3592    

DOI:10.1002/bit.260250116

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

年代:1983

数据来源: WILEY

摘要:

AbstractA stable immobilized preparation of fumarase (EC 4.2.1.2) was obtained by entrapment of rat liver mitochondria in acrylamide polymerized by using gamma irradiation (100 kR). The enhanced stability and the efficiency of the entrapped enzyme have shown potential for repeated use for the production ofL‐malic acid from fumaric acid. The possible formation of succinic acid in the system could be controlled by incorporating malonate along with detergents such as sodium deoxycholate or sodium dodecylsulfate in the reactor syste

ISSN:0006-3592    

DOI:10.1002/bit.260250117

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

年代:1983

数据来源: WILEY

摘要:

AbstractA computer‐aided methodology is developed for on‐line monitoring and control of cell growth in fed‐batch penicillin fermentation using a semidefined medium containing low corn steep liquor concentration (5.7 g/L). Cell growth is monitored and controlled with the use of experimental correlation and carbon‐balancing equatiions on a real‐time basis throughout the fermentation. Through a combination of feed‐forward and feedback control of sugar addition, residual glucose concentration in the broth was maintained below 1 g/L and cell‐growth rate was kept at constant at preset vaiues. The accuracy and reproducibility of this technique are demonstrated. The use of real‐time control of cell growth is expected to aid future investigations of this antibiot

ISSN:0006-3592    

DOI:10.1002/bit.260250118

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

年代:1983

数据来源: WILEY

摘要:

AbstractTo broaden the practicality of on‐line growth monitoring and control, its application in fedbatch penicillin fermentation using high corn steep liquor (CSL) concentration (53 g/L) is demonstrated. By employing a calculation method that considers the vagaries of CSL consumption, overall and instantaneous carbon‐balancing equations are successfully used to calculate, on‐line, the cell concentration and instantaneous specific growth rate in the penicillin production phase. As a consequence, these equations, together with a feedback control strategy, enable the computer control of glucose feed and maintenance of the preselected production‐phase growth rate with error less than 0.

ISSN:0006-3592    

DOI:10.1002/bit.260250119

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe sorption characteristics of the cellulase system ofTalaromyces emersoniion various cellulosic substrates were examined. Analysis of reaction mixture supernatants by electrophoresis and enzyme assay showed that all components of the cellulase system were rapidly adsorbed by cellulose and then gradually returned to the liquid phase as the hydrolysis of the substrate progressed. The extent of adsorption in the rapid phase was influenced by pH, temperature, the nature of the substrate, and its concentration.

ISSN:0006-3592    

DOI:10.1002/bit.260250120

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe potential of continuous isopropanol–butanol–ethanol (IBE) fermentation by Ca–alginate‐immobilizedClostridium beijerinckiicells in a continuous stirred‐tank reactor is investigated. A mathematical model is presented to describe steady‐state reactor performance. It appeared to be possible to use the biocatalyst particles repeatedly for successive fermentations (at least three times for a total duration of two months). Reactor productivity was 6–16 times higher than that of a batch fermentation (free cells), while the solvents yield was also increased. Measurements of substrate, product, and biomass concentrations were only partially in agreement with the model; however, a solid basis for further technological developement of the process

ISSN:0006-3592    

DOI:10.1002/bit.260250121

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

年代:1983

数据来源: WILEY