摘要:

AbstractContinuous culture studies have been carried out growingTrichoderma virideQM 9123 in a 10 liter stirred fermentor on a medium containing commercial glucose as the carbon source. Experiments were carried out at 30°C and at three controlled pH values of 2.5, 3.0, and 4.0, over a range of dilution rates from 0.01 to 0.11 hr−1. Steady‐state values of cell, glucose, and cellulase concentration oxygen tension, and outlet gas oxygen partial pressure were recorded. Values of maximum specific growth rate, endogenous metabolism coefficient, Michaelis‐Menten coefficient, yield and maintenance coefficient for glucose were derived and correlated the effect of the hydrogen ion concentration. Specific oxygen uptake rates were correlated with specific growth rates and absorption coefficients were shown to be a function of dilution rate independent of pH. Some data on cellulase biosynthesis were examined and correlated in terms of a maturation time

ISSN:0006-3592    

DOI:10.1002/bit.260190702

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

年代:1977

数据来源: WILEY

摘要:

AbstractThree distinct cellobiase components were isolated from a commercialTrichoderma viridecellulase preparation by repeated chromatography on DEAE cellulose eluting by a salt gradient. The purified cellobiase preparations were evaluated for physical properties, kinetics, and mechanism. Results from this work include: (1) development of a one step enzyme purification procedure using DEAE‐cellulose; (2) isolation of three chromatographically distinct, yet kinetically similar, cellobiase fractions of molecular weight of ∼76,000; (3) determination of kinetics which shows that cellobiase hydrolyzes cellobiose by a noncompetitive mechanism and that the product, glucose, inhibits the enzyme, and (4) development of an equation, based on the mechanism of cellobiase action, which accurately predicts the time course of cellobiose hydrolysis over an eightfold range of substrate concentration and conversions of up to 90%. Based on the data presented in the paper, it is shown that product inhibition of cellobiase significantly retards the rate of cellobiose hydroly

ISSN:0006-3592    

DOI:10.1002/bit.260190703

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe response of a polarographic oxygen electrode to a step change and to an exponential change in bulk oxygen concentration was studied theoretically and experimentally for the case where there is a significant liquid film resistance at the outerside of the membrane‐covered electrode. The probe response has been described considering the start‐up period of the concentration changes (the period of time that will elapse before the new concentration level is established and/or before the volumetric mass transfer coefficientkLaregains its steady‐state value after the gas supply is opened to the fermentor). A linear change of the pertinent characteristics is assumed during this start‐up period. It is shown that a substantial error could be introduced by neglecting the start‐up period for cases frequently occurring in practice. In addition, the dependences of the probe response on the direct contact of bubbles with an electrode and on the fluid flow field around it were

ISSN:0006-3592    

DOI:10.1002/bit.260190704

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

年代:1977

数据来源: WILEY

摘要:

AbstractCorynebacterium hydrocarboclastusKY 8835 grew in the acetate medium and accumulated 28mMCorynecins which was the highest production yield among the processes using various carbon sources. Selective production of Corynecin I (over 90% of all Corynecins), which had been desired for increase of the product yield, was achieved in this acetate medium. To keep the concentration of acetate, ammonium, and phosphate ions in the optimum range throughout the fermentation, a solution containing CH3COOH (50%), CH3COONH4(9%), and KH2PO4(0.2%) was fed continuously to the culture medium as the pH controlling agent. The addition of KCl (1%) and NaCl (1%) to the medium at 12 hr after inoculation stimulated the production of Corynecins.

ISSN:0006-3592    

DOI:10.1002/bit.260190705

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

年代:1977

数据来源: WILEY

摘要:

AbstractEthanol production byKluyveromyces fragilisandSaccharomyces cerevisiaewas studied using cottage cheese whey in which 80 to 90% of the lactose present had been prehydrolyzed to glucose and galactose. Complete fermentation of the sugar byK. fragilisrequired 120 hr at 30°C in lactase‐hydrolyzed whey compared to 72 hr in nonhydrolyzed whey. This effect was due to a diauxic fermentation pattern in lactase‐hydrolyzed whey with glucose being fermented before galactose. Ethanol yields of about 2% were obtained in both types of whey whenK. fragiliswas the organism used for fermentation.Saccharomyces cerevisiaeproduced alcohol from glucose more rapidly thanK. fragilis, but galactose was fermented only whenS. cerevisiaewas pregrown on galactose. Slightly lower alcohol yields were obtained withS. cerevisiae, owing to the presence of some lactose in the whey which was not fermented by this organism. Although prehydrolysis of lactose in whey and whey fractions is advantageous in that microbial species unable to ferment lactose may be utilized, diauxie and galactose utilization problems must be consid

ISSN:0006-3592    

DOI:10.1002/bit.260190706

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe overall rate of reaction of a gel‐immobilized urease particle necessarily depends upon the hydrogen ion concentrations within the particle. When the particle is unbuffered, the internal hydrogen ion concentrations are a consequence of the local rates of reaction and the rate of egress of the products of hydrolysis. A simple apparatus has been devised which allows a fairly rapid determination of the hydrogen ion concentration in the center of a particle for any given size, enzyme concentration, substrate concentration, and external pH. The products of urea hydrolysis are self‐buffering in the region of pH 8.83 and for an external pH less than the self‐buffering pH, the pH within the particle is increased because of the reaction. When the external pH is greater than the self‐buffering pH, the converse occurs. The pH at the center of the particle approaches the self‐buffering pH with an increase in particle size and enzyme concentration. The external pH necessarily differs in effect when above or below the self‐buffering pH. An increase in the external substrate concentration has a limited effect, simply rendering the local rates of reaction to be of zero order. The center‐line pH and therefore all internal hydrogen ion concentrations depend upon the parameter\documentclass{article}\pagestyle{empty}\begin{document}$ L\sqrt {\rho _e} $\end{document}and the external pH. Differences between the external and center‐line pH values of the order of units are unexceptional. The implications of the internal pH profiles on the local and overall rates of reacti

ISSN:0006-3592    

DOI:10.1002/bit.260190707

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

年代:1977

数据来源: WILEY

摘要:

AbstractThe overall rates of reaction of unbuffered gel‐immobilized urease particles have been investigated with the aid of a packed‐bed differential recycle reactor. Both substrate and enzyme concentrations have received attention. Cylindrical gel particles contained within impermeable tubelets were used to provide the physical strength necessary for the packed‐bed arrangement and a one dimensional diffusion path to aid understanding of the complex interactions between substrate and product diffusion, and their effect on the reactions taking place. The experimental data have been interpreted with the aid of an enzyme rate equation (ERE) which relates the free solution characteristics of the enzyme to the conditions within a diffusion limited particle. The internal hydrogen ion profiles have been accommodated by a lumped parameter, the apparent pH (pHapp). Two methods have been suggested for the calculation of pHappand the loss of activity on particle preparation, these methods are based on the use of the ERE in conjunction with experimental

ISSN:0006-3592    

DOI:10.1002/bit.260190708

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

年代:1977

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260190709

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

年代:1977

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260190710

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

年代:1977

数据来源: WILEY

ISSN:0006-3592    

DOI:10.1002/bit.260190711

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

年代:1977

数据来源: WILEY