FUSEE, M. C., et J. M. LEATHERWOOD. 1972. Regulation of cellulase from Rln~ri~rococcrrs. Can. J.Microbiol. 18: 347-353. On a examine la regulation de la cellulose chez Rr~lninococcrrs nlbrrs et R. flavefacielu. L'hydrolyse de la cellulose, cornme mesuree par la for~nation des zones claires autour des colonies bacteriennes qui se developpent sur cellulose gelosee en tubes enrobes, est inhibee par des niveaux moyens de cellobiose. U n intermediaire dans le n~etabolisme de la cellobiose peut Ctrc responsable de I'inhibition parce que des lignees qui peuvent ~~tiliser le sucrose ou le glucose sont similairement inhibees par ces sources d'energie. L'inhibition de la cellulose a ete etudiee en relation soit de la repression de la synthkse de l'enzyme, soit de I'inhibition de I'activitC enzymatiq~~e par les produits. 1 1 n'y a aucune inhibition par la cellobiose ajoutte soit au milieu d'essai enzymatique de routine soit au milieu d'essai dont des faibles concentrations de carboxymethylcellulose sont utilisees. Un mecanis~ne de repression est indiqut par la diminution de I'activite specifique des cultures qui se sont developpees en presence de fortes concentrations de cellobiose. L'activite specifique a Cte calculee comme Ctant I'activitk enzy~natiq~~e sur le carboxymCthylcellulose en regard de la croissance des cellules. Le mecanis~ne de repression n'a pas ete differentie du model propose par Jacob et Monod et de la repression par les catabolites. Rr~~~zi~~ococcrr~ nlbrrs, cultive dans un milieu liquide de cellulose et de cellobiose, ~nontre un mode de croissance diauxique semblable a celui decrit par Monod. FUSEE, M. C., and J. M. LEATHERWOOD. 1972. Regulation of cellulase from Rrm~i~~ococcus. Can. J.Microbiol. 18: 347-353. The regulation of cellulase was examined in Rrrl?~i~lococcrrs albrls and R. flavefacietu. Hydrolysis of cellulose, as shown by the formation of clear zones around the colonies of bacteria grown in celluloseagar roll tubes, was inhibited by moderate levels of cellobiose. An intermediate in the metabolism of cellobiose may be responsible for the inhibition since strains which can use either sucrose or lactose were similarly inhibited by these energy sources. The inhibition of cellulase was examined in relation to either repression of enzyme synthesis or product inhibition of the enzyme activity. There was no inhibition by cellobiose added either to the routine enzymatic assay or to assays using low concentrations of carboxymethylcellulose. Arepression mechanism was indicated by the decrease in specific activity of cultures grown in higher concentrations of cellobiose. The specific activity was calculated as the enzymatic activity oncarboxyn~ethylcellulose with respect to cell growth. The mechanism of repression was not distinguished between the model proposed by Jacob and Monod and catabolite repression. The growth of R. albrrs cultured in cellobiose-cellulose liquid medium exhibited a diauxic pattern similar to that described by Monod.As early as 1932, Sarles et al. (24), working with thermophilic ce...

Whole cells of Escherichia coli containing aspartase activity were immobilized by mixing a cell suspension with a liquid isocyanate-capped polyurethane prepolymer (Hypol). The immobilized cell preparation was used to convert ammonium fumarate to L-aspartic acid. Properties of the immobilized E. coli cells containing aspartase were investigated with a batch reactor. A 1.67-fold increase in the L-aspartic acid production rate was observed at 37°C as compared to 25°C operating temperature. The pH optimum was broad, ranging from 8.5 to 9.2. Increasing the concentration of ammonium fumarate to 1.5 M from 1.0 M negatively affected the reaction rate. L-Aspartic acid was produced at an average rate of 2.18 x 10-4 mol/min per g (wet weight) of immobilized E. coli cells with a 37°C substrate solution consisting of 1.0 M ammonium fumarate with 1 mM

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Whole cells of Pseudomonas dacunhae containing L-aspartate 0-decarboxylase activity were immobilized by mixing a cell suspension with a liquid isocyanate-capped polyurethane prepolymer (Hypol; W. R. Grace & Co., Lexington, Mass.). The immobilized cell preparation was used to convert L-aspartic acid to L-alanine. Properties of the immobilized P. dacunhae cells containing aspartate 0-decarboxylase activity were investigated with batch reactors. Retention of enzyme activity was observed to be as much as 100% when cell lysis was allowed to occur before immobilization. The pH and temperature optima were determined to be 5.5 and 45°C, respectively. Immobilized P. dacunhae L-aspartate ,-decarboxylase activity was stabilized by the addition of 0.1 mM pyridoxal-5-phosphate and 0.1 mM a-ketoglutaric acid to a 1.7 M ammonium aspartate (pH 5.5) substrate solution. Under conditions of semicontinuous use in a batch reactor, a 2.5% loss in immobilized Laspartate ,(-decarboxylase activity was observed over a 31-day period.