Regulation of cellulase from Ruminococcus

Abstract

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...

Production of Enzymes Degrading Plant Cell Walls and Fermentation of Cellobiose by Ruminococcus flavefaciens in Batch and Continuous Culture

“…The greatly enhanced CMcellulase activity in cellobiose-limited continuous cultures suggested that synthesis of this enzyme is catabolite repressed, as previously reported for the cellulase of R. albus (Fusee & Leatherwood, 1972) and a cellulolytic strain of PseudumunasJluorescens (Suzuki, 1975).…”

Regulation of Cellulase Formation in Clostridium thermocellum

“…Previous studies with C. thermocellum (Garcia-Martinez et al, 1980;Hammerstrom et a/., 1955) and other cellulolytic bacteria (Fusee & Leatherwood, 1972;Lee & Blackburn, 1975) demonstrated that carboxymethylcellulase is not strongly repressed by catabolism of soluble carbon sources. This was surprising since it would be advantageous for C. thermocellum to repress its level of cellulase if a soluble carbon source is available in the medium.…”

Ecology of Microbial Cellulose Degradation

“…They appear to be similar. Results of early studies by Fusee and Leatherwood (1971) suggested that the Ruminococcus cellulase system is depressed by the presence of disaccharides such as cellobiose, sucrose, and lactose and also that cellobiose, if present, must first be used before cellulose is degraded. Inhibition of cellulose digestion by cellobiose, and to a lesser degree by glucose, was also observed by Smith et al (1973).…”