Two β-glucosidase activities in Fibrobacter succinogenes S85

C. J. Buchanan, W. J. Mitchell

Research output: Contribution to journalArticle

Abstract

Few bacteria are capable of degrading crystalline cellulose but there is considerable interest in the properties of enzyme systems with this capability. In the bovine and ovine rumen the principal cellulolytic bacterium is Fibrobacter (formerly Bacteroides) succinogenes. The cellulase system of this organism is composed of multiple enzyme components, including a constitutive and cell-associated ß-glucosidase active against cellobiose. The properties of the ß-glucosidase activity have been investigated with the chromogenic substrate p-nitrophenyl ß-D-glucoside (pNPG). Hydrolytic activity against pNPG was located primarily in the cytoplasm and the cytoplasmic membrane but showed a gradual migration to the periplasm during growth on either glucose or cellobiose. Activity against cellobiose was found in the periplasm in significant amounts in all growth phases. Of the ß-glucosides tested, only cellobiose and pNPG were hydrolysed by crude cell extracts. In the presence of cellobiose, however, the rate of hydrolysis of pNPG was stimulated up to 10-fold, and extracts hydrolysed methylumbelliferyl ß-D-glucoside, 5-bromo-4-chloro-3-indolyl ß-D-glucoside, arbutin and aesculin. Activities against pNPG in the presence and absence of cellobiose displayed similar instability in the presence of oxygen; both were stabilized by dithiothreitol and the temperature and pH optima were identical. A significant proportion of the membrane-associated ß-glucosidase was released by treatment with 0.3 mol/l KCl, and fractionation by chromatography on CM-cellulose showed the presence of two activities against pNPG, only one of which was stimulated by cellobiose.

Original languageEnglish
Pages (from-to)243-250
Number of pages8
JournalJournal of Applied Bacteriology
Volume73
Issue number3
Publication statusPublished - 1992

Fingerprint Dive into the research topics of 'Two β-glucosidase activities in Fibrobacter succinogenes S85'. Together they form a unique fingerprint.

  • Cite this

    Buchanan, C. J., & Mitchell, W. J. (1992). Two β-glucosidase activities in Fibrobacter succinogenes S85. Journal of Applied Bacteriology, 73(3), 243-250.