Production, localization and glucose repression of β-glucosidase in Trichoderma longibrachiatum

✍ Scribed by Dr. D. K. Sandhu; M. S. Sidhu

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 512 KB
• Volume: 25
• Category: Article
• ISSN: 0233-111X
• DOI: 10.1002/jobm.3620250908

✦ Synopsis

Optimal product,ion of B-glucosidase was obtained by incubating the culture a t 27 "C in a growth medium that had an initial p H of 5.0 and contained cellobiose. The bulk of the enzyme (70%) was present in a cell-associated state (cell debris and cytosol) while only a small portion (30%) appeared in the culture filtrate. When cellulosic substrates were used, the major portion of the enzyme (70%) appeared in the extracellular fraction. A repression of the enzyme occurred in the presence of glucose. A drop of the p H of the medium during the exponential growth phase coincided with a rapid inactivation of t,he enzyme. The glucose effect was most likely mediated by adverse effects of low p H on the integrity of the enzyme.

#?-GIucosidase constitutes an integral part of the cellulase system involved in the hydrolysis of cellulose. The latter occurs in abundance in nature as waste. It can successfully be exploited to yield energy-rich compounds like glucose and ethanol. Fungi have been shown to be a good source of cellulase. Trichoderma species in particular, have attracted great attention since they possess exo-~-1,4-gIucanase (EC 3.2.1.91), endo-~-1,4-glucanase (EC 3.2.1.4) and P-glucosidase (EC 3.2.1.21) for stepwise degradation of cellulose. Although extensive studies have been carried out on the cellulase enzyme complex of Trichoderma species the #?-glucosidase has been studied in detail only in a few spieces (BISARIA and GHOSE 1981, KUBICEK 1983, WOODWARD and WISE-MAN 1982). The present paper reports on the production, localization and catabolite repression of #?-glucosidase in T. longibrachiatum.