Biosynthesis of cellulolytic enzymes by Tricothecium roseum with citric acid mediated induction

Abstract

Tricothecium roseum, an unexplored fungus for the production of cellulolytic enzymes, was used in this study for carboxymethylcellulase (CMcase) and b-glucosidase production. The culture filtrate of this organism exhibited highest total cellulolytic activity and extracellular protein content on 9th day during the course of its growth on potato dextrose yeast extract (PDYE) broth medium supplemented with 1.0% (w/v) carboxymethylcellulose. Among various soluble carbon and complex nitrogen sources tested in this study, carboxymethylcellulose and peptone supported maximum production of both cellulolytic enzymes. Under all suitable growth conditions, the enzyme biosynthesis was remarkably increased when the inducer citric acid was added to the PDYE media containing carboxymethylcellulose. Maximum CMcase production (1.59 U/ml) and b-glucosidase production (1.82 U/ml) were achieved in citric acid amended PDYE media at 37°C. Both the cellulolytic enzyme production was highest at initial pH 6.5 and after 7 days incubation. The study clearly demonstrated that citric acid is a good inducer for extracellular cellulolytic enzyme production by the fungus.