Optimization and Characterization of Thermostable Endo and Exocellulases by Humicola sp. SKESMBKU03

Abstract

Humicola sp. SKESMBKU03, a cellulase producer was isolated from horse dung manure collected from Hyderabad, Telangana. In the present study, endo and exoglucanase production from Humicola sp. SKESMBKU03 was studied and optimization of the cultural conditions to enhance production of enzymes has been reported. Among the twenty fungal cellulase producers isolated from different thermogenic habitats, the fungal strain ‘HD3’ identified as Humicola sp. SKESMBKU03 exhibited highest cellulase activity by plate screening assay. To enhance the production level of the enzyme, different cultural conditions were optimized and observed that optimum pH and temperature for endo and exoglucanase production was 5.0 and 45^oC respectively. Maximum growth as well as enzyme production was recorded on 3rd day of incubation period in shake flask (100RPM) containing Mandel’s Weber medium. Urea and malt extract among the organic nitrogen sources while ammonium chloride as inorganic nitrogen source were found to be the best nitrogen source (0.2%) for endo and exoglucanase production. The endo and exoglucanase activities are higher in media containing glucose as their carbon source (1%) followed by xylose and lactose. The organism showed maximum dry weight in pH of 9.0-10.0, temperature of 45^oC, cellulose as carbon sources, yeast extract and malt extract of nitrogen source. The endo and exocellulases produced by the Humicola sp. SKESMBKU03 are highly stable at pH 8.0 and temperature of 75⁰C. The results indicate that the endo and exocellulases produced by Humicola sp. SKESMBKU03 are more stable at high temperature and alkaline pH.