Optimization of mycolytic enzymes (Chitinase, β1,3-Glucanase and Cellulase) production by Bacillus subtilis, a potential biocontrol agent using one-factor approach

摘要

This study presents one-factor approach for optimization of growth and physical parameters for increasing production of three mycolytic enzymes viz. chitinase, β-l,3-glucanase and β1,4-glucanase (cellulase) by B.subtilis, a potent biocontrol agent. Maximum enzyme activity of all three enzymes was observed in the following physical parameters: pH 7.0, temperature of 30℃, and incubation period of 72h. Optimum nutritional parameters were found to be as follows: Carboxymethyl cellulose (CMC, 10g/L); Corn steep liquor (CSL, lg/L) or KNO_3(lg/L), CaCL, (5mM)and Triton X 100 (0.1% v/v). Using one factor approach, production of all three enzymes significantly increased for chitinase (5.49 folds); a-1,3-glucanase (7.39 folds) and cellulase (1.91 folds) respectively as compared to the un-optimized media containing Nutrient broth. The crude mycolytic enzymes had activity in acidic pH (4 - 6) and temperature (50 - 60℃) range with optima at pH 6.0 and 55℃, respectively. However, chitinase showed two pH optima at pH 6 and 11 indicating the possibility of having two isoforms. The enzymes showed varied response to metal ions. Identification of essential nutrients affecting co-production of three enzymes by a single strain would help to formulate a suitable medium for their concerted production. Moreover, low cost cellulosic materials can be used as carbon source for these enzymes production by the isolate for industrial and agricultural applications.