Optimal conditions for production of extracellular protease from newly isolated Bacillus cereus strain CA15

Abstract

An alkaline protease producer Bacillus sp. strain CA15 was isolated from soil. The microorganism was found to be closely related to Bacillus cereus based on 16S ribosomal DNA sequencing. The culture conditions for higher protease production were optimized with respect to carbon and nitrogen sources, metal ions, pH and temperature. Maximum protease production was obtained in the medium supplemented with 1% skim milk, 1% starch and 0.6% MgSO 4 .7H 2 O, initial pH 8.0 at 35°C. The best enzyme production was obtained during the stationary phase in which the cell density reached to 1.8x108 cells/mL. The level of protease was found to be low in the presence of inorganic nitrogen sources. The protease production was diminished in the presence of sucrose and lactose. The extreme stability towards Triton X-100, Tween 20 and SDS was observed by Bacillus sp. CA15 alkaline protease. The enzyme activity was inhibited by PMSF suggested that presence of serine residues at the active sites.