A novel organic solvent tolerant protease from a newly isolated Geomicrobium sp. EMB2 (MTCC 10310): production optimization by response surface methodology.

Thirty-eight haloalkaliphilic bacterial strains were isolated from Sambhar Salt Lake, India and screened for their ability to secrete haloalkaliphilic proteases. Among them, a moderately halophilic, mesophilic and alkaliphilic potent strain Geomicrobium sp. EMB2 produced an extracellular protease, which was remarkably stable in organic solvents, salt, surfactants, detergents and alkaline pH. Statistically based experimental designs were applied to study the interactions and optimization of medium constituents for efficient protease production by Geomicrobium sp. EMB2. An overall 20-fold increase in protease production was achieved in the optimized medium (721 U/ml) as compared with the unoptimized medium (37 U/ml). The high production level coupled with novel properties makes it a prospective industrial enzyme. The Geomicrobium sp. EMB2 isolate is deposited in Microbial Type Culture Collection, Chandigarh, India with accession number MTCC 10310.