Production of moderately halotolerant, SDS stable alkaline protease from Bacillus cereus MTCC 6840 isolated from lake Nainital, Uttaranchal state, India

A moderately cold active, extracellular alkaline protease producing bacterium was isolated from a fresh water lake. The isolate was found to be a gram-positive, rod shaped organism later identified as Bacillus cereus MTCC 6840. The bacterium produced the maximum amount of enzyme when allowed to grow for 24 h at temperature 25 degrees and pH 9.0. Among a variety of substrates used, fructose as a carbon source and a combination of yeast extract and peptone as nitrogen source, supported the maximum protease production by the organism ( 120 U/ml). Fe++ and Co++ stimulated the enzyme activity whereas Ca++, Cu++, K+, Mg++ and Mn++ inhibited it to different extents. The protease was found to be highly stable in the presence of NaCl, SDS and acetone. Treatment with EDTA and PMSF resulted in the considerable loss of enzyme activity. The enzyme was found to be optimally active at pH 9.0 and temperature 20 degrees C.