Purification and characterization of a solvent, detergent and oxidizing agent tolerant protease from Bacillus cereus isolated from the Gulf of Khambhat

Twenty-eight organic solvent tolerant bacteria were isolated from crude oil contaminated samples, out of which, AK1871 isolate produced a solvent, detergent and oxidizing agent tolerant serine alkaline protease. Based on the morphological and biochemical characteristics, FAME analysis as well as 16S rRNA gene sequence, the isolate is identified as Bacillus cereus. A 58-fold purification of protease was achieved by a three-step purification procedure. This protease is active over a broad range of pH (6.0–9.0, optimum at 8.0); and temperature from 40 °C to 70 °C (optimum at 60 °C). Li+, Ba2+, K+, Mg2+ and Mn2+ did not affect, while heavy metals like Cr3+, Hg2+ and Cu2+ inactivated the enzyme. It is stable in the presence of non-ionic detergents (Triton X-100 and Tween 80), and oxidizing and bleaching agents (hydrogen peroxide). The protease exhibited noteworthy stability and activation in the presence of organic solvents with log P values equal to or more than 2.0. This protease could be used in detergent formulations, enzymatic peptide synthesis, biotransformation reactions and in the formulation of antifouling agent. This is the first report on the study of organic solvent tolerant protease from a marine organic solvent tolerant bacterium isolated from the Gulf of Khambhat.