Abstract

Halophilic enzymes are potentially useful in many industries, particularly in food fermentation, pharmaceutical, textile, and leather for the treatment of saline and hypersaline wastewaters. In this study, a halophilic bacterium was isolated from saltpan environment, and was identified as Bacillus sp. Mk22 through biochemical test and 16S rRNA gene sequencing. During protease screening, the isolates produced 24 mm clear zone around the bacterial colony. The maximum production of proteases was due to the following conditions: 45°C, pH 8, 12% NaCl, carbon source glucose, nitrogen source skim milk powder and 42-h culture time, respectively. The protein was purified 16.5 fold, having 24.01% recovery, in DEAE-cellulose chromatography and 64 kDa molecular weight. Ca and Zn enhanced protease activity, while Hg strongly inhibited it. The protease was used to destain blood, ink, coffee and was active and stable under more than one extreme condition of high salt, pH, and temperature.

Key words: Saline environment, halophilic bacteria, protease, detergent.