Salicola sp. strain SBJ9: a novel extremely halophilic bacterium with an interesting protease activity

A number of newly isolated halophilic microorganisms were screened for protease production. A bacterium designated as strain SBJ9 showed an important enzyme production at high salt concentrations and was then retained. The 16S DNA identification put this strain in the genus of Salicola with two reference species only. Protease production was higher at salinities ranging from 150 to 200 g/l (3.2 M) NaCl, when monitored at 35 °C and pH 7. The protease activity was optimal at 2.5 MNaCl, 40°C and pH 8, with high stability at wide ranges of salinity (1-5 MNaCl), temperatures (20- 70 °C) and pH values (5- 11). It was slightly improved by 5 mM CaCl₂ and totally inhibited by PMSF which indicated the dominance of serine proteases. Besides, it was perfectly stable in the presence of many detergent additives and organic solvents at high concentrations. These important features make Salicola sp. strain SBJ9 protease activity a good candidate for many industrial applications such as detergency and organic synthesis.