Production and properties of thermostable proteases from bacillus thermoleovorans strain HSR

Abstract

The thermophilic bacterium Bacillus thermoleovorans strain HSR secretes thermostable extracellular proteases when cultivated in the presence of tryptone. The proteases which are found to be of the metallo-protease type, showed maximal activity when incubated at 80°C and pH 7.0. The enzymes are thermostable at temperatures between 60 and 80°C in the absence of substrate. Calcium is not required for thermostability. Cu2+, Hg2+ and EDTA inhibit the protease activity while Fe2+ and Fe3+ ions enhanced the activity. SDS-PAGE studies indicate the presence of multiple protease activity bands with molecular masses between 40 and 57 kDa. The proteases show higher activity towards short synthetic peptides while a decrease in specificity was observed with longer peptides.