Optimization and partial purification of a protease produced by selected bacterial strains grown on trash fish meal substrate and its antagonistic property against bacterial pathogens

In the present study protease producing bacterial strains such as Bacillus cereus, Proteus mirabilis, Proteus vulgaris and Enterobacter aerogenes were isolated from spoiled fish and shrimp tissues. The isolated strains were individually inoculated into the formulated culture media supplied with various concentrations (2.5-20%) of trash fish (Odonus niger) meat powder as major substrate. Among the tested substrate concentrations, 5% substrate supplied medium favored maximum protease (3.82-5.13 IU ml−1) production. After optimization of substrate concentration, the organisms were tested individually for their protease production capacity at various pHs and temperatures. The results showed that all the tested strains were capable of producing high protease at pH 6 and 50 °C. The crude proteases produced by the tested organisms were individually purified by MLFTPP and ASBP methods. The partially purified enzymes were screened against few pathogenic bacterial strains, and it was observed that the enzyme produced by P. vulgaris exhibited the highest antibacterial activity with the inhibition zone ranged between 168.0±0.82 and 204.3±1.25 AU/ml. Further, the partially purified enzyme of P. vulgaris alone characterized through SDS-PAGE analysis and determined its molecular mass as 65.0 KDa.