Isolation and screening of Bacillus sp. strains for biosynthesis of protease from wastewater

Abstract

Abstract: From 6 wastewater samples, after heating, we have isolated 47 different bacterial strains, of which 16 strains have been preliminarily identified in genus Bacillus according to Bergey 's classification key (1957); and designated as B1 to B16. Research results show that all 16 strains are capable of biosynthesis of extracellular protease by gelatin hydrolysis ring size determination with HgCl2 reagent 10%, of which 4 strains B6, B8, B9, B14 with the diameter of hydrolysis rings are 14.33; 18.33; 16.67 and 18.67 mm, respectively were selected to determine enzyme activity following Sigma method. At pH 7.9 with 1% gelatin inducers, after 24 hours of liquid fermentation at 30^oC, strain B14 showed the highest activity (175.2 UI / ml), followed by strain B6 (130.1) UI / ml). After 36 hours of culture, the maximum protease activity of B6 and B14 strains were 170.2 (UI / ml) and 200.2 (UI / ml), respectively.