Production dynamics of extracellular protease from Bacillus species

Screening and isolation of proteolytic bacteria were carried out from soil samples of Ikogosi warm spring (SW, Nigeria). Eighteen isolates were positive on skim milk agar (10%) of which fifteen produced protease in culture broth. Three isolates, identified as Bacillus macerans IKBM-11, B. licheniformis IKBL-17 and B. subtilis IKBS-10, were selected for further study. These Bacillus species could grow up to 65°C within a broad pH range of 5 to 10 with an optimal growth temperature and pH at 60°C and 8.0, respectively. For the three Bacillus species, protease production occurred between 37°C and 65°C and pH 5 to 10. Maximum growth and maximum enzyme production was observed at 48 h when grown in 50 ml medium (pH 8.0) under shaking condition at 60°C. The results showed that Bacillus species under study are good producers of extracellular protease at high temperature. This might be an indication that proteases produced would be thermostable.