Production dynamics of extracellular protease from Bacillus species

Abstract

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.