Isolation and Evaluation of Extracellular Protease Producing Bacteria

Abstract

In the present study, bacteria strains capable of producing protease were isolated and protease activity and stability were assessed under different pH and temperature conditions. Four bacterial isolates (B1-B4) were found to have proteolytic activity on skim milk agar plates. Time course studies indicated that strains Bl, B2 and B3 had the highest protease activity (36, 50 and 57 U/ml respectively for Bl, B2 and B3) after 24 h of incubation and strain B4 had the highest protease activity (35 U/ml) after 18 h of the incubation. The highest protease activity (100%) was found at pH 6 in strains Bl, B2 and B4 and at pH 8 in strain B3. However, the strains Bl and B3 showed optimum pH stability at pH 8, whereas strains B2 and B4 showed optimum pH stability at pH 7 and 6 respectively. The protease was active between 30 - 80°C with an optimal activity at 50°C except the strain B4 which recorded optimal protease activity at 40°C. The protease produced by all the isolated strains showed temperature stability at room temperature (30°C).