OPTIMIZATION OF PROTEASE PRODUCTION FROM BACTERIA ISOLATED FROM SOIL

Microbial proteases contribute nearly 40% of the total worldwide enzyme market. Hence, with the view of this significance, objective of the present study was to isolate and optimize the protease production from soil borne bacteria. Soil is the ideal habitat for many extracellular enzyme producing bacteria therefore soil samples were collected from two different sites of Banasthali University and bacteria were isolated by serial dilution agar plate technique. Isolated bacteria were screened on gelatin agar medium for proteolytic activity. Based on the results of primary screening 4 bacterial isolates from soil sample 1 and 4 bacterial isolates from soil sample 2 were selected for protease production in production medium. Four bacterial isolates from soil sample 1 were named as AKS-1, AKS-2, AKS-3 and AKS-4, respectively. Four bacterial isolates from soil sample 2 were named as AKS-5, AKS-6, AKS-7 and AKS-8, respectively. Isolate AKS-4 exhibited maximum protease activity (44.89 U/mL) after 48 h of incubation and isolate AKS-2 was producing minimum protease activity (2.37 U/mL) after 72 h of incubation. Isolate AKS-6 exhibited maximum protease activity (37.94 U/mL) after 3 days of incubation and isolate AKS-8 was producing minimum protease activity (1.22 U/mL) after 3 days of incubation. Hyper producing isolates (AKS-4 and AKS-6) from both soil samples were selected for optimization study. The optimum conditions for protease production by isolate AKS-4 were found to be at pH 8.5 after 5 days of incubation using glucose as carbon source and casein as nitrogen source. Maximum yield of enzyme was obtained by isolate AKS-6 at pH 10.5 after 5 days of incubation using starch as carbon source and casein as nitrogen source. Among all studied bacterial isolates, the maximum protease activity (52.29 U/mL) was recorded in isolate AKS-4 after optimization of culture conditions.