Screening on Proteolytic Activity of Lactic Acid Bacteria from Various Yogurts and Fermented Milk

Proteases are necessary for living organisms; they are ubiquitous and found in a wide diversity of sources. Proteases are the key enzymes in industrial application. Microbial protease plays an important role in biotechnological process. In this paper the focus of this study is screening on Proteolytic activity of lactic acid bacteria from various yogurts and fermented Milk. Lactic acid bacteria were isolated from various yogurts and fermented milk by culturing on specific media and pure culture was obtained by sub-culturing. A total of 13 isolated strains was confirmed by Gram’s staining and identified by different biochemical tests and their ability to ferment different carbohydrates. They were screened for proteolytic activity on skim milk agar by the agar – well diffusion method. All of isolated strains showed the proteolytic activity. Among them, five isolated strains namely, L1, L2, L6, L7, L9 showed the widest clear zones formation after incubation time 24 hrs, 48 hrs, 72 hrs at 37°C. The result obtained in the present study indicated that the widest clear zones were produced at 48 hrs and 72 hrs of incubation period at 37°C. Thus, these bacterial strains were selected for further study.