Antibacterial Activity of Lactic Acid Bacteria isolated from Dairy Products against Enteropathogens

Lactic acid bacteria isolated from dairy products have received greater attention as potential food preservative due to their inhibitory activity against many food borne pathogens. In the present study, the antibacterial effect of 9 lactic acid bacteria isolated from milk (02), cheese (01) and curd (06) samples was investigated against five gram -ye bacterial isolates as Escherichia coli, Vibrio harveyi, Salmonella typhi and Klebsiella pneumonae by using agar well diffusion assay. The lactobacillus strain CC3 from curd sample showed maximum inhibitory activity against all selected test organisms. Growth profiles showed that maximum growth was observed at the end of late log phase and was accompanied with maximal reduction in pH of growth medium from 7.0 to 5.0. The strain CC3 was inoculated in soybean casein digest broth for four days and the cell free supernatant was assessed daily for production of bioactive compound. It was observed that the isolate showed highest activity against all test organisms at the end of 72 hrs. This preliminary work shows the potential application of lactic acid bacteria in development of new therapeutic agents that may have role in preservation of fermented food.