Screening of in vitro Antimicrobial Potential of Fermentation Extracts Prepared from Indigenous Lactobacillus Isolates

Recently, efforts are being made to efficiently employ the probiotic bacteria in non-dairy products either as supplemental additive or for fermentation which might have several advantages over the probiotic dairy products such avoiding milk protein allergies, lactose intolerance or hyper cholesterolemia. So the present study aimed at screening of certain indigenous lactobacillus species responsible with antimicrobial potential against common pathogenic microorganism when allowed to ferment in liquid culture medium. The indigenous Lactobacillus spp. were isolated using different dairy samples like milk, curd, butter milk, cheese etc., on selective MRS agar medium and pure cultures were partially identified referring Bergey’s Manual of Systematic Bacteriology based on morphological, cultural and biochemical reactions. The selected pure cultures were allowed to ferment in MRS broth for 7 days at 37oC in with intermittent shaking of culture flasks. There were total 14 isolates of Lactobacillus spp. were obtained. According to the results of biochemical tests as described in table 1 the probability of LAB would have been L.acidophilus, L.fermentum, L.plantarum, L.casei, L. ruteri or L.rhamnosus. Out of the 14 indigenously isolated Lactobacillus spp., the cell free fermentation extract of the isolates LB-2, LB-3, LB-5, LB-6, LB-7, LB-9, LB-11, LB-12, LB-13 and LB-14 was found imparted antimicrobial activity over the test microbial species including Escherichia coli (MTCC-1687), Pseudomonas aeroginosa (MTCC-*1934), Staphylococcus aureus (MTCC-737) and Candida albicans (MTCC-227), due to unknown substances secreted within fermentation extract. The ability to produce antagonistic substances during the process of fermentation could be explored extensively for identification, purification and use in food preservation at both domestic as well as industrial levels. Keywords: Therapeutics, Antimicrobial activity, Lactobacillus, Fermentation extract