Screening and Characterization of Lactic Acid Bacteria from Fermented Milk

In this study, different strains were isolated from the fermented milk in Vellore and were subjected to preliminary screening and 45 isolates were obtained and it was characterized and examined for the presence of probiotic properties like cholesterol assimilation, exopolysaccride production and antibiotic resistance. The cholesterol assimilation ranged from 28-83%, which is significantly highest and observed for the first time, and exopolysaccride varied from 16-89%. Further, resistance to 8 commonly used antibiotics $-lactans (penicillin, ampicilin), gram positive spectrum (vanomycin), broad spectrum (rifampin, trimethoprim) and aminogycosides (kanamycin, streptomycin, and bacitracin) was assessed by disk diffusion method. Among the selected 45 strains, 20, 20, 60, 70, 90 and 100% were found to be exhibiting a significant degree of resistance to kanamycin, trimetroprim, rifampicin, kanamycin, amphicilin and penicillin respectively. However, all strains were resistant to penicillin and 90% were resistant to ampicillin. Usually all Lactobacillus and Bifidobacterium strains were susceptible to $-lactum antibiotics but our isolates showed resistance which is contrary and new information to the previous investigation. Based on the above characters 7 isolates were considered to be best for probiotic applications. The strains thus obtained are under investigation for further studies.