Evaluation of Probiotic Characteristics of Bacteria Isolated from Fermented Foods

Probiotics have beneficial effects on the host's health and can be isolated from many food sources. Fermented foods are rich source of lactic acid bacteria that are beneficial microorganisms which help to decrease the levels of potentially pathogenic microorganism in the gastrointestinal tract. These lactic acid bacteria should possess certain characteristics to be used as a probiotic. The objectives of the study were to isolate, screen and evaluate the probiotic characteristics of lactic acid bacteria from fermented foods (Idli, Dosa, Dhokla, Jalebi, Kanji, and Shrikhand). Twenty one isolates were obtained out of which fourteen of them were gram positive and Catalase negative that are the characteristics of lactic acid bacteria which were selected for further probiotic evaluation. Five isolates showed tolerance to acidic conditions at pH 2, 3 and 4, such as prevailing in the stomach. Bile tolerance test disclosed that eleven isolates were able to tolerate 0.3% mean intestinal bile concentration. NaCl tolerance test revealed that four isolates tolerated NaCl concentrations (ranging from 4%,6%,8%,10%,12%). Five isolates were able to adhere to mucosal surface indicated by the hydrophobicity test. All isolates were able to produce lactic acid which was confirmed by the lactic acid estimation test. Three isolates were sensitive to tetracycline and kanamycin but resistant to ampicillin and rest others were resistant to ampicillin, tetracycline and kanamycin. DO4 which is a bacterial isolate obtained from batter of dosa was able to qualify all the above tests and can be used as a suitable probiotic candidate in future applications related to health.