Research Article SCREENING OF POTENTIAL PROBIOTIC LACTOBACILLUS STRAINS ISOLATED FROM FERMENTED FOODS, FRUITS AND OF HUMAN ORIGIN

Objective: To screen and characterize Lactobacillus strains having potential probiotic properties from fermented foods and fruits, and to investigate cell surface characteristics and antimicrobial activity against food-borne and gastrointestinal tract (GIT) pathogens. Methods and Results: In the present study, twenty five Lactobacillus strains were isolated from fruits, fermented foods and human origin on De Man Rogosa and Sharpe (MRS) agar plates and identified on the basis of their phenotypic characteristics and 16S rDNA sequencing. Isolated Lactobacillus strains tolerated inhibitory substances like bile (up to 4%), NaCl (up to 8%), phenol (up to 0.6%) and low pH (2.0). Six of the isolates exhibited inhibitory activity against food-borne and GIT pathogens by well diffusion method. The isolates appeared to possess hydrophilic cell surface as determined by microbial adhesion to n-hexadecane. Isolates auto-aggregated and also co-aggregated with pathogens tested. The isolates were not susceptible to antibiotics like vancomycin, tobramycin, kanamycin and norfloxacin while were highly susceptible to chloramphenicol, clindamycin, erythromycin, oleandomycin and penicillin G. None of the isolates showed haemolytic activity