Isolation and Characterization of Enterococci from Yoghurts of Bangladesh

Background: Bacteriocin - producing Enterococci have potential probiotic value. In this study, Enterococci possessing stable antibacterial activities were isolated from yoghurts of Bangladesh. Methods: Bacteria were isolated on MRS medium and genotyped based on partial 16S rDNA sequencing. Cultured supernatants were assessed for antibacterial activity by agar - well diffusion method before and after heat, proteinase K, and β - mercaptoethanol treatments. Results: In this study, 18 Enterococci bacteria were isolated from 10 different yoghurt samples of Bangladesh. Partial 16S rDNA genotyping suggested that these bacteria were either E. faecalis or E. faecium, or E. durans. Phylogenetic analysis suggested that these strains are closely related to other dairy Enterococci and distantly related to non - dairy Enterococci. Four isolates showed potent antibacterial activity against seven food - borne pathogens in vitro. The antibacterial property can withstand temperature as high as 90 oC for an hour, 1 µg/mL proteinase K, and 2.5% (v/v) β - mercaptoethanol treatments as well. Conclusions: These isolated yoghurt Enterococci have some probiotic value because of their stable antibacterial activities and further improvement of these Enterococci is necessary to improve yoghurt quality.