Anti-proliferative effects of Enterococcus strains isolated from fermented dairy products on different cancer cell lines

Among the lactic acid bacteria, Enterococcus strains can be utilized as probiotic and preservative agents. Enterococcus strains from traditional Iranian dairy products were isolated, identified by sequencing 16s rDNA gene, and biologically characterized in this study. Primary assessments, including low pH and high bile salt tolerance tests and experiments on antagonistic activity against pathogens and antibiotic susceptibility, verified the probiotic property of strains. The secreted metabolites from the strains and Taxol, as an anti-cancer drug, were analyzed through MTT assay to investigate their cytotoxicity in different cancer (MCF-7, HeLa, HT29, and AGS) and normal human (HUVEC) cell lines. Results revealed the anticancer characteristics of the secreted metabolites of E. durans 39C against all cancer cell lines, similar to Taxol. The metabolites did not exhibit cell toxicity in the normal cell line. Fluorescent microscopy and flow cytometry confirmed that apoptosis is the main cytotoxic mechanism of E. durans 39C secretion metabolites.