In vitro Probiotic Potential and Anti-cancer Activity of Newly Isolated Folate-Producing Streptococcus thermophilus Strains

Most probiotic strains commercially available today are lactic acid bacteria. Within this functional group, is a thermophilic species widely used as starter culture for a huge number of dairy products. Besides being rapid acidifiers, many strains are able to produce and release folate during growth but, unfortunately, they are seriously impaired during passage through the human gastrointestinal tract. In this work, we studied eight strains isolated from dairy environments in Italy, which already had shown good technological properties, to evaluate their possible probiotic potential and cytotoxicity against cancer cells . All strains were also evaluated for some health-related properties such as susceptibility to most common antibiotics, hemolytic activity, resistance to simulated gastrointestinal conditions, bile salts hydrolytic activity, production of folate, adhesion to HT-29 human colorectal adenocarcinoma cells and cytotoxic activity against cancer cells and production of biogenic amines. Results revealed that two fast acidifying strains were found to possess probiotic properties along with anticancer activity and production of folate. These properties resulted similar and, in some cases, superior to those of GG, a well-known commercial probiotic strain. These findings encourage further studies to evaluate the actual health benefits of these strains on the human host.