Equid milk: a well of safe probiotic bacteria and their metabolites with antioxidant properties

The human exposome represents an intriguing gene-environment interactions. Since the food is one of the most easily manageable human exposure, the serach for food items that might have beneficial properties to human health is of high importance. This study aimed to assess the probiotic potential and the antioxidant properties of a new indigenous probiotic bacteria isolated from equid (ili donkey) milk, known for its beneficial properties for ages. DPPH scavenging ability of live cells was determined and compared to antioxidant standard (L-ascorbic acid). Furthermore, the antioxidant activity of extracellular bacterial metabolites, with molecular mass smaller than 2000 daltons (Da) that can cross the epithelial barrier was assessed accompanied by the investigation of cytotoxic and genotoxic effect of metabolites on peripheral blood lymphocytes. The battery of tests showed excellent probiotic potential. The DPPH free radical scavenging activity of L. plantarum M2 cells was 7.25%. The tested bacterial media fraction removed 4.84% for L. plantarum M2 and L-ascorbic acid (20 mg/L) as a positive standard removed 56.41% of free radicals. Examined metabolites exhibited no cytotoxic effects on peripheral blood mononuclear cells which was detected by acridine orange/ethidium bromide vital staining compared to controls. The results of comet assay also did not show inducton of primary DNA damage of peripheral blood mononuclear cells exposed to bacterial extracellular metabolites. Taken together, we managed to present a new bacteria from donkey milk with excellent probiotic potential. Furthermore it does not posses any toxic properties so we confirmed Qualified Presumption Safety Status. The next steps in research will try to elucidate its possibility of minimising effects of mutagens found in food.