Probiotic Potentiality from Versatile Strains as Resource to Enhance Freshwater Fish Health.

Dietary probiotic supplementation has the potential to enhance the health of fish and their disease resistance. In this study, some properties of ten strains have been evaluated, for their potential use as probiotics in freshwater fish diet. In particular, antimicrobial activity, antioxidant activity, the potentiality to survive the gastrointestinal transit and persist in the intestine, were evaluated in vitro. The experimental tests were carried out at 15 °C and 30 °C to determine the suitability of these lactic acid bacteria to be used as probiotics in the diet of fish grown at different temperatures. The results demonstrated that the evaluated strains, which often have significant differences among themselves, are characterized by important functional characteristics such as cell surface properties (auto-aggregation and hydrophobicity), ability to produce antioxidant substances, capacity to survive in the presence of 0.3% bile salts and acidic environment (2.5 pH), antagonistic activity against some fish opportunistic pathogens (, , and ) and other unwanted bacteria present in fish products ( and ). The outcomes suggest that these strains may be candidates as probiotics in warm- and cold-water aquaculture.