Study of beneficial properties and safety of Lactic Acid Bacteria (LAB) strains isolated from bovine mammary gland in Córdoba, Argentina

ESPECHE, MARÍA CAROLINA; FROLA, IGNACIO; PELLEGRINO, MATÍAS; BOGNI, CRISTINA; NADER-MACÍAS, MARÍA ELENA

Santiago de Chile

Congreso; XXVI World Buiatrics Congress; 2010

Bovine mastitis (BM) is one of the most important problems in the dairy farm. The therapy of this disease is generally based on the use of antibiotics that are not always effective and are responsible of the presence of residues in the milk and the increase of antibiotic-resistant strains. Probiotics products are a novel and valid alternative to the antibiotic medication. But, in the development of probiotic products, one of the requirements is the assessment of the safety of the potential beneficial microorganisms. With the aim of designing a probiotic product to prevent BM, 117 LAB were previously isolated from foremilk samples in different dairy farms in Córdoba-Argentine to study their beneficial properties and select those potentially probiotic. The objective of the present work was: a) to evaluate some beneficial properties as production of inhibitory substances and exopolysaccharide (EPS) by LAB previously isolated from raw milk samples, and b) to identify those potentially probiotic strains and study the presence of antibiotic resistance and virulence factors. The production of inhibitory substances was evaluated by the agar diffusion plate test and by agar-TMB plates. Eleven strains isolated from mastitis and two foodborne pathogens were used as indicators. The production of EPS was determined in MRS agar enriched with different sugar sources. Strains were pre-selected according to the results obtained and then genetically identified. Nine strains were able to inhibit three of the indicator strains by production of bacteriocin-like inhibitory substances. Most of the strains were able to produce hydrogen peroxide. Any of the strain was able to produce EPS. Only four different species were found after the identification, into the species Weisella cibaria, Pediococcus pentosaceus, Enterococcus hirae and E. faecium. One of these strains showed a vancomicin gene resistance. After this screening, a group of potentially probiotic strains are available, selected by their functional properties and their safety to be used as probiotics. These results will support the next step to further select those microorganisms that could be included in a local veterinary probiotic for the prevention of BM.