LACTOBACILLUS STRAINS AS BIOLOGICAL CONTROL AGENTS IN THE RED-LEG SYNDROME IN Rana catesbeiana HATCHERIES

SERGIO ENRIQUE PASTERIS; BUHLER, M.; NADER-MACÍAS, M. E.

Jaen

Congreso; FOOD SAFETY UNDER EXTREME CONDITION: A CONFERENCE ON SMALL-SCALE PRODUCTION UNITS OF TRADITIONAL FERMENTED FOOD; 2004

Rana catesbeiana meat is one of the delicatessen in international gastronomy that have increased the worldwide consumption. However, their by-products such as liver, gut and skin are required for other industries. These facts implicate an intensive production process of R. catesbeiana litter in which the animals are more sensitive to diseases such as red-leg syndrome (RLS) being Proteus vulgaris and Pseudomonas aeruginosa the species implicated. This is the main cause of high mortality rates in hatcheries with serious impact on the production cost, also by the sanitization and therapeutic treatments implicated. In the last years, the concept of using probiotics products containing beneficial microorganisms to prevent diseases in humans and animals are widely studied and formulated to prevent intestinal, urogenital and respiratory infections. The aim of this work was to study the bacterial microflora of R. catesbeiana  hatcheries at different seasonal periods and to perform studies to determine the inhibitory properties of the isolated Lactobacillus on bacteria related with RLS. The results indicated that bacterial microflora varied with the annual period and hatchery area studied (water, aliments, skin of sick and normal animals). Enterobacteriaceae, Lactobacillus, Microcococcus, Enterococcus, Sreptococcus and Pediococcus were isolated from tadpoles, fattening phase animals, reproducers, water and food samples. These population varied with the seasonal period without differences between animal ages, being Lactobacillus the dominant genus. Sick adult animals showed skin ulcerations with bacterial translocation and structural alterations in liver and spleen. Histological studies performed in ventral abdominal ulceration did not show the presence of sporangia related with chytridiomycosis. One hundred isolated Lactobacillus sp strains were tested for inhibitory activity against homologous Enterobacter spp., Staphylococcus aureus, P. vulgaris and heterologous P. aeruginosa and Listeria monocytogenes Scott A strains. Ninety Lactobacillus strains inhibited the pathogens studied. Preliminary studies on nine of these strains demonstrated that the inhibitory effect could be related with organic acids and/or hydrogen peroxide production.   Key words: Lactic Acid Bacteria, Probiotics, Red-Leg Syndrome, Rana catesbeiana