CONICET | Buscador de Institutos y Recursos Humanos

ISOLATION OF Bacillus FROM NEWBORN CALVES. PRELIMINARY EVALUATION OF THEIR PROPERTIES FOR THEIR INCLUSION IN PROBIOTIC PRODUCTS Natalia C. Maldonado, Clara V. Silva de Ruiz, María Elena F Nader-Macías Probiotics are used as viable microorganisms for animal feed, improving the intestinal microbial balance and preventing diarrheal diseases. Although bacteria from the genus Bacillus are used for technological applications, a few years ago has been proposed as an alternative for probiotic use, mainly by their spore forming characteristic. Probiotic products containing spores offer advantages over probiotics with vegetative cells by the longer storage time and their survival to the Gastro Intestinal Tract (GIT) conditions. The aim of this work was to isolate and select microorganisms of the genus Bacillus from new born calves, for their inclusion in a potential novel probiotic product that could prevent diarrheic processes by improving the establishment of the indigenous microbiota in the GIT. The samples were obtained from calves ranged from 0 to 4 months old. Nine Bacillus strains were isolated from faeces and 1 from the oral cavity. The strains were identified by phenotypic characteristics as catalase activity, type of haemolysis, lecitinase activity, anaerobic growth, acid production from glucose, nitrate production, gelatine and casein hydrolysis and growth in 7% NaCl. Two of the strains were identified as Bacillus subtilis, 1 as Bacillus cereus and the others as Bacillus sp. The Bacillus subtilis strains were selected for further studies. The surface properties were determined in spore and comparatively with vegetative cells. The autoaggregation degree was studied after two hours incubation. The hydrophobic nature of the cell surface was studied through the MATH (Microbial Adhesion to Hexadecane) technique. Neither the vegetative cells nor the spores assayed showed autoaggregative patterns. In contrast, the spores showed to be more hydrophobic than the vegetative cells in all the strain studied. The peroxide production was assayed by the plate technique with TMB (tetramethyl-benzidine). None of the strains were able to produce peroxide by this plate method. The production of inhibitory substances was assayed against Y enterocolitica, E coli, S Dublin, S infantis, S enteritidis, S thyphimurim, Klebsilella sp, B cereus, S areus, S epidermidis and St uberis by the plate diffusion method. All the Bacillus supernatants hardly inhibited the growth of the Gram positive strains assayed. The biosurfactant production was studied by the drop collapse technique and the emulsification capacity by the Cooper technique by using hexadecane for the disperse phase. Only one of the assayed strains shared these properties. The strains selected will be further studied to evaluate their beneficial characteristics for their potential inclusion in a probiotic product for the prevention of newborn calves diarrhea. Also, the combination of bacteria including spore-forming bacilli and lactobacilli could be applied in the design of a new product to be use in animal nutrition for dairy farms.