Isolamento, enumeração, identificação molecular e avaliação de propriedades probióticas de bactérias ácido-lácticas isoladas de leite de ovelha

• Ano de defesa: 2011
• Autor(a) principal: Leonardo Borges Acurcio
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: potencial probiótico; enterococos; leite de ovelha; Enterococcus; Probióticos; Leite de ovelha Análise; Bactérias produtoras de ácido láctico
• Link de acesso: http://hdl.handle.net/1843/BUOS-8NNFFX

Sheep milk, obtained from one of the oldest domestic animals, is unique for its high solids ratio. Its cheese are more famous than the milk itself. Lactic acid bacteria, abundant in milk from several mammals, include most of the probiotic microorganisms, which bring benefits to their consumers when ingested in viable and adequate portions. Few data are available in the literature on the microbiota of ewe milk as well on its possible probiotic features. Therefore, the objective of this work was to identify the species of lactic acid bacteria in milks from Lacaunes, Santa Inês and its breeds and evaluate their in vitro probiotic potential. The identification was made through Sangers 16S rDNA sequencing method. The identified species were Enterococcus faecium (56.25%), E. durans (31.25%) and E. casseliflavus (12.5%). Their probiotic potentialwas evaluated by gastric pH and biliary salt resistance and antimicrobial susceptibility; and antagonism against samples and reference microorganisms. It was observed that 75% of the tested enterococci were resistant to gastric pH (2.0) and 56.25% to 0,3% of oxgall (biliary salts). All the tested enterococci were resistant to ceftazidime, oxaciclin, and streptomycin and sensible to clindamycin, erythromycin, and penicillin. The resistance to ciprofloxacin, gentamicin, tetracycline, and vancomycin varied among the tested species. All the tested enterococci strongly inhibited Escherichia coli and Listeria monocytogenes samples, moderately inhibited E. faecalis and Staphylococcus aureus samples, and didnt inhibit Psedomonas aeruginosa, Salmonella enterica var.Typhimurium samples and also one E. durans sample isolated from the evaluated sheep milk. Four samples of E. faecium, one of E. durans, and one of E. casseliflavus presented the best probiotic potential. However, more studies are needed to prove that these samples dont carry neither virulence genes nor antimicrobial resistance genes, as well as their probable transmission to other microorganisms