Identificação e agrupamento genético por MLST e PFGE de isolados bacterianos obtidos de fazendas da região do Campo das Vertentes, Minas Gerais

• Ano de defesa: 2012
• Autor(a) principal: Luiz, Lívia Maria Pinheiro
• Orientador(a): Carvalho, Antônio Fernandes de
• Banca de defesa: Pinto, Cláudia Lúcia de Oliveira , Nero, Luís Augusto , Cunha, Luciana Rodrigues da
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Ciência e Tecnologia de Alimentos
• Departamento: Ciência de Alimentos; Tecnologia de Alimentos; Engenharia de Alimentos
• País: BR
• Palavras-chave em Português: Propionibacterium; Biodiversidade; Probiótico; Bacteriocina
• Palavras-chave em Inglês: Propionibacterium; Biodiversity; Probiotic; Bacteriocin
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::CIENCIA DE ALIMENTOS
• Link de acesso: http://locus.ufv.br/handle/123456789/467

Brazil is the sixth largest milk producer in the world and the State of Minas Gerais is the largest milk and cheese producer of the country. The milk from different regions of the State contains a diverse endogenous microbiota, and it can provide different sensorial characteristics of products made from this milk. The aim of this work was to identify part of the autochthonous mesophilic microbiota isolated from raw milk, soil and silage from six milk producer farms in the Campo das Vertentes region in Minas Gerais State and to group the bacteria genetically From 200 isolates initially characterized by Gram staining and catalase test, 50 were identified to the species level by genotypic techniques using species-specific PCR and sequencing of 16S rDNA. The clonal diversity of isolates belonging to the genera Lactococcus and Enterococcus were determined by PFGE technique. The phylogenetic relatedness of Lactococcus lactis subsp. lactis was observed by MLST technique. In addition, we compared the discriminatory power of MLST and PFGE techniques, using strains of L. lactis subsp. lactis as a basis for comparison. The molecular characterization of the isolates led to identification of four genera of lactic acid bacteria: Lactobacillus, Leuconostoc, Enterococcus and Lactococcus, and also species belonging to the genus Staphylococcus. Among the LAB genera, Lactococcus and Enterococcus grouped most of the isolates found; isolates of L. lactis were present in a large number of samples, mainly from raw milk. The clonal diversity of isolates belonging to the genus Lactococcus showed a significant variability, since 10 L. lactis subsp. lactis strains were grouped into four different groups. For the Enterococcus isolates, we did not observe any variability. Isolates from different properties, were concentrated in the same group, indicating that these endogenous strains are dominant in the region. The MLST technique allowed us to observe and characterize the phylogenetic relationships among L. lactis subsp. lactis strains grouping them into different ST. By this technique, one can associate the different ST with industrial-technological characteristics, enabling the application of these strains as starter cultures.