Fatores de virulência de Bacillus cereus isolado na cadeia produtiva do leite na microrregião de Viçosa, Minas Gerais

• Autor(a) principal: Barreto, Jorge Mario Olivar
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2907
• topic: Qualidade do leite; Bacillus cereus; Enterotoxinas; Fatores de virulência; Quality of milk, Bacillus cereus; Enterotoxins; Virulence factors; CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::CIENCIA DE ALIMENTOS

The occurrence of Bacillus cereus in the production chain of raw milk and virulence factors associated with diarrheal toxicity was evaluated in two production systems, one technified another one no- technified. Initially, the micro-organism was isolate in selective medium MYP (Mannitol-Egg Yolk-Polymyxin) from storage tanks of milk, churn, hand milker, air and water and milk samples. One hundred and sixteen isolates of Bacillus spp. showed lecithinase activity and not fermented mannitol and were submitted to Gram stain and biochemical tests. Of the 116 isolates, 32 showed results characteristic of B. cereus in the tests performed and were subjected to molecular biology tests. The 32 isolates were subjected to analysis of PCR (Polymerase Chain Reaction) to detect the gyrB gene. In all isolates was amplified a 352pb product that after digestion using the restriction enzyme RsaI and had sizes of approximately 250pb. According to the literature data, they are identificated as Bacillus cereus. In the analysis of virulence factors, in 15 isolates (47%) were amplified segments of DNA from 761pb, indicating the occurrence of toxin producing gene non-hemolytic (NHE). Also, it were found in 7 (22%) of 32 isolates segments of DNA of 421 pb, demonstrating the presence of the gene encoding citotoxin K (CytK). Bacillus cereus NHE and, or, CytK positives were isolated from all sources of contamination evaluated in both systems of milk production, although there was a higher prevalence of the NHE gene. Analysis of 14 isolates positive for NHE or CytK genes showed conserved sequences similar to that of Bacillus cereus ATCC 14579 used as a reference, indicating that these isolates have the potential pathogenic.