Adesão de isolados de Listeria monocytogenes provenientes de linhas de processamento de carne bovina e caracterização por PFGE

• Ano de defesa: 2011
• Autor(a) principal: Galvão, Newton Nascentes
• Orientador(a): Nero, Luís Augusto
• Banca de defesa: Ferreira, Márcia de Aguiar
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Medicina Veterinária
• Departamento: Biotecnologia, diagnóstico e controle de doenças; Epidemiologia e controle de qualidade de prod. de
• País: BR
• Palavras-chave em Português: Listeria; Carne bovina; Controle de qualidade
• Palavras-chave em Inglês: Listeria; Beef; Quality control
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA
• Link de acesso: http://locus.ufv.br/handle/123456789/5066

Listeria monocytogenes is a foodborne pathogen and differs from other pathogens by its psycrotrophic characteristic, due to its ability of growing at refrigerator temperatures. This pathogen is also known as resistant to pH changes and different concentrations of NaCl. However, its main form of resistance is conferred by its ability to adhere and form biofilms. In this work, besides studying the adhesion of L. monocytogenes in different culture conditions, we performed a molecular technique, pulsed‐field gel electrophoresis (PFGE), to characterize distinct cultures isolates from beef processing plants. First, tests were conducted to evaluate the adhesion of L. monocytogenes cultures using a method with microtiter plates considering distinct inoculums concentrations. In a second step, the adhesion ability was evaluated considering distinct culture media (brain‐heart infusion ‐ BHI, trypticase soy broth ‐ TSB, beef extract ‐ BE, all at their usual composition and diluted at 1:10), carbohydrate sources (rhamnose, glucose, fructose and maltose), NaCl concentrations (0.5%, 2.5%, 5.0%, 7.5% and 10.0%), pH (5.0, 7.0 and 9.0), and incubation temperatures (4 °C, 10 °C, 25 °C and 35 °C). After assessing the adhesion of Listeria monocytogenes, will be performed pulsed field gel electrophoresis to assess the genetic profile of each isolate. With this technique, we can classify the isolates according to their profiles and to correlate the enzymatic capacity to adhere to the origin in the processing of beef. Considering the initial results, all cultures were tested at 108 CFU/mL e classified as their adhesion ability: weak (8 cultures), moderate (17) and strong (4). The cultures presented higher adhesion ability at non‐diluted cultures media (mainly brain and heart infusion), pH 7.0, incubation at 25 and 37 °C, and NaCl concentrations of 5 and 7%. No relevant differences were observed for adhesion considering the distinct carbohydrate sources. The cultures were characterized by PFGE, using AscI and ApaI as restriction enzymes. The analysis identified two clusters for serotypes 4b and 1/2a with similarities of 48% and 68% respectively, evidencing the persistence of some strains in the environment of beef production and processing. The obtained results indicated that the adhesion of L. monocytognes is related to their optimal growing conditions, despite a wide variation of characterized pulsotypes.