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Identificação e caracterização de isolados de staphylococcus : sua utilização como culturas de arranque em enchidos fermentados secos e fumados
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Resumo(s)
O objectivo deste trabalho foi caracterizar a microbiota estafilococica tecnológica obtida de produtos cárneos fermentados tradicionais e do ambiente fabril correspondente, a fim de avaliar o seu potencial uso como cultura starter. Cento e quatro isolados de Staphylococcus spp. previamente identificados por provas bioquímicas, obtidos de diferentes origens e pontos de colheita do ambiente fabril e chouriço de duas unidades fabris (A e B), localizadas no Sul de Portugal, foram submetidos a análise através de metodologias PCR para confirmação genética do gênero e espécies (S. xilosus, S. saprophyticus, S. equorum, S. carnosus e S. epidermidis). Dos quarenta e sete isolados de Staphylococcus pertencentes à Unidade Fabril A dominava o S. equorum enquanto os restantes cinquenta e sete pertencentes à Unidade Fabril B eram maioritariamente compostos por S. xylosus.
Os perfis genéticos dos isolados foram comparados por PCR fingerprinting e a análise por utilização do software BioNumerics levou à seleção de 43 Staphylococcus. Estas estirpes foram caracterizadas quanto à actividade nitrato redutase, actividade lipolítica e proteolítica, a fim de avaliar o seu interesse tecnológico. Trinta por cento das estirpes apresentaram actividade proteolítica, enquanto quarenta e dois por cento apresentaram actividade lipolítica. Quanto à actividade nitrato redutase verificou-se que cerca de 65% das estirpes estudadas reduzia o nitrato. Representantes seleccionados (n = 10) de grupos com perfil genético diferente foram caracterizados quanto à capacidade de crescimento em diferentes condições de temperatura, pH e concentração de cloreto de sódio, a fim de avaliar a sua utilização como cultura starter.
Estirpes de S. xylosus e S. equorum (n = 10) cresceram em todas as condições de análise sendo no entanto o mesmo mais efectivo a 15 ° C e 20 ° C, pH 5,5 a 20 °C e 10% e 15% de concentração de cloreto de sódio, encontrando-se assim garantidas as condições para a sua aplicação em processos tecnológicos com temperaturas variáveis.
As estirpes de S. carnosus P05-58 e S. equorum P05-74 da Unidade Fabril A e estirpes de S. xylosus P06-01 e P06-26, demonstaram ser, pelas suas características, as mais interessantes do ponto de vista tecnológico para serem utilizadas como flora iniciadora.
ABSTRACT - The aim of this work was to characterize the staphylococci technological microbiota obtained from traditional fermented dry sausages and the corresponding environment workshops, in order to evaluate their potential use as starters. One hundred and four Staphylococcus spp. isolates previously identified by biochemical tests, obtained from different sources and sampling points of the manufacturing environment and traditional fermented Portuguese sausage (chouriço) from two workshops A and B, located in Southern Portugal, were analyzed by PCR methods for genetic confirmation of genus and species (S. xilosus, S. saprophyticus, S. equorum, S. carnosus and S. epidermidis). Forty-seven staphylococci from unit A were allocated to the dominating species S. equorum while the remaining fifty-seven belonging to unit B were mainly composed of S. xylosus. The genetic profiles of the isolates were compared by PCR fingerprinting and the analyses using the BioNumerics software lead to the selection of 43 staphylococci. These strains were characterized for their nitrate reductase, lipolytic and proteolytic activity in order to evaluate their technological interest. Thirty percent of the strains showed proteolytic activity while forty-two percent had lipolytic activity. Regarding the nitrate reductase activity, it was found that about 65% of the strains under study reduced nitrate. Representatives of genetic profile groups (n=10) were also evaluated for growth capacity in different conditions of temperature, pH and sodium chloride concentration in order to evaluate their use as starter cultures. S. xylosus and S. equorum strains (n=10) grew under all the conditions under analysis however, they seem to be more successful at 15 ° C and 20 ° C, pH 5.5 at 20 ° C and 10% and 15% sodium chloride concentration, which guarantees their application in sausage technological processes with varying temperatures. From the technological point of view leading towards future application as starter cultures, the strains S. carnosus P05-58 and S. equorum P05-74, from workshop A, and strains S. xylosus P06-01 and P06-26, from workshop B, demonstrated to be the most interesting.
ABSTRACT - The aim of this work was to characterize the staphylococci technological microbiota obtained from traditional fermented dry sausages and the corresponding environment workshops, in order to evaluate their potential use as starters. One hundred and four Staphylococcus spp. isolates previously identified by biochemical tests, obtained from different sources and sampling points of the manufacturing environment and traditional fermented Portuguese sausage (chouriço) from two workshops A and B, located in Southern Portugal, were analyzed by PCR methods for genetic confirmation of genus and species (S. xilosus, S. saprophyticus, S. equorum, S. carnosus and S. epidermidis). Forty-seven staphylococci from unit A were allocated to the dominating species S. equorum while the remaining fifty-seven belonging to unit B were mainly composed of S. xylosus. The genetic profiles of the isolates were compared by PCR fingerprinting and the analyses using the BioNumerics software lead to the selection of 43 staphylococci. These strains were characterized for their nitrate reductase, lipolytic and proteolytic activity in order to evaluate their technological interest. Thirty percent of the strains showed proteolytic activity while forty-two percent had lipolytic activity. Regarding the nitrate reductase activity, it was found that about 65% of the strains under study reduced nitrate. Representatives of genetic profile groups (n=10) were also evaluated for growth capacity in different conditions of temperature, pH and sodium chloride concentration in order to evaluate their use as starter cultures. S. xylosus and S. equorum strains (n=10) grew under all the conditions under analysis however, they seem to be more successful at 15 ° C and 20 ° C, pH 5.5 at 20 ° C and 10% and 15% sodium chloride concentration, which guarantees their application in sausage technological processes with varying temperatures. From the technological point of view leading towards future application as starter cultures, the strains S. carnosus P05-58 and S. equorum P05-74, from workshop A, and strains S. xylosus P06-01 and P06-26, from workshop B, demonstrated to be the most interesting.
Descrição
Dissertação de Mestrado em Segurança Alimentar
Palavras-chave
Staphyloccocus coagulase negativa Produtos cárneos fermentados Starters Actividade proteolítica Actividade lipolítica Actividade nitrato redutase Staphylococcus coagulase negative Fermented meat products Starters Proteolytic activity Lipolytic activity Nitrate reductase activity
Contexto Educativo
Citação
Carvalho, L.M.C.P.Q. (2010). Identificação e caracterização de isolados de staphylococcus : sua utilização como culturas de arranque em enchidos fermentados secos e fumados. Dissertação de Mestrado. Universidade Técnica de Lisboa, Faculdade de Medicina Veterinária, Lisboa.
Editora
Universidade Técnica de Lisboa. Faculdade de Medicina Veterinária