Antimicrobial activity of enterocin obtained from Enterococcus durans on Shiga-like toxin-producing Escherichia coli / Atividade antimicrobiana de enterocina produzida por Enterococcus durans sobre Escherichia coli produtora de toxina Shiga-like

ABSTRACT: Shiga-like toxin-producing Escherichia coli (STEC) is an important source of food contamination that presents risks to human health. Several industrial food processes eliminate this microorganism; however, these processes can alter the characteristics of the product. Alternative methods of preservation have been identified as an option to control these foodborne pathogens. The purpose of this study was to evaluate the action of bacteriocins produced by Enterococcus durans MF5 in STEC cells. Cell-free supernatant (CFS) containing enterocins from the MF5 isolate was tested over different time points (6, 18, and 24 h). Enterocins present in the crude CFS showed inhibition against STEC at all time points. In the investigation of cell integrity, using propidium iodide and fluorescence microscopy, considerable cell death was observed within 6 h of the cells being in contact with the enterocins, which was also observed at the 18 and 24 h time points. These results showed that the enterocins produced by the MF5 isolate have potential use in the control of STEC.

RESUMO: Escherichia coli, produtora de toxina Shiga-like (STEC), apresenta riscos à saúde humana, constituindo uma importante fonte de contaminação na indústria de alimentos. Diversos processos industriais eliminam esse microrganismo, contudo podem alterar as características do produto. Métodos alternativos de conservação tem sido uma opção para controlar esse microrganismo de alimentos. O objetivo desta pesquisa foi avaliar a ação de bacteriocinas produzidas por Enterococcus durans MF5 em células de E. coli STEC. Foram utilizados sobrenadante livre de células (CFS) contendo enterocina, nos tempos 6, 18 e 24 horas de incubação. A enterocina presente no CFS bruto apresentou inibição contra E. coli STEC em todos os tempos testados. Na observação da integridade celular utilizando iodeto de propídio e observação em microscópio de fluorescência, observou-se que em 6h da célula em contato com a enterocina, já havia considerável morte celular, estendendo até os tempos de 18 e 24 horas. Os resultados obtidos mostraram que a enterocina produzida pelo isolado MF5 apresenta uso potencial no controle de E. coli STEC.

Biofilm formation by blood isolates of candida parapsilosis sensu stricto in the presence of a hyperglycidic solution at comparable concentrations of total parenteral nutrition

Abstract INTRODUCTION: Administration of total parenteral nutrition (TPN) via catheters increases the risk for candidemia from Candida parapsilosis. METHODS: C. parapsilosis sensu stricto blood isolates were evaluated for ability total biomass biofilm formation and morphogenesis in presence of glucose at TPN equivalent concentrations. RESULTS: Biofilms were increased at high glucose concentrations (25-30%) compared to the control medium. Significant increase in filamentous forms was observed in cultures with 30% glucose. CONCLUSIONS: Biofilm formation by C. parapsilosis sensu stricto in hyperglycidic medium may contribute to its pathogenic potential for fungemia related to TPN catheters.