RESUMO
Vibrio sp., ubiquitous in the aquatic ecosystem, are bacteria of interest because of their involvement in human health, causing gastroenteritis after ingestion of seafood, as well as their role in vibriosis leading to severe losses in aquaculture production. Their ability to enter a viable but non-culturable (VBNC) state under stressful environmental conditions may lead to underestimation of the Vibrio population by traditional microbiological enumeration methods. As a result, using molecular methods in combination with EMA or PMA allows the detection of viable (VBNC and culturable viable) cells. In this study, the impact of the EMA and PMA was tested at different concentrations on the viability of several Vibrio species. We compared the toxicity of these two DNA-binding dyes to determine the best pretreatment to use with qPCR to discriminate between viable and dead Vibrio cells. Our results showed that EMA displayed lethal effects for each strain of V. cholerae and V. vulnificus tested. In contrast, the concentrations of PMA tested had no toxic effect on the viability of Vibrio cells studied. These results may help to achieve optimal PMA-qPCR methods to detect viable Vibrio sp. cells in food and environmental samples.
Assuntos
Antibacterianos/farmacologia , Azidas/farmacologia , Propídio/análogos & derivados , Vibrio cholerae/efeitos dos fármacos , Vibrio vulnificus/efeitos dos fármacos , Ecossistema , Gastroenterite/microbiologia , Gastroenterite/prevenção & controle , Humanos , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Propídio/farmacologia , Reação em Cadeia da Polimerase em Tempo Real/métodos , Microbiologia da ÁguaRESUMO
AIMS: To finalize an effective and reproducible electroporation procedure to transform Oenococcus oeni ATCC BAA-1163 strain. METHODS AND RESULTS: The vector pGID052 was selected to optimize the electroporation procedure. Transformation efficiency was 5.8 x 10(3) per microg of DNA. Transformation was improved when competent cells were prepared with exponential phase cultures; optimum electroporation parameters were an electric pulse of 125 kV cm(-1), under a resistance of 200 omega and the presence of 10% (v/v) ethanol in the electroporation buffer (EPB). CONCLUSIONS: An effective protocol to transform O. oeni ATCC BAA-1163 strain by electroporation has been obtained by addition of ethanol to the EPB. A heterologous expression was obtained in O. oeni ATCC BAA-1163 by introducing a recombinant vector encoding a truncated form of ClpL2 protein. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of a successful electroporation of O. oeni ATCC BAA-1163. The major improvement was the addition of ethanol to the EPB, which has never been reported before as means of enhancing the incorporation of foreign DNA molecules into prokaryote cells by electroporation. This method constitutes a useful tool for the genetic study of this lactic bacterium.