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RESEARCH PRODUCT

Influence of aquatic microbiota on the survival in water of the human and eel pathogen Vibrio vulnificus serovar E

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Summary The eel and human pathogen Vibrio vulnificus serovar E (biotype 2) is seldom isolated from natural waters, although it can survive in sterilized artificial seawater microcosms for years. The main objective of the present study was to investigate whether aquatic microbiota can limit its survival and recovery from water samples. A set of preliminary experiments of survival in microcosms containing natural seawater and water from eel farms showed that the persistence of this pathogen was mainly controlled by grazing, and secondarily by bacterial competition. The bacte- rial competition was further analysed in artificial seawater microcosms co-inoculated with selected virulent serovar E (VSE) strains and potential compet- itors. Competitors included V. vulnificus biotype 1 iso- lates and strains of selected species that can grow on the selective media designed for V. vulnificus isola- tion from water samples. Evidences of bacterial com- petition that was detrimental for VSE recovery were recorded. Thus, some species produced a deleterious effect on VSE strains under starvation, and others were able to use the resources more efficiently under nutrient input. These results suggest that an over- growth of more efficient competitor bacteria in con- ventional media used for isolation of V. vulnificus could mask the recovery of VSE strains and explain the scarcity of reports on the isolation of this human and eel pathogen from natural waters.