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Effects of Enterococcus faecalis UGRA10 and the enterocin AS-48 against the fish pathogen Lactococcus garvieae. Studies in vitro and in vivo
- Baños, Alberto, Ariza, Juan José, Nuñez, Cristina, Gil-Martínez, Lidia, García-López, J. David, Martínez-Bueno, Manuel, Valdivia, Eva
- Food microbiology 2019 v.77 pp. 69-77
- Enterococcus faecalis, Lactococcus garvieae, Oncorhynchus mykiss, adverse effects, antibiotics, aquaculture, bacteriocins, biosafety, coculture, culture media, diet, dipping, disease control, minimum inhibitory concentration, pathogens, protective effect, survival rate, toxicity
- The aim of this study was to evaluate the effects of Enterococcus faecalis UGRA10 and its enterocin AS-48 against the fish pathogen Lactococcus garvieae. The minimum bactericidal concentrations of AS-48 against L. garvieae CECT 5807, 5806, and 5274 were 15.62, 15.62, and 7.81 μg/ml respectively. In broth cultures, enterocin at 100, 50, and 25 μg/ml reduced 108 CFU/ml lactococci after 2, 5, and 10 h, respectively. In co-cultures of UGRA10/L. garvieae at a 1/10 CFU/ml ratio, lactococci were eliminated after 24 h. Studies on UGRA10 biosafety and AS-48 toxicity in R1 cells and in rainbow trout have shown a lack of adverse effects from both the strain and bacteriocin. Trout challenged with L. garvieae and UGRA10 administered in diet 30 days before infection had a cumulative survival rate of 50% compared with 0% for control fish. Trout inoculated with the pathogen and treated by regular dipping in AS-48 baths had a survival rate of 60% after 20 days compared with that of untreated fish (0%). These results indicate the protective effect of the UGRA10 strain and the bacteriocin AS-48 against L. garvieae and the potential of these natural products as alternatives to antibiotics for controlling diseases in aquaculture.