Population genetic and evolution analysis of Vibrio isolated from Turkish fish farms

Abstract

The genus Vibrio includes important pathogenic species for human and aquatic organisms such as Vibrio cholera, V. parahaemolyticus, V. vulnificus, V. anguillarum or V. harveyi. At present, Vibrionaceae family consists of >190 described species, classified into nine genera. Vibrio are widespread in shellfish, finfish and marine ecosystems and show resourceful ecologies, which recognized as one of the most diverse bacterial groups for illuminating the genome evolution. In the present study, to clarify the relationship among aquatic species in the genus, a multilocus sequence analysis (MLSA) and typing (MLST) approach was applied to characterize 51 Vibrio isolates from Turkish fish farms, 146 strains deposited in the PubMLST database and 59 type strains from GenBank. For all studied isolates (n = 256), diversity analysis, population structure, determination of recombination, demographic history and gene flow were performed based on the MLST scheme. Vibrio isolates, subjected to the study, showed a high diversity within the Vibrio population and also genetic interactions into the genus. We found 17 new described sequence types by MLST analysis that were isolated from rainbow trout, sea bream and sea bass in Turkish fish farms, which clearly indicate that the genes underwent recombination frequently. While predominant sequence types were found in the presented study, differences of genotypes need to be evaluated in a disease situation or preventing measurements. The findings about genetic recombination possibly helps to understand differences of Vibrio infections in fish. Furthermore, elucidating of genetic variability within species shed light on providing effective measurements in aquaculture by vaccine production and drug applications