Complete genome sequence of a winter season facilitates discovery of a novel subclade of cold-adapted species in the clade.

In temperate marine climate zones, seasonal changes in water temperature contribute to distinct populations of warm- and cold-water vibrios. We report here the complete genome sequence (BUSCO score=94.8) of the novel strain sp. VB16 isolated in late winter from the intertidal zone near Virginia Beach, Virginia, USA with the ability to form colonies at 4 °C. The 5.2 Mbp genome is composed of a large (3.6 Mbp) and small (1.6 Mbp) chromosome. Based on paired average nucleotide identity (ANI), average amino acid identity (AAI) and digital DNA-DNA hybridization (dDDH), sp. VB16 is the same species as . sp. UBA2437 from a North Sea tidal flat and is closely related to . sp. DW001 from Antarctic sea ice. Our phylogenomic and bioinformatic analyses placed VB16, UBA2437 and DW001 into a cold-tolerant subclade within the clade, along with two non-cold-tolerant subclades. Orthovenn analysis indicated that VB16 and its other clade members shared 1544 gene orthologue clusters, including clusters for biosynthesis of polar flagella and tight adhesion pili that predict multiple lifestyles, either free-living or as an opportunistic pathogen within a marine eukaryotic host. The cold-tolerant subclade shared 552 orthologue proteins, including genes known to promote survival in cold or freezing temperatures, such as the eicosapentaenoic acid biosynthetic gene cluster, exopolysaccharide gene cluster and novel giant proteins with ice-binding domains. This subclade represents a group of psychrotolerant or 'moderate psychrophile' winter season species. The discovery of this subclade opens the door for experimental work on the physiological features, virulence potential and ecological importance of this subclade.