Vibrio agarilyticus sp. nov., an agar-digesting marine bacterium isolated from coastal seawater in Daya Bay (Guangdong, China)

Abstract

A Gram-strain-negative, facultatively anaerobic, motile, rod-shaped and flagellated marine bacterium, designated SM6T, was isolated from surface seawater collected in Daya Bay (Guangdong, China). Phylogenetic analysis based on 16S rRNA gene sequences, multilocus sequence analysis, phylogenomic analysis of single-copy gene families and whole genome data showed that strain SM6T belonged to the genus Vibrio . The closest phylogenetic relatives of SM6T were Vibrio plantisponsor MSSRF60T (97.38 % 16S rRNA gene sequence pairwise similarity), Vibrio variabilis R-40492T (97.27 %), Vibrio aestuarianus ATCC 35048T (97.21 %) and Vibrio sagamiensis LC2-047T (97.3 %). Growth of strain SM6T occurred at 10–45 °C (optimum 30 °C), at pH 6.0–9.0 (optimum 6.0) and in the presence of 0–10 % (w/v) NaCl (optimum 3–8 %). The predominant fatty acids (>10 %) were summed feature 3 (C16 : 1 ω7c or/and C16 : 1 ω6c), C16 : 0 and summed feature 8 (C18 : 1 ω7c or/and C18 : 1 ω6c). The DNA G+C content of the assembled genomic sequences was 47.37 % for strain SM6T. Average nucleotide identity values between SM6T and its reference species were lower than the threshold for species delineation (95–96 %); in silico DNA–DNA hybridization further showed that the strains shared less than 70 % similarity. On the basis of evidence from the present polyphasic study, strain SM6T is considered to represent a novel species of the genus Vibrio , for which the name Vibrio agarilyticus sp. nov. is proposed. The type strain is SM6T (=KCTC 82076T=MCCC 1K04327 T).