Vibrio aestivus sp. nov. and Vibrio quintilis sp. nov., related to Marisflavi and Gazogenes clades, respectively

Abstract

Two new Vibrio species, Vibrio aestivus and Vibrio quintilis, are described after a polyphasic characterization of strains M22(T), M61 and M62(T), isolated from seawater collected off a beach on the East coast of Spain (Valencia). All three strains are Gram negative, mesophilic, slightly halophilic, fermentative rods. V. aestivus (M22(T)=CECT 7558(T)=CAIM 1861(T)=KCTC 23860(T) and M61=CECT 7559=CAIM 1862=KCTC 23861) is oxidase positive, reduces nitrates to nitrites, is negative for Voges Proskauer, arginine dihydrolase and indole and non hydrolytic on most substrates tested. The 16S rRNA gene sequences of M22(T) and M61 are most similar to Vibrio marisflavi (97.1-97.2%) but phylogenetic analysis using NJ, MP and ML methods display Vibrio stylophorae (96.2% similarity) as sibling species. The three species form a deep clade in the genus Vibrio. Average Nucleotide Identity (ANI) values, determined as a measure of overall genomic resemblance, confirmed that strains M22(T) and M61 are members of the same species, different to V. marisflavi CECT 7928(T). V. quintilis (M62(T)=CECT 7734(T)=CAIM 1863(T)=KCTC 23833(T)) is aerogenic, arginine dihydrolase and Voges Proskauer positive, oxidase negative and unable to reduce nitrate, traits shared by most species in the Gazogenes clade. It is unpigmented and does not grow on TCBS Agar. 16S rRNA gene similarities to its nearest species, Vibrio aerogenes and Vibrio mangrovi, are 97.6% and 96.0% respectively. Strain M62(T) and V. aerogenes CECT 7868(T) display ANI values well below the 95% boundary for genomic species.