Vibrio variabilis sp. nov. and Vibrio maritimus sp. nov., isolated from Palythoa caribaeorum

Abstract

Two novel vibrio isolates (R-40492T and R-40493T) originating from the zoanthid Palythoa caribaeorum in Brazil in 2005 were taxonomically characterized by means of a polyphasic approach comprising multilocus sequence analysis (MLSA), DNA–DNA hybridization (DDH), ΔT m analysis and phenotypic characterization. Phylogenetic analysis based on 16S rRNA gene sequences showed that R-40492T and R-40493T fell within the genus Vibrio and were most closely related to each other with 99 % similarity; similarities of these two novel isolates towards Vibrio neptunius LMG 20536T, Vibrio coralliilyticus LMG 20984T, Vibrio nigripulchritudo LMG 3896T, Vibrio sinaloensis LMG 25238T and Vibrio brasiliensis LMG 20546T varied between 97.1 and 98.5 %. DDH experiments showed that the two isolates had less than 15 % relatedness to the phylogenetically most closely related Vibrio species. R-40492T and R-40493T had 55–57 % relatedness to each other. The ΔTm between R-40492T and R-40493T was 6.12 °C. In addition, MLSA of concatenated sequences (16S rRNA, ftsZ, gyrB, recA, rpoA, topA, pyrH and mreB; 6035 bp in length) showed that the two novel isolates formed a separate branch with less than 92 % concatenated gene sequence similarity towards known species of vibrios. Two novel species are proposed to accommodate these novel isolates, namely Vibrio variabilis sp. nov. (type strain, R-40492T = LMG 25438T = CAIM 1454T) and Vibrio maritimus sp. nov. (type strain, R-40493T = LMG 25439T = CAIM 1455T).