Patiriisocius marinistellae gen. nov., sp. nov., isolated from the starfish Patiria pectinifera, and reclassification of Ulvibacter marinus as a member of the genus Patiriisocius comb. nov.

Abstract

A marine strain, designated KK4T, was isolated from the surface of a starfish, Patiria pectinifera, which was collected from seawater off the coast of Hokkaido, Japan. Strain KK4T is a Gram-stain-negative, non-spore-forming, rod-shaped, aerobic bacterium that forms yellow-pigmented colonies. A phylogenetic relationship analysis, based on 16S rRNA gene sequences, revealed that strain KK4T was closely related to Ulvibacter marinus IMCC12008T, Ulvibacter antarcticus IMCC3101T and Ulvibacter litoralis KMM 3912T, with similarities of 96.9, 95.8 and 95.6 %, respectively, but low sequence similarities (<94 %) among other genera in the family Flavobacteriaceae . Genomic similarities between strain KK4T and the three Ulvibacter type strains based on average nucleotide identity and digital DNA–DNA hybridization values were lower than the species delineation thresholds. Moreover, phylogenetic tree based on genome sequences showed that strain KK4T was clustered with U. marinus IMCC12008T and formed a branch independent from the cluster including type species of the genera Ulvibacter , Marixanthomonas , Marinirhabdus , Aureitalea and Aequorivita . Amino acid identity values between strain KK4T/ U. marinus IMCC12008T and the neighbour type species/strains were 61.9–68.2% and 61.5–67.4 %, which were lower than the genus delineation threshold, implying the novel genus status of strain KK4T. Strain KK4T growth occurred at pH 6.0–9.0, 4–30 °C and in NaCl concentrations of 0.5–5.0 %, and optimally at pH 7.0, 25 °C and 3.0 %, respectively. Unlike Ulvibacter strains, strain KK4T could assimilate glucose, mannose, galactose and acetate. The major quinone and fatty acids were menaquinone-6 and iso-C15 : 0 (27.5 %), iso-C15 : 1 G (22.5 %) and iso-C17 : 0 3-OH (12.8 %), respectively. Based on genetic, phylogenetic and phenotypic properties, strain KK4T represents a novel species of the genus Patiriisocius, for which the name Patiriisocius marinistellae gen. nov., sp. nov. is proposed. The type strain is KK4T (=JCM 33344T=KCTC 72225T). In addition, based on the current data, Ulvibacter marinus should be reclassified as Patiriisocius marinus comb. nov.