Proposal of Parashewanella gen. nov. to accommodate Parashewanella curva sp. nov. and Parashewanella spongiae comb. nov. in the Shewanellaceae.

Abstract

A Gram-stain-negative, non-spore-forming, motile, aerobic, curved rod shaped bacterium, designed strain C51T, was isolated from coral (genus Porites) sampled at Weizhou Island, China. The optimal growth occurred in 2-3 % NaCl (w/v), at 25 °C and pH 8. Phylogenetic analyses based on the 16S rRNA gene, the gyrB gene and the Up-to-date Bacterial Core Gene set (92 genes) indicated that strain C51T forms a stable cluster with Shewanella spongiae KCTC 22492T, and had 94 % 16S rRNA gene similarity to its closest type strain S. spongiae KCTC 22492T. The only detected respiratory quinone was Q-8 and it could not produce menaquinone. The genome DNA G+C content was 40.1 mol%. The major cellular fatty acids were iso-C11:0 3-OH, iso-C15:0, C16:0, C16:1ω7c/ω6c, C18:0 and iso-C13:0 3-OH. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, three unidentified aminolipids and three unidentified polar lipids. Its low genome DNA G+C content, lack of an aminolipid and a difference in its substrate oxidation ability indicated that strain C51T should represent a new species. Furthermore, its distinct phylogeny, Shewanella-specific FISH probe SHEW227 mismatch, lower cellular G+C content and inability to produce menaquinones indicated that the C51T clade should represent a new genus in the Shewanellaceae, for which the name Parashewanella gen. nov. is proposed, the type species is Parashewanella spongiae comb. nov., and another species is Parashewanella curva sp. nov. The type strains of Parashewanella spongiae and Parashewanella curva are HJ039T (=KCTC 22492T=KCCM 42304T=JCM 13830T) and C51T (=MCCC 1K03463T=KCTC 62318T), respectively.