Muricauda hadalis sp. nov., a novel piezophile isolated from hadopelagic water of the Mariana Trench and reclassification of Muricauda antarctica as a later heterotypic synonym of Muricauda teanensis

A novel marine Gram-stain-negative, non-motile, aerobic and rod-shaped bacterium, designated as strain MT-229 T , was isolated from the deep seawater in the Mariana Trench and characterized phylogenetically and phenotypically. Bacterial optimal growth occurred at 30 °C (ranging 10–40 °C), pH 6 (ranging 3–11) and with 11 % (w/v) NaCl (ranging 0–17 %). Strain MT-229 T was a piezophile, growing optimally at 20 MPa (range 0.1–70 MPa). The nearest phylogenetic neighbours were Muricauda antarctica CGMCC 1.2174 T and Muricauda taeanensis JCM 17757 T with 16S rRNA gene similarity of 98.7 %. The sole respiratory quinone was menaquinone-6 (MK-6). The major polar lipids were phosphatidylethanolamine (PE), two unidentified aminolipids (AL) and ten unidentified lipids. The major fatty acids of strain MT-229 T were iso-C 15 : 0 , iso-C 17 : 0 3-OH and iso-C 15 : 1 G. The G+C content of the genomic DNA was 45.6 mol%. The combined genotypic and phenotypic data indicated that strain MT-229 T represents a novel species of the genus Muricauda , for which the name Muricauda hadalis sp. nov. is proposed, with the type strain MT-229 T (=DSM 109894 T =MCCC 1K04201 T ). In addition, the whole-genome-based comparisons revealed that the type strains of Muricauda antarctica and Muricauda teanensis belong to a single species. It is, therefore, proposed that M. antarctica be recognized as a heterotypic synonym of M. teanensis .