Armatimonas rosea gen. nov., sp. nov., of a novel bacterial phylum, Armatimonadetes phyl. nov., formally called the candidate phylum OP10

<jats:p>A novel aerobic, chemoheterotrophic bacterium, strain YO-36<jats:sup>T</jats:sup>, isolated from the rhizoplane of an aquatic plant (a reed, <jats:italic>Phragmites australis</jats:italic>) inhabiting a freshwater lake in Japan, was morphologically, physiologically and phylogenetically characterized. Strain YO-36<jats:sup>T</jats:sup> was Gram-negative and ovoid to rod-shaped, and formed pinkish hard colonies on agar plates. Strain YO-36<jats:sup>T</jats:sup> grew at 20–40 °C with optimum growth at 30–35 °C, whilst no growth was observed at 15 °C or 45 °C. The pH range for growth was 5.5–8.5 with an optimum at pH 6.5. Strain YO-36<jats:sup>T</jats:sup> utilized a limited range of substrates, such as sucrose, gentiobiose, pectin, gellan gum and xanthan gum. The strain contained C<jats:sub>16 : 0</jats:sub>, C<jats:sub>16 : 1</jats:sub>, C<jats:sub>14 : 0</jats:sub> and C<jats:sub>15 : 0</jats:sub> as the major cellular fatty acids and menaquinone-12 as the respiratory quinone. The G+C content of the genomic DNA was 62.4 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain YO-36<jats:sup>T</jats:sup> belonged to the candidate phylum OP10 comprised solely of environmental 16S rRNA gene clone sequences except for two strains, P488 and T49 isolated from geothermal soil in New Zealand; strain YO-36<jats:sup>T</jats:sup> showed less than 80 % sequence similarity to strains P488 and T47. Based on the phylogetic and phenotypic findings, a new genus and species, <jats:italic>Armatimonas rosea</jats:italic> gen. nov., sp. nov., is proposed for the isolate (type strain YO-36<jats:sup>T</jats:sup>  = NBRC 105658<jats:sup>T</jats:sup>  = DSM 23562<jats:sup>T</jats:sup>). In addition, a new bacterial phylum named <jats:italic>Armatimonadetes</jats:italic> phyl. nov. is proposed for the candidate phylum OP10 represented by <jats:italic>A. rosea</jats:italic> gen. nov., sp. nov. and <jats:italic>Armatimonadaceae</jats:italic> fam. nov., <jats:italic>Armatimonadales</jats:italic> ord. nov., and <jats:italic>Armatimonadia</jats:italic> classis nov.</jats:p>