Janibacter zhaoxuefangae sp. nov. and Janibacter zhangyanbonis sp. nov., two novel Actinobacteria isolated from in situ coal

Four novel bacterial strains, designated as G56T, G1551, G349T and G368, were isolated from in situ coal samples. All four strains were Gram-stain-positive, catalase-positive, oxidase-negative, non-motile and aerobic. Phylogenetic analysis based on 16S rRNA gene sequences revealed that G56T and G1551 represented the same species, and that G349T and G368 represented another species, with both species falling within the genus Janibacter. Strains G56T and G1551 exhibited the highest 16S rRNA gene sequence similarity to Janibacter anophelis CCUG 49715T (98.61%), whereas strains G349T and G368 exhibited the highest 16S rRNA gene sequence similarity to Janibacter limosus DSM 11140T and Janibacter terrae NBRC 107853T (99.03-99.10%). The average nucleotide identity and digital DNA-DNA hybridization values between the proposed type strains (G56T and G349T) and species of the genus Janibacter were 74.59-89.54% and 19.70-38.30%, respectively. The DNA G+C contents of G56T and G349T were 71.0 and 71.5 mol%, respectively, and both strains contained only menaquinone MK-8(H₄) as the respiratory quinone. The major cellular fatty acids of strain G56T were C16:0 10-methyl and/or iso-C17:1 ω9c, iso-C17:0 and iso-C15:0, whereas those of strain G349T were C18:1 ω9c, iso-C16:0 and C17:1 ω8c. The polar lipid profiles of both strains comprised diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol, and meso-diaminopimelic acid was identified as the diagnostic diamino acid in the cell wall. Based on phenotypic, phylogenetic and chemotaxonomic evidence, strains G56T and G349T were considered to represent two novel species of the genus Janibacter, for which the names Janibacter zhaoxuefangae sp. nov. and Janibacter zhangyanbonis sp. nov. are proposed. The type strains are G56T (=GDMCC 1.5581T=JCM 37886T) and G349T (=GDMCC 1.5549T=JCM 37887T).