Leucobacter shiyiweii sp. nov. and Leucobacter fengyongliangi sp. nov., isolated from coal samples in Shanxi Province of China

Four novel bacterial strains representing two novel species were isolated from in situ coal samples. Comparative analysis of 16S rRNA gene sequences showed that strains W1153 T and W1478 share the highest sequence similarity with Leucobacter tardus K 70/01 T (98.3%), whereas strains Z1108 T and W1038 share the highest sequence similarity with L. tardus K 70/01 T and Leucobacter exalbidus K-540B T (98.0%). Phylogenetic analysis based on 16S rRNA gene sequences and a core-genome phylogeny constructed from 665 core genes demonstrated that the four strains form two distinct clades, clearly separated from other species within the genus Leucobacter . Whole-genome sequencing revealed genome sizes ranging from 2.6 to 2.8 Mb, with G+C contents of 62.5–63.5 mol%. The average nucleotide identity and digital DNA–DNA hybridization values between the four strains and all recognized species within the genus Leucobacter ranged from 71.1 to 75.6% and 19.3 to 25.6%, respectively. The major cellular fatty acids of the four strains were anteiso-C 15 : 0 , anteiso-C 17 : 0 and iso-C 16 : 0 . The respiratory quinone types were MK-11 for strain W1153 T and MK-9(H8) for strain Z1108 T . The main cell-wall sugars were rhamnose and ribose, with 2,4-diaminobutyric acid present as the diagnostic diamino acid. Based on phenotypic characteristics, phylogenetic analyses and chemotaxonomic evidence, strains W1153 T and W1478, and Z1108 T and W1038, are proposed as representing two novel species within the genus Leucobacter , named Leucobacter shiyiweii sp. nov. and Leucobacter fengyongliangi sp. nov., respectively. The type strains are W1153 T (=GDMCC 1.5845 T =KCTC 59606 T ) and Z1108 T (=GDMCC 1.5846 T =KCTC 59607 T ).