Four Gram-stain-negative, non-spore-forming, motile, short rod-shaped strains (LY29T, LY160, LY54T and LY1275) were isolated from soil of the Qinghai-Tibetan Plateau, China. Based on 16S rRNA gene sequences, strain pairs LY29T/LY160 and LY54T/LY1275 were identified as members of the genera Sphingomonas and Sphingosinicella, respectively, with highest similarities to Sphingomonas alba SE158T (97.8%) and Sphingomonas montis DRJ-4T (98.0%), respectively. In phylogenomic analyses based on 426 core gene sequences, LY29T and LY160 clustered with Sphingomonas rhizophila THG-T61T, while LY54T and LY1275 were closely related to Sphingosinicella humi QZX222T, Sphingosinicella flava UDD2T and Sphingosinicella vermicomposti KCTC 22446T. Digital DNA-DNA hybridization and average nucleotide identity values between the four strains and their closest relatives were determined to be below 24.2% and 80.49%, respectively, thus falling below the recommended species delineation thresholds (70% and 95-96%, respectively). The genomic DNA G+C contents of strains LY29T and LY54T were 64.8 and 66.8 mol%, respectively. Strain LY29T contained predominant fatty acids C16 (C16:1 ω7c and C16:1 ω6c) and C18 (C18:1 ω7c and C18:1 ω6c), while LY54T had iso-C16:0 as the major fatty acid. Both strains shared major polar lipids (diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unidentified sphingoglycolipid). Strain LY29T possessed ubiquinone Q-10 and homospermidine, whereas LY54T contained MK-9(H2) as the major quinone. Based on a polyphasic taxonomic approach, type strains LY29T (=GDMCC 1.4177T=JCM 36472T) and LY54T (=GDMCC 1.4236T=KCTC 8630T) represent novel species of the genera Sphingomonas and Sphingosinicella, for which the names Sphingomonas lindongxini sp. nov. and Sphingosinicella wutangchuni sp. nov. are proposed.
Cao et al. (Wed,) studied this question.