Two new members of the genus Sphingobacterium: Sphingobacterium zhuxiongii sp. nov. and Sphingobacterium luzhongxinii sp. nov.

Four strains, designated dk4302 T , dk4209, xlx-73 T , and xlx-183, were isolated from Tibetan gazelle and red swamp crawfish collected from the Qinghai–Tibet Plateau and Jiangxi Province, PR China. The strains were Gram-stain-negative, aerobic, rod-shaped, non-motile, mucoid, and yellow-pigmented. Strains dk4302 T and dk4209 grew at 10–40 °C and pH 6.0–9.0, while strains xlx-73 T /xlx-183 grew at 15–40 °C and pH 6.0–10.0. Both strains exhibited growth in the presence of up to 3.5 % (w/v) NaCl. Phylogenetic and phylogenomic analyses based on the 16S rRNA gene sequences and 652 core genes, respectively, revealed that the four strains formed two distinct clusters in the genus Sphingobacterium . Strains dk4302 T and dk4209 formed a distinct clade with Sphingobacterium hotanense XH4 T and Sphingobacterium humi D1 T . The most closely related strains to xlx-73 T and xlx-183 were Sphingobacterium nematocida M-SX103 T . The DNA G+C contents were 38.9 and 39.8 mol%. The digital DNA–DNA hybridization (dDDH) values between dk4302 T and S. humi D1 T and S. hotanense XH4 T were 19.2 and 21.8 % (19.0 and 21.6 % for strain dk4209), respectively. The corresponding average nucleotide identity (ANI) values were 74.3 and 78.1 % (74.4 and 78.3 % for strain dk4209), respectively. The dDDH values between xlx-73 T (xlx-183) and S. nematocida M-SX103 T was 24.6 % (25.7 %). The corresponding ANI value was 85.7 % (85.5 % for strain xlx-183). The major fatty acid and respiratory quinone of dk4302 T and xlx-73 T were iso-C 15:0 and MK7. The polar lipids identified in all of the novel strains were phosphatidylethanolamine, phosphoglycolipids, aminophospholipids, and phospholipids. A total of 61/190 (32.1 %) and 82/190 (43.2 %) carbon substrates were metabolized by strains dk4302 T and xlx-73 T in the Biolog MicroPlates, respectively. Based on the results from this polyphasic taxonomic study, two novel species in the genus Sphingobacteruim are proposed, namely Sphingobacteruim zhuxiongii sp. nov. (type strain dk4302 T =CGMCC 1.16795 T =JCM 33600 T ) and Sphingobacteruimluzhongxinii sp. nov. (type strain xlx-73 T =GDMCC 1.1712 T =JCM 33886 T ).