Sphingobacterium cavernae sp. nov., a novel bacterium isolated from soil sampled at Tiandong Cave

A Gram-stain-negative, non-motile and rod-shaped bacterium, designated strain 5.0403-2^T, was isolated from a cave soil sample collected from Tiandong Cave, Guizhou Province, south-west PR China. Cells showed positive oxidase and catalase reactions. The predominant isoprenoid quinone was MK-7. The major fatty acids were identified as iso-C_15 : 0, summed feature 3 (C_16 : 1 ω7c and/or C_16 : 1 ω6c), iso-C_17 : 0 3OH and summed feature 9 (iso-C_17 : 1 ω9c or C_16 : 0 10-methyl). The cellular polar lipids contained phosphatidylethanolamine, one unidentified phospholipid, three unidentified phosphoglycolipids and four unidentified lipids. The genomic DNA G+C content was 36.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 5.0403-2^T should be assigned to the genus Sphingobacterium. Results of 16S rRNA gene sequence similarity analysis showed that strain 5.0403-2^T was most similar to Sphingobacterium bovisgrunnientis KCTC 52685^T (98.7 %), Sphingobacterium composti KCTC 12578^T (98.0 %) and Sphingobacterium alimentarium DSM 22362^T (97.3 %) and less than 95.0 % similar to other species of the genus Sphingobacterium. The average nucleotide identity values between strain 5.0403-2^T and S. bovisgrunnientis KCTC 52685^T, S. composti KCTC 12578^T and S. alimentarium DSM 22362^T were 94.2, 82.3 and 77.2 % respectively. The digitalDNA-DNA hybridization values between strain 5.0403-2^T and S. bovisgrunnientis KCTC 52685^T, S. composti KCTC 12578^T and S. alimentarium DSM 22362^T were 68.4, 25.6 and 20.7 %. These results indicated that the isolate represented a novel genomic species. The polyphasic taxonomic characteristics indicated that strain 5.0304-2^T represents a novel species of the genus Sphingobacterium, for which the name Sphingobacterium cavernae sp. nov. (type strain 5.0403-2^T=KCTC 62981^T=CCTCC AB 2019257^T) is proposed.