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 omega 7c) and/or C-16:1 omega 6c), iso-C-17:0 30H and summed feature 9 (iso-C-17:1 omega 9c) 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 165 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 526851, 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.