Sphingobacterium jejuense sp nov., with ginsenoside-converting activity, isolated from compost

A Gram-stain-negative, strictly aerobic, non-motile, light yellow, short-rod bacterium (designated GJ30-7(T)) isolated from compost, was characterized using a polyphasic approach, in order to clarify its taxonomic position. Strain GJ30-7(T) was observed to grow optimally at 30 degrees C and at pH 7.0 on R2A agar medium. Strain Gsoil GJ30-7(T) possessed beta-glucosidase activity, which was responsible for its ability to transform ginsenosides Rb1 and Rc (the two main active components of ginseng) to ginsenoside F2. Phylogenetic analysis, based on 16S rRNA gene sequence similarities, indicated that GJ30-7(T) belongs to the genus Sphingobacterium of the family Sphingobacteriaceae and was most closely related to Sphingobacterium yanglingense JCM 30166(T) (92.6 %), Sphingobacterium psychroaquaticum KACC 18188(T) (92.6 %), and Sphingobacterium thermophilum KCTC 23708(T) (92.0%). The DNA G+C content was 43 mol% and MK-7 was the major isoprenoid quinone. The main polar lipids were phosphatidylethanolamine, one unidentified phospolipid and one unknown polar lipid. In contrast to standard and reference strains, unidentified sphingolipid was also present. The predominant fatty acids of strain GJ30-7(T) were iso-C-15 : 0, iso-C-17 : 0 3-OH, C-16 : 1 omega 7c and/or C-16 : 1 omega 6c (summed feature 3) and iso-C-17 : 1 omega 9c and/or C-16 : 0 10-methyl (summed feature 9), supporting the affiliation of strain GJ30-7(T) to the genus Sphingobacterium. However, strain GJ307(T) could be distinguished genotypically and phenotypically from species of the genus Sphingobacterium with validly published names. The novel isolate therefore represents a novel species, for which the name Sphingobacterium jejuense sp. nov. is proposed, with the type strain GJ30-7(T) (= KACC 18625(T) = JCM 30948(T)).