A Gram-negative, strictly aerobic, non-motile, non-sporeforming, and rod-shaped bacterial strain designated FW-6T was isolated from a freshwater sample and its taxonomic position was investigated by using a polyphasic approach. Strain FW-6T grew optimally at 10-42 degrees C and at pH 7.0 on nutrient and R2A agar. Strain FW-6T displayed beta- glucosidase activity that was responsible for its ability to transform ginsenoside Rb1 (one of the dominant active components of ginseng) to Rd. On the basis of 16S rRNA gene sequence similarity, strain FW-6T was shown to belong to the family Sphingomonadaceae and was related to Novosphingobium aromaticivorans DSM 12444T (98.1% sequence similarity) and N. subterraneum IFO 16086T (98.0%). The G+C content of the genomic DNA was 64.4%. The major menaquinone was Q-10 and the major fatty acids were summed feature 7 (comprising C18:1 omega9c/ omega12t/omega7c), summed feature 4 (comprising C16:1 omega7c/iso- C15:0 2OH), C16:0, and C14:0 2OH. DNA and chemotaxonomic data supported the affiliation of strain FW-6T to the genus Novosphingobium. Strain FW-6T could be differentiated genotypically and phenotypically from the recognized species of the genus Novosphingobium. The isolate that has ginsenoside converting ability therefore represents a novel species, for which the name Novosphingobium ginsenosidimutans sp. nov. is proposed, with the type strain FW-6T (= KACC 16615T = JCM 18202T).