Ginsenosides are the major pharmacological components in ginseng. We isolated lactic acid bacteria from Kimchi to identify microbial modifications of ginsenosides. Phylogenetic analysis of 16S rRNA gene sequences indicated that the strain DCY65-1 belongs to the genus Lactobacillus and is most closely related to Lactobacillus brevis. On the basis of TLC and HPLC analysis, we found two metabolic pathways: F1 → 6α,12β-dihydroxydammar-3-one-20(S)-O-β-D-glucopyranoside and C-K → 12β-hydroxydammar-3-one-20(S)-O-β-D-glucopyranoside. These results suggest that strain DCY65-1 is capable of potent ketonic decarboxylation, ketonizing the hydroxyl group at C-3. The F1 metabolite had a more potent inhibitory effect on mushroom tyrosinase than did the substrate. Therefore, the F1 and C-K derivatives may be more pharmacologically active compounds, which should be further characterized.