Various strains of Lactobacillus and Leuconostoc species were evaluated to select the most promising strain to carry out transforming major ginsenosides into minor ginsenosides. Among the experimental lactic acid bacteria (LAB), Leuconostoc mesenteroides KFRI 690, Leuconostoc paramesenteroides KFRI 159, and Lactobacillus delbrueckii KCCM 35486 produced compound K from major ginsenosides precursors (Rb1, Rc, Rd, and F2). KFRI 690 showed the best transforming activity among them. Furthermore, these LABs could biotransform ginsenosides without disrupting the cell to release enzyme activity. The conversion ratio of Rb1 to compound K using KFRI 690 has been enhanced up to 97.8% by adding 2% sucrose into the culture medium. This is the first report on the production of compound K using whole cells of Leu. mesenteroides, Leu. paramesenteroides, and Lb. delbrueckii, which are food grade lactic acid bacteria.