A bacteriocin (Reutericin 6) produced by Lactobacillus reuteri LA6, was purified by hydrophobic chromatography from the modified MRS broth (D -MRS) with 6180-fold increase in specific activity with 14% recovery. The molecular weight of reutericin 6 was determined to be 2.7 kDa by SDS-PAGE and ESI-MS. By amino acid analysis, reutericin 6 comprised of 67% hydrophobic and polar neutral amino acids. Lanthionine was not detected. The lytic activity against Lactobacillus delbrueckii subsp. bulgaricus JCM 1002 T and NIAI B6 was detected by the decrease of both turbidity and the number of viable cells, and by leaking of β-galactosidase.