The new lantibiotic nukacin producers, strain ISK-1 previously labeled as Pediococcus sp. ISK-1 and strain Nagano, were characterized biochemically and genetically. Cells were spherical, 0.6 µm in size, and occurred in pairs. The strains were gram-positive, catalase positive and produced more than 75% of DLlactic acid from glucose and their growth was stimulated by mevalonic acid. The strains tolerated 18% NaCl. GϩC content was 36%. 16S rRNA homology revealed that the strains resembled Staphylococcus warneri. Both strains were confirmed by quantitative DNA-DNA hybridization to be variant strains of S. warneri. These strains have been deposited in the Japan Collection of Microorganism as S. warneri JCM 10004 for strain ISK-1 and S. warneri JCM 10005 for strain Nagano.In the northern Kyushu area, many old aged Nukadoko (bed of fermented rice bran) have been maintained until now and some are believed to have lasted for a few hundred years (Kimura et al., 1997). Nukadoko is usually used for pickle fermentation using washed vegetables without any aseptic treatment. We therefore suspected that Nukadoko must possess a native microflora control system that attacks undesirable microorganisms that comes into contact with the bed from the environment. We isolated two organisms, strain ISK-1 and strain Nagano, from an old aged bed owned by Mrs. Sato in Kitakyushu-shi, Japan, a cooking instructor for Iwashino-Nukamisodaki which is a local traditional Japanese cuisine, consisting of cooked sardine with old aged Nukadoko. These strains were isolated by the following procedure. One gram of Nukadoko was suspended in 10 ml of pure water and stood for 24 h at 30°C. One milliliter of the suspension was suspended in 100 ml of thioglycolate (TGC, Difco Laboratories, Detroit, MI, USA) with 1.5% agar and 1.5% CaCO 3 to which NaN 3 10 ppm and cycloheximide 10 ppm were supplemented. The agar plates were incubated in an anaerobic jar for 2 days. The organism was purified by repeating single colony isolation on TGC agar plate.Strain ISK-1 and strain Nagano grew in both anaerobic and microaerophilic conditions. These strains were gram-positive cocci occurring in pairs, catalase positive, and produced more than 75% of DL-lactic acid from glucose with only a little amount of acetic acid. Lactic acid was determined in the form of L-and D-in-