0023-6152

AA00697606

23943

査読無

0023-6152

AA00697606

A mesophilic r,-lactate producing coccus, Lactococcus lactis IO-1 previously labeled Stretococcus sp. IO-l, was isolated and taxonomical study was carried out. This strain grew under anaerobic conditions, however, it was also capable of growing under microaerophilic conditions. In TGC medium, the strain grew with peculiar filamentous shooting from the top the yellow zone (anaerobic zone) to the bottom in the standing test tube and in double layer plate culture, the convex lens shape colony with dark green color was developed after a few weeks culture. Electron micrograph showed that this microbe was ovoid with the size of 0.8-0.9 pm width X 1.1-1.2 pm length. The strain fermented various carbohydrate to produce L-lactate with high conversion rate and no other volatile fatty acid was detected. The optimal temperture for growth as well as fermentation was 37℃ and the strain tolerant in 6.5 % NaCl. It grew in bile esculin but it did not possessed Lancefield’s D antigen. It possessed Lancefield’s N antigen and puoduced nisin like peptide antibiotics which was sensitive to genus Lactococcus. The mol% G+C of the DNA was 38%. Glutamic acid was one of the essential amino acid for its growth. DNA-DNA hybridization between this strain and Lactococcus lactis NCFB 604T showed very high homology value as 62-77 %. Thus, this strain was indentified as the variant strain of Lactococcus lactis. This strain has been deposited to the Japan Collection of Microorganisms as Lactococcus lactis IO-1 JCM 7638.