Lactococcus

Lac.to.coc'cus. L. n.lacmilk, L. gen. n.lactisof milk, Gr. n.coccus(kokkos) a grain or berry; N.L. masc. n.Lactococcusmilk coccusFirmicutes / “Bacilli” / “Lactobacillales” / Streptococcaceae / LactococcusSpheres or ovoid cells occur singly, in pairs, or in chains, and are often elongated in the direction of the chain. Gram‐stain‐positive. Endospores are not formed. Nonmotile. Not β‐hemolytic. Facultatively anaerobic; catalase‐negative. Growth at 10°C but not at 45°C. Usually grows in 4% (w/v) NaCl with the exception ofLactococcus lactissubsp.cremoriswhich only tolerates 2% (w/v) NaCl. Chemo‐organotroph. Metabolism fermentative. The predominant end product of glucose fermentation isL(+)‐lactic acid. May contain menaquinones. Most strains react with group N antisera (Lancefield, 1 9 3 3). Nutritional requirements are complex and variable. The peptidoglycan is of group A withL‐lysine as diamino acid in position 3 of the peptide subunit. Typical inhabitants of plants, animals, and their products.DNA G+C content(mol%): 34–43 (Tm).Type species:Lactococcus lactis(Lister 1 8 7 3) Schleifer, Kraus, Dvorak, Kilpper‐Bälz, Collins and Fischer 1 9 8 6, 354VP(Effective publication:Lactococcus lactisSchleifer, Kraus, Dvorak, Kilpper‐Bälz, Collins and Fischer 1 9 8 5, 189.) (Bacterium lactisLister 1 8 7 3, 408;Streptococcus lactisLöhnis 1 9 0 9, 554.)