Characterization of bacteriocins produced by "Lactococcus lactis" strains

Moreno, IzildinaLerayer, Alda L. SBaldini, Vera L. SLeitão, Mauro F. de F

Bacteriocins produced by fifteen strains of "Lactococcus lactis" (14 "L. lactis" subsp. "lactis" and one "L. lactis" subsp. "cremoris") were heat resistant, sensitive to several proteolytic enzymes and active over a wide range of pH. Their resistance to the heating was greatly influenced by pH. Only the strain "L. lactis" subsp. "lactis" ITAL 383 produced a bacteriocin with a wide activity spectrum, similar to nisin of "L. lactis" ATCC 11454. This bacteriocin inhibited closely related species and other Gram-positive microorganisms including "Listeria monocytogenes" and "Staphylococcus", but it was not active against the Gram-negative bacteria tested. The identification of partially purified antimicrobial compounds by SDS-PAGE showed that bacteriocin produced by strain ITAL 383 had the same molecular weight of nisin produced by "L. lactis" subsp. "lactis" ATCC 11454.