Identification of bacteriocinogenic strains isolated of raw milk and soft chesse in Viçosa, Minas Gerais, Brasil

KATIA GIANNI DE CARVALHO; MARIA BEATRIZ ORTOLANI; GABRIELA VIÇOSA; PAULA MORAES; FERNANDO SESMA; BERNADETTE DORA GOMBOSSY DE MELO FRANCO; LUIS AUGUSTO NERO

San Miguem de Tucuman

Simposio; III Simposio Internacional de Bacterias Lacticas; 2009

Lactic acid bacteria (LAB) are being used by food industries due to their ability in producing metabolites, like bacteriocins, with antimicrobial activity against Gram positive pathogens and spoilage microorganisms. The objectives of this study were identify naturally occurring bacteriocinogenic LAB in raw milk and soft cheese, verifying their sensitivity to proteolytic enzymes, and detect the presence of nisin genes in cultures identified as Lactococcus lactis. 389 LAB cultures were isolated from raw milk and soft cheese samples, and submitted to the detection of bacteriocins production against Listeria monocytogenes. From 58 (14.9%) LAB cultures identified as antagonistic, 20 were randomly selected and submitted to enzymatic tests in order to confirm the proteinaceous nature of antimicrobial substances. Still, these cultures were submitted to 16S rDNA sequencing, and were identified as Lactobacillus plantarum (2) and Lc. lactis subsp. lactis (18). Nisin genes were identified by polymerase chain reaction in 7 of these cultures. The identified bacteriocinogenic cultures presented high variability in production and activity of the bacteriocins, even when they shared high genetic similarity.