Detection and characterization of bacteriocin-producing Lactococcus lactis strains

Abstract

One hundred sixty seven strains of Lactococcus lactis were screened for bacteriocin production by well diffusion assay of GM17 agar. Fourteen (8.4%) produced antimicrobial activity other than organic acids, bacteriophages or hydrogen peroxide. The frequency of bacteriocin production ranged from 2% in L. lactis subsp. cremoris up to 12% in L. lactis subsp. lactis. Antimicrobial activities were not observed in any strain of L. lactis subsp. lactis var. diacetylactis. Among thirteen bacteriocin-producing strains and two nisin-producing strains (L. lactis subsp. lactis ATCC 11454 and L. lactis subsp. lactis CNRZ 150), eight (53%) were characterized as lactose-positive (Lac + ) and proteinase-negative (Prt -). The bacteriocin-producing cultures were also characterized on the basis of plasmid content. All strains had 2 to 7 plasmids with molecular weights varying from 0.5 to 28.1 Mdal. Four strains (ITAL 435, ITAL 436, ITAL 437 and ITAL 438) showed identical profiles and the other were quite distinct.

Protocols for the isolation and detection of lactic acid bacteria with bacteriocinogenic potential

“…In addition to minimizing the production of acids, the BHI used in this study received a solution of catalase to hydrolyze the hydrogen peroxide that may have been produced by the tested LAB cultures (Moreno, Lerayer, & Leitão, 1999;Schillinger & Lücke, 1989). Hydrogen peroxide is another substance with antimicrobial potential produced by LAB (Carr et al, 2002) and may interfere with the identification of antimicrobial activity from the production of bacteriocins or bacteriocin-like substances.…”

Antilisterial activity of lactic acid bacteria isolated from vacuum-packaged brazilian meat and meat products

“…Moreno et al (18) reported that 8.4% of 167 strains of a culture collection were able to inhibit all the indicator microorganisms studied and Hastings et al (9) isolated five bacteriocin-producing lactic acid bacteria from 139 cultures.…”

Bacteriocins from lactic acid bacteria: purification, properties and use as biopreservatives

“…Moreno et al (1999) have isolated several strains of lactic acid bacteria from food products as cheese and milk. The antagonistic activity was detected through the well diffusion assay on agar plates (Toro, 2005).…”