NISIN Z PRODUCED BY Lactococcus lactis FROM BULLFROG HATCHERY IS ACTIVE AGAINST Citrobacter freundii, A RED-LEG SYNDROME RELATED PATHOGEN.

QUINTANA, G.S.; NIEDERLE, M.V.; MINAHK, C.J.; PICARIELLO, G; NADER-MACÍAS, M.E.F; PASTERIS, S.E.

WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY

SPRINGER

Lugar: Berlin; Año: 2017 vol. 33

0959-3993

Lactococcus lactis subsp. lactis CRL 1584 isolated from a bullfrog hatchery produces a bacteriocin that inhibits indigenous Citrobacter freundii (a Red-Leg Syndrome pathogen) and Lactobacillus plantarum, and Listeria monocytogenes. Considering that probiotics requires high cell densities and/or bacteriocin concentrations, the effect of the temperature on L. lactis growth and bacteriocin production was evaluated to find the optimal conditions. Thus, the growth rate was maximal at 36 °C, whereas the highest biomass and bacteriocin activity were achieved between 20-30 °C and 20-25 °C, respectively. The bacteriocin synthesis was closely growth associated reaching the highest values at the end of the exponential phase. Since bacteriocins co-production has been evidenced in bacterial genera, a purification of the bacteriocin/s from L. lactis culture supernatants was carried out. Thus, precipitation with 40% ammonium sulfate allowed getting high bacteriocin activity. Once dissolved in acetate buffer, pH: 5.5, an active fraction was purified by cationic-exchange chromatography. Then, a RP-HPLC was carried out by obtaining a single fraction with antagonistic activity. The purified sample was a peptide with a 3,353.05 Da, a molecular mass that matches nisin Z, which turned out to be the only bacteriocin produced by L. lactis CRL 1584. Nisin Z showed bactericidal effect on C. freundii and L. monocytogenes, which increased in the presence L-lactic acid+H2O2.This is the first report on nisin Z production by L. lactis from a bullfrog hatchery that resulted active on a Gram-negative pathogen. This peptide has potential probiotic for raniculture and as food biopreservative for bullfrog meat.