Nisin-producing Lactococcus spp. from mayonnaise-based products and their raw materials

Three bacteriocins were purified from lactic acid bacteria isolated from mayonnaise-based finished products and the raw materials used in the production of the finished products. All three bacteriocin-producing strains (EN3a, EN14a, and EN15b) were identified by sequencing of the 16S rDNA as Lactococcus lactis. The RP-HPLC fractions showed strong antimicrobial activity against Listeria monocytogenes. Mass spectrometry analysis of active fractions showed that all strains produced nisin A (3,353.7 Da). These results were confirmed by amplification of nisin structural gene by PCR, by lack of activity against a nisin-producing strain, and by total loss of activity after reaction of purified bacteriocins with glutathione. The strains Lactococcus lactis EN3a, EN14a, and EN15b are the first nisin-producing strains isolated from mayonnaise-based commercial products and from the raw materials used in their production. The ability of these strains to produce nisin could be useful to improve food quality of these and related products.