Note: Genetic and biochemical characterization of nisin Z produced by Lactococcus lactis ssp. lactis biovar diacetylactis UL 719

The bacteriocin produced by Lactococcus lactis ssp. lactis biovar. dialetylactis UL 719 was purified and characterized. Two peaks exhibiting antimicrobial activity were obtained after purification. Primary structure of the peptide of major peak 2 was identical to that of nisin Z when determined by Edman degradation and confirmed by DNA sequence analysis. The molecular mass as determined by mass spectrometry was 3346.39 +/- 0.40 Da for peak 1 and 3330.39 +/- 0.27 Da for peak 2, which suggeststhat peak 1 may correspond to an oxidized form of nisin Z. The two purified peaks exhibiting antimicrobial activity appear to correspond with the oxidized and native forms of nisin Z.