PCR detection of the structural genes of nisin Z and lacticin 481 in Lactococcus lactis subsp. lactis INIA 415, a strain isolated from raw milk Manchego cheese

A Lactococcus strain with strong antimicrobial activity was isolated from raw milk Manchego cheese during a survey on the production of bacteriocins by lactic acid bacteria present in raw milk cheeses. It was identified as Lactococcus lactis subsp. lactis, phenotypically by its morphological and physiological characteristics and genotypically by a PCR technique. When tested for tolerance to known bacteriocins produced by lactococci, it was shown to be resistant to nisin A and nisin Z. The presence of genes encoding nisin and lacticin 481 was revealed by PCR techniques with specific probes. Sequences of the respective PCR amplified fragments matched sequences reported for nisin Z and lacticin 481.