ISOLATION OF NISIN-PRODUCING LACTOCOCCUS-LACTIS STRAINS FROM DRY FERMENTED SAUSAGES

A total Of 4608 lactic acid bacteria (LAB) were isolated from 24 Spani sh fermented sausages and screened for bacteriocin production. Two str ains, BB24 and G18, produced bacteriocins that inhibited a broad spect rum of Gram-positive bacteria. BB24 and G18 were tentatively identifie d as Lactococcus lactis by carbohydrate fermentation patterns and othe r biochemical characteristics. The characterization of their bacterioc ins suggested that both could be the well-known lantibiotic nisin. Thi s was confirmed by PCR analysis of their genomic DNA. Nucleotide seque ncing revealed that they produced nisin A. The fact that BB24 and G18 were isolated from sausages produced in two different regions of Spain suggests that nisin-producing L. lactis strains may be more widesprea d in meat products than previously thought. Nisin produced by L. lacti s BB24 has been purified to homogeneity by a procedure that included a mmonium sulphate precipitation and cation-exchange, hydrophobic-intera ction and reverse-phase chromatography. The purification procedure was simple, rapid and reproducible.