Enterococcus faecium P21: a strain occurring naturally in dry-fermented sausages producing the class II bacteriocins enterocin A and enterocin B

Enterococcus faecium P21 isolated from a Spanish dry-fermented sausage show s a narrow antimicrobial activity against closely related lactic acid bacte ria and strong antimicrobial activity against spoilage and foodborne Gram-p ositive pathogenic bacteria such as Listeria monocytogenes, Staphylococcus aureus, Clostridium perfringens and Clostridium botulinum. The antimicrobia l activity is produced during growth in MRS broth at 32 degreesC; it is hea t resistant (20 min at 80-100 degreesC) and abolished by protease treatment , and withstands exposure to pH 2-11 freeze-thawing, lyophilization and lon g term storage at -20 degreesC. Purification of the antimicrobial activity by ammonium sulphate precipitation, gel filtration and cation-exchange, hyd rophobic interaction and reverse-phase chromatographies showed that the bro ad antimicrobial spectrum exerted by E. faecium P21 was indeed due to two p eptide bacteriocins. Studies on their N-terminal amino acid sequences and P CR and DNA analyses revealed that these bacteriocins are identical to the c lass ii bacteriocins enterocin A and enterocin B. The genetic organization of the enterocin A (EntA) operon in E. faecium P21 shows that the bacterioc in structural gene (entA) the immunity gene (entiA) and the induction pepti de gene (entF) are clustered and colinearly arranged. Strikingly, this orga nization was structurally different to that reported for the EntA-producer E. faecium CTC492. (C) 2001 Academic Press.