Maltaricin CPN, a new class IIa bacteriocin produced by Carnobacterium maltaromaticum CPN isolated from mould-ripened cheese.

Abstract

The purpose of this study was to isolate, characterize and determine the structure and the antibacterial activities of a bacteriocin produced by Carnobacterium maltaromaticum CPN, a strain isolated from unpasteurized milk Camembert cheese. This bacteriocin, termed maltaricin CPN, was produced at higher amounts in MRS broth at temperatures between 15°C and 25°C. It was purified to homogeneity from culture supernatant by using a simple method consisting of cation-exchange and reversed-phase chromatographies. Mass spectrometry showed that maltaricin was a 4427·29Da bacteriocin. Its amino acid sequence was determined by Edman degradation which showed that it had close similarity with bacteriocins of the class IIa. Maltaricin CPN consisted in fact of 44 unmodified amino acids including two cysteine residues at positions 9 and 14 linked by a disulphide bond. The antimicrobial activity of maltaricin CPN covered a range of bacteria, with strong activity against many species of Gram-positive bacteria, especially the food-borne pathogen Listeria monocytogenes, but no activity against Gram-negative ones. In the studied conditions, C.maltaromaticum CPN produced a new class IIa bacteriocin with strong anti-Listeria activity. The study covers the purification and the structural characterization of a new bacteriocin produced by strain C.maltaromaticum CPN isolated from Camembert cheese. Its activity against strains of L.monocytogenes and higher production rates at relatively low temperatures show potential technological applications to improve the safety of refrigerated food.