Purification, characterization and structural identification of a novel bacteriocin produced by marine original Enterococcus durans YQ-6, and its inhibition of Listeria monocytogenes

The bacteriocin CAMT6 is a novel bacteriocin produced by Enterococcus durans YQ-6 isolated from Larimichthys polyactis in the South China Sea. In this study, the bacteriocin CAMT6 was purified by extraction using ethyl acetate, Sephadex LH-20 column chromatography, cation exchange chromatography and reversed-phase high-performance liquid chromatography, in sequence. The Liquid Chromatograph Triple Quadrupole Mass Spectrometer (LC-MS/MS) analysis revealed that the relative molecular mass and amino acid sequence of the bacteriocin CAMT6 were 1254.63 Da and N-GAVHDVKDVLDS, respectively. Combined with the circular dichroism (CD) spectroscopy results, CAMT6 was determined to be a novel Class IId bacteriocin. CAMT6 exhibited broad-spectrum antibacterial activity, inhibiting both gram-negative and gram-positive bacteria, even fungi. CAMT6 exhibited strong temperature stability, was stable over pH 2–7, and was inactivated by proteases. CAMT6 also significantly removed L. monocytogenes biofilms and inhibited L. monocytogenes by disrupting the permeability of the cell membrane. Furthermore, CAMT6 can effectively inhibit the growth of L. monocytogenes in chicken breast. These results suggest that the bacteriocin CAMT6 could serve as a potential biological preservative for food.