Biochemical identification of bacteriocins from Enterococcus faecalis 710C
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Abstract
Enterococcus faecalis 710C is a lactic acid bacterium that produces two bacterocins, ent7A and ent7B. Both ent7A and ent7B have strong activity against gram-positive food pathogens including Listeria spp., Clostridium spp., vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA). Mass spectrometry analyses revealed that both ent7A (5201 Da) and ent7B (5207 Da) have formylated N-terminal methionine. The amino acid sequences, structural gene sequences of ent7 from nucleotide position 1-275 and immunity gene were determined. Circular dichroism data suggest that in aqueous solution ent7A and ent7B have 20 to 25% alpha-helical region. Addition of membrane-mimicking reagent (trifluoroethanol) did not significantly enhance the alpha-helical content in ent7A and ent7B. Chiral analysis by gas chromatography- mass spectrometry showed that the amino acid residues elucidated in ent7A and ent7B were all in L-configuration.