Identification and characterization of novel multiple bacteriocins produced by Leuconostoc pseudomesenteroides QU 15

Aim: To characterize novel multiple bacteriocins produced by Leuconostoc pseudomesenteroides QU 15. Methods and Results: Leuconostoc pseudomesenteroides QU 15 isolated from Nukadoko (rice bran bed) produced novel bacteriocins. By using three purification steps, four antimicrobial peptides termed leucocin A (ΔC7), leucocin A‐QU 15, leucocin Q and leucocin N were purified from the culture supernatant. The amino acid sequences of leucocin A (ΔC7) and leucocin A‐QU 15 were identical to that of leucocin A‐UAL 187 belonging to class IIa bacteriocins, but leucocin A (ΔC7) was deficient in seven C‐terminal residues. Leucocin Q and leucocin N are novel class IId bacteriocins. Moreover, the DNA sequences encoding three bacteriocins, leucocin A‐QU 15, leucocin Q and leucocin N were obtained. Conclusions: These bacteriocins including two novel bacteriocins were identified from Leuc. pseudomesenteroides QU 15. They showed similar antimicrobial spectra, but their intensities differed. The C‐terminal region of leucocin A‐QU 15 was important for its antimicrobial activity. Leucocins Q and N were encoded by adjacent open reading frames (ORFs) in the same operon, but leucocin A‐QU 15 was not. Significance and Impact of Study: These leucocins were produced concomitantly by the same strain. Although the two novel bacteriocins were encoded by adjacent ORFs, a characteristic of class IIb bacteriocins, they did not show synergistic activity.