Identification and characterization of lactocyclicin Q, a novel cyclic bacteriocin produced by Lactococcus sp. strain QU 12

Appl Environ Microbiol. 2009 Mar;75(6):1552-8. doi: 10.1128/AEM.02299-08. Epub 2009 Jan 9.


Lactococcus sp. strain QU 12, which was isolated from cheese, produced a novel cyclic bacteriocin termed lactocyclicin Q. By using cation-exchange chromatography, hydrophobic interaction chromatography, and reverse-phase high-performance liquid chromatography, lactocyclicin Q was purified from culture supernatant, and its molecular mass was determined to be 6,062.8 Da by mass spectrometry. Lactocyclicin Q has been characterized by its unique antimicrobial spectrum, high level of protease resistance, and heat stability compared to other reported bacteriocins of lactic acid bacteria. The amino acid sequence of lactocyclicin Q was determined chemically, and this compound is composed of 61 amino acid residues that have a cyclic structure with linkage between the N and C termini by a peptide bond. It showed no homology to any other antimicrobial peptide, including cyclic bacteriocins. On the basis of the amino acid sequences obtained, the sequence of the gene encoding the prepeptide lactocyclicin Q was obtained. This is the first report of a cyclic bacteriocin purified from a strain belonging to the genus Lactococcus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacteria / drug effects*
  • Bacteriocins / chemistry
  • Bacteriocins / genetics
  • Bacteriocins / isolation & purification*
  • Bacteriocins / pharmacology*
  • Base Sequence
  • Chromatography, Ion Exchange
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • Hot Temperature
  • Lactococcus / metabolism*
  • Mass Spectrometry
  • Molecular Sequence Data
  • Molecular Weight
  • Peptide Hydrolases / metabolism
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid


  • Bacteriocins
  • DNA, Bacterial
  • Peptide Hydrolases

Associated data

  • GENBANK/AB462499