A Novel Bacteriocin With A Ygngv Motif From Vegetable-Associated Enterococcus Mundtii: Full Characterization And Interaction With Target Organisms

A novel broad-spectrum antimicrobial peptide produced by vegetable-associated
Enterococcus mundtii was purified and characterized, and designated mundticin. To
our knowledge, this is the first report on bacteriocin production by this
organism. The elucidation of the full primary amino acid sequence of mundticin
(KYYGNGVSCNKKGCSVDWGKAIGIIGNNSAANLATGGAAGWSK) revealed that this antimicrobial
peptide belongs to the class IIa bacteriocins of lactic acid bacteria which share
a highly conserved N-terminal 'YGNGV' motif. Data obtained by computer modelling
indicated an oblique orientation of the alpha-helical regions of mundticin and
homologous class IIa bacteriocins at a hydrophobic-hydrophilic interface, which
may play a role in the destabilization of phospholipid bilayers. The average mass
of mundticin, as determined by electron spray mass spectrometry, was found to be
4287.21+/-0.59 Da. With respect to its biological activity, mundticin was shown
to inhibit the growth of Listeria monocytogenes, Clostridium botulinum and a
variety of lactic acid bacteria. Moreover, it was demonstrated to have a
bactericidal effect on L. monocytogenes as a result of the dissipation of the
membrane potential, and a loss of intracellular ATP in absence of ATP leakage.
Its good solubility in water, and its stability over a wide pH and temperature
range indicate the potential of this broad spectrum bacteriocin as a natural
preservation agent for foods.