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-ass ociated Enterococcus mundtii was purified and characterized, and desig nated mundticin, To our knowledge, this is the first report on bacteri ocin production by this organism. The elucidation of the full primary amino acid sequence of mundticin (KYYGNGVSCNKKGCSVDWGKAIGIIGNNSAANLATG GAAGWSK) revealed that this antimicrobial peptide belongs to the class IIa bacteriocins of lactic acid bacteria which share a highly conserv ed N-terminal 'YGNGV' motif, Data obtained by computer modelling indic ated an oblique orientation of the alpha-helical regions of mundticin and homologous class IIa bacteriocins at a hydrophobic-hydrophilic int erface, which may play a role in the destabilization of phospholipid b ilayers, The average mass of mundticin, as determined by electron spra y mass spectrometry, was found to be 4287.21+/-0.59 Da. With respect t o its biological activity, mundticin was shown to inhibit the growth o f Listeria monocytogenes, Clostridium botulinum and a variety of lacti c acid bacteria. Moreover, it was demonstrated to have a bactericidal effect on L. monocytogenes as a result of the dissipation of the membr ane potential, and a loss of intracellular ATP in absence of ATP leaka ge. Its good solubility in water, and its stability over a wide pH and temperature range indicate the potential of this broad spectrum bacte riocin as a natural preservation agent for foods. (C) 1998 Elsevier Sc ience B.V. All rights reserved.