Susceptibility of Listeria monocytogenes to antimicrobial peptides

We assessed the susceptibility of several pathogenic and non-pathogenic Listeria species to antimicrobial peptides of animal and plant origin. Human defensins and thionins were highly inhibitory, whereas prolamine, snakin and magainin showed an intermediate effect. A temperature dependence in the activity of potato defensin was observed for Listeria monocytogenes and Listeria ivanovii. PrfA* L. monocytogenes mutants, that overexpress constitutively PrfA-dependent genes, were sensitive to the peptide independently of the temperature whereas isogenic PrfA(-) derivatives were constitutively resistant. These data indicate that the thermoregulated transcription factor PrfA controls the expression of bacterial products that influence the susceptibility or resistance to some antimicrobial peptides. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.