Objectives: Subclass IIa bacteriocins are characterized by a hydrophilic N-terminal domain that shares a YGNGVxCxxxxC consensus and a variable hydrophobic C-terminus. Enterocin CRL35 is a 43- amino-acid heat stable peptide with antilisterial activity. Short synthetic peptides derived from the N-terminal half of enterocin CRL35 and other subclass IIa bacteriocins were evaluated for antimicrobial properties.
Methods: In vitro activities of synthetic peptides were evaluated in complex, chemically defined and minimal media. MIC assays were performed by the agar well-diffusion method. Fluorescence assays to evaluate the dissipation of membrane potentials in intact cells were carried out. Time–kill kinetics of Listeria innocua cells with the active peptide were performed.
Results and conclusions: A 15-mer peptide derived from enterocin CRL35 inhibited the growth of L. innocua and Listeria monocytogenes in synthetic/minimal media and dissipated the membrane potential of sensitive cells, with MICs of 10 and 50 µM, respectively. 15-mer derivatives from other class IIa bacteriocins (mesentericin Y105, pediocin PA-1 and piscicolin 126) also showed antimicrobial activities.