Dual Mode of Action of Amylolysin: A Type-B Lantibiotic Produced by Bacillus amyloliquefaciens GA1

The partial genome sequencing of Bacillus amyloliquefaciens GA1 led to the identification of the aml gene cluster involved in the synthesis of the novel lantibiotic named amylolysin. Pure amylolysin was shown to have an antibacterial activity toward Gram-positive bacteria including methicillin resistant Staphylococcus aureus. The lantibiotic was also found efficient to inhibit the growth of Listeria monocytogenes strains on poultry meat upon a long storage at 4°C. In silico analyses of the aml gene cluster revealed the presence of a characteristic motif involved in interaction with peptidoglycan precursor lipid II. In the present work, this interaction was further investigated using the LiaRS based reporter gene that is able to sense specifically antibiotics that interfere with lipid II cycle. Beside this, the pore-forming ability of amylolysin was evidenced by means of membrane depolarization measurements and cell leaking experiments.