Role of Lipid Composition in the Interaction and Activity of the Antimicrobial Compound Fengycin with Complex Membrane Models

Fengycins are compounds produced by bacteria of the Bacillus genus with strong antifungal activity. In this work, lipids extracted from fungal and oomycetal molds were used to assess the ability of fengycin to bind and insert into complex membrane models prepared as Langmuir lipid monolayers. In addition, fengycin-induced leakage in liposomes prepared from these complex lipid extracts was also evaluated. Fengycin’s ability to bind and incorporate into these membranes seemed to be mainly related to ergosterol content. Other membrane characteristics such as phospholipid fatty acyl chain length played a more peripheral role. A high ergosterol concentration appeared to allow other membrane characteristics generally associated with fengycin binding and/or insertion, such as higher proportion of phosphatidylcholine head groups or increased fatty acyl unsaturation, to be present without adversely affecting membrane integrity. Increased membrane leakage was also generally associated with the presence of low or no ergosterol. Leakage was also correlated with the previously reported biological activity of fengycin on these molds.