Differential Impact of Ergosterol on Yeast Membranes Exposed to Membrane-Targeting Antimicrobial Compounds

Concerns with fungal plant pathogen resistance to fungicides require sustainable alternatives. Model yeast lipid membranes were used to assess the role of ergosterol in the activity of antimicrobials known to affect biomembranes. Results showed that nystatin decreased yeast liposome stability as ergosterol content increased, whereas iturin effects were consistently high, but did not appear to be affected by ergosterol content. Nisin tended to decrease yeast liposome stability as ergosterol content increased, albeit much less than nystatin, and caused increased liposome size at lower ergosterol content. ζ-Potential values indicated that liposomes were highly stable to surfactin, regardless of the overall impact of the tested ergosterol concentrations. There was an increase in liposome stability to fengycin with increased ergosterol content. The findings provide insights into the role of ergosterol in the efficacy and mechanistic activity of these antimicrobials.