Mechanism of Inhibition to Fusarium moniliforme by Antimicrobial Peptide Fengycins

Abstract:

Fengycin is a cyclic lipopeptide antibiotic produced nonribosomally by Bacillus subtilis. In this study, the primary mechanism of inhibition to Fusarium moniliforme by Fegycins was investigated according to their special properties. Microscopic observation on morphology of F. moniliforme mycelia revealed that tips of partial mycelia were lysed. PI staining of Fengycins-treated F. moniliforme mycelia was observed under fluorescence microscope, which indicated the toxin-mediated damage of cytoplasmic membrane. Further study showed that addition of chitin, chitosan, β-1,3-glucan, ergosterol and cholesterol in agar media could not significantly modify the inhibition to F. moniliforme by Fengycins, while addition of phosphatidylcholine could antagonize the antifungal activity of Fengycins. These results suggested that phosphatidylcholine probably was the plasma membrane target for Fengycins. Additionally, our results also showed that fengycins could depress the activity of PLA2 secreted by F. moniliforme, which might contribute to the antifungal activity of fengycins against F. moniliforme.

Key words:Fengycins, Fusarium moniliforme, Mechanism of inhibition