Antimicrobial action of synthetic peptides towards wine spoilage yeasts

The antimicrobial action of selected short synthetic peptides against wine spoilage yeasts such as Cryptococcus albidus, Dekkera bruxellensis, Pichia membranifaciens, Saccharomyces cerevisiae, Zygosaccharomyces bailii and Zygosaccharomyces bisporus has been examined. Peptides analyzed include nine sequence-related antifungal hexapeptides (PAFs) previously developed by a combinatorial approach, and two representative lactoferricin B (LfcinB)-derived peptides. Different peptides had distinct activity profiles. In vitro assays identified the peptides PAF26, PAF36, and LfcinB(17-31), as having growth inhibitory properties towards several of the yeasts at low micromolar concentrations. Z. bailii and Z. bisporus were the most sensitive yeasts. In addition to their fungistatic activity, the three peptides showed fungicidal properties towards Z. bailii, Z. bisporus, and S. cerevisiae in laboratory growth medium. Remarkably, only LfcinB(17-31) against Z. bisporus had inhibitory and fungicidal properties in wine at the concentrations assayed, showing that the antimicrobial action of each peptide is dependent on both the food matrix and the target micro-organism. Lack of fungicidal activity of peptides against Z. bailii in wine is related to the presence of salt ions other than divalent cations. On the contrary, fungicidal activity of LfcinB(17-31) towards Z. bisporus was not significantly affected by wine salts. Our data identify a bioactive peptide from natural origin with potential use against the food spoilage yeast Z. bisporus, and indicate that the application of antimicrobial peptides in wine preservation deserves further investigation.