Brettanomyces is a genus of yeasts. Brettanomyces occur naturally on the skins of grapes in the vineyard. These ‘wild’ yeasts are often undesirable because they can provide animal aromas in the wine (horse stable and wet leather). Therefore, the must is often inoculated with Saccharomyces cerevisiae yeasts (standard culture yeasts) during vinification to prevent Brettanomyces from multiplying. Too great an influence of aromas in the wine produced by Brettanomyces yeasts can lead to wine faults, see also ‘brett’.