p-coumaric acid induces Brettanomyces bruxellensis death under winemaking conditions

Brettanomyces bruxellensis is a significant spoilage yeast in wine, known for producing volatile phenols that alter wine aroma and quality. These compounds are formed from hydroxycinnamic acids (HCA), including ferulic, p-coumaric, and caffeic acids, which are naturally present in grapes and in wine. HCA conversion to ethyl phenols is an original and conserved characteristic of B. bruxellensis that results from the presence of a two-step pathway. We hypothesized HCA conversion serves as a detoxification strategy for B. bruxellensis. This study investigated how different HCA concentrations affect growth and viability of 24 B. bruxellensis strains, with a particular focus on two wine-isolated strains (L1760 and 2OT13_02). Under wine-like conditions, only p-coumaric acid exhibited a cytotoxic effect, affecting growth, cell viability, and the conversion of HCA to vinylphenol (VP) and ethylphenol (EP) in a concentration-dependent manner. This effect was specifically induced by p-coumaric acid itself, rather than by its VP or EP derivatives. It was more pronounced at pH 3.3, likely due to enhanced diffusion of the acidic form across yeast membrane. The two strains showed a similar behavior, although with a different degree of tolerance. Sensitivity of the 24-strain panel to HCA showed a large diversity, possibly linked to genetic traits. Our findings highlight the potential of using naturally occurring wine compounds like p-coumaric acid as part of an integrated strategy to control B. bruxellensis population in wine.