Impact of inhibitory peptides released by Saccharomyces cerevisiae BDX on the malolactic fermentation performed by Oenococcus oeni Vitilactic F

• S. cerevisiae BDX inhibits O. oeni Vitilactic F during sequential fermentations.
• The inhibition is reproducible in natural and synthetic grape juices.
• An extracellular 5–10 kDa yeast peptidic fraction inhibits the malolactic fermentation.
• The 5–10 kDa fraction isolated from late stationary phase is the most inhibitory.
• The 5–10 kDa fraction targets directly the malolactic enzyme activity.

A previous study has shown that the malolactic fermentation (MLF) was inhibited during sequential fermentations performed with the pair Saccharomyces cerevisiae BDX/Oenococcus oeni Vitilactic F in synthetic grape juices. A yeast peptidic fraction with an apparent MW of 5–10 kDa was involved in the inhibition. In the present study, the MLF was also inhibited in Cabernet Sauvignon and Syrah wines. The inhibition due to the peptidic fraction was maintained despite high phenolic contents. Kinetic studies showed that the peptidic fraction was gradually released during the alcoholic fermentation (AF). Its highest anti-MLF effect was reached when isolated from late stages of the AF stationary phase. The peptidic fraction was tested in vitro on cell-free bacterial cytosolic extracts containing the malolactic enzyme in a pH range between 3.5 and 6.7. Results showed that it was able to directly inhibit the malolactic enzyme activity with an increasing inhibitory kinetic correlated to the AF time at which it was collected.