Detoxification capabilities of copper and pesticides by winemaking yeasts

Viticulture stands out as an agricultural sector most reliant on xenobiotic substances for plant protection from fungal diseases and pest attacks, employing pesticides in conventional farming and copper in organic practices. These compounds are then found in grape juice and wine, causing a major health concern, as well as negatively affecting the fermentation process. Current methods for addressing this issue, relying on adsorbents, metal-chelating polymers, or thermovinification, often lack efficiency and present environmental drawbacks associated with energy consumption or chemical inputs. Based on the reported sorption capacities of yeasts, treatment of the harvest with non-Saccharomyces (NS) strains emerges as a biological alternative for the elimination of xenobiotics from grape musts. In this context, this study aims to provide a global perspective on the variability of relationships and interactions occurring between yeasts from the winemaking environment and xenobiotic compounds during the early stages of the process. To this end, the incidence of xenobiotics (a mix of twenty-three pesticides commonly used in the vineyard or copper) on the fermentative activity of thirteen strains of Saccharomyces and NS yeasts in synthetic must, and, conversely, the capacity of xenobiotic detoxification of these yeasts was investigated. A comparative study based on conducting fermentations in the presence or absence of xenobiotics first demonstrated that the presence of copper did not significantly influence the growth and fermentation dynamics of the various yeast strains examined, with the notable exception of an NS strain. In contrast, the growth and fermentative capacities of all yeast strains were negatively affected by pesticide exposure, exhibiting strain-specific responses. Most strains could efficiently remove copper initially present in the medium, with a rate depending on the growth capability of the strains and retained copper even after losing viability. The studied yeasts were also capable of removing pesticides from the medium, but with an efficiency that differed according to the strain and the pesticide type. Some pesticides resisted detoxification (folpel), while others (zoxamide or cyazofamid) were eliminated by all strains. Furthermore, NS yeast demonstrated stronger detoxification capabilities than Saccharomyces cerevisiae, indicating its potential for the pre-fermentation detoxification of grape musts.