Exploring copper’s role in metabolic modulation of Lachancea thermotolerans in winemaking conditions

Abstract

The phenomenon of global warming has been demonstrated to induce the premature ripening of grapes, resulting in a concomitant increase in sugar and a decrease in acidity. This can result in the production of wines that are characterised by an imbalance in terms of alcohol content and acidity. The utilisation of lactic acid-producing Lachancea thermotolerans yeast in fermentation represents a promising strategy for reducing the pH of must without the need for chemical acidification. However, it is important to note that the fermentation rate and lactic acid production can be influenced by several factors present in the must. The present study focused on the effect of copper, utilised in organic vineyards to limit mildew, on biomass and lactic acid production by two L. thermotolerans oenological strains in laboratory-scale fermentations. The results obtained demonstrated that the addition of copper resulted in increased lactic acid production in comparison with the control condition and this effect was strain-dependent. The results of the microbiological follow-up, which was carried out using classical microbiological methods in conjunction with flow cytometry, demonstrate discrepancies in the fermentation kinetics in conditions exhibiting varying concentrations of copper. Furthermore, the analysis of the samples using flow cytometry revealed the oxidative status of the two strains throughout the fermentation process. Transcriptomic data indicates that certain metabolic pathways of L. thermotolerans are induced by the presence of copper, with hypothesises about ribosomal and parietal activities in addition to cell communication. The findings of this study demonstrate strain-specific effects of copper on L. thermotolerans, which may be of interest to winemakers, particularly those engaged in organic viticulture who intend to utilise acidifying yeasts during warm vintages.

References

Simonin, S.; Sizzano, F.; Bianconi, V.; Monnard, C.; Schnée, S.; Bourdin, G.; Alfonso E.; Bach, B. (2026). Exploring copper’s role in metabolic modulation of Lachancea thermotolerans in winemaking conditions. (in review).