Molecular adaptation response of Oenococcus oeni in non-Saccharomyces fermented wines: A comparative multi-omics approach.

Oenococcus oeni is the main agent responsible for malolactic fermentation (MLF) in wine. This usually takes place in red wines after alcoholic fermentation (AF) carried out by Saccharomyces cerevisiae. In recent years, there is an increasing interest in using non-Saccharomyces yeast, usually in combination with S. cerevisiae, to improve wine quality. Current studies report a stimulatory effect of non-Saccharomyces on MLF, generally related to a decrease in the inhibitor compounds found in wine. In this work, we followed a comparative multi-omics approach, including transcriptomic and proteomic analysis, to study the molecular adaptation of O. oeni in wines fermented with Torulaspora delbrueckii and Metschnikowia pulcherrima, two of the most frequently used non-Saccharomyces, in sequential inoculation with S. cerevisiae. We compared the results to the adaptation of O. oeni in S. cerevisiae wine to determine the main changes arising from the use of non-Saccharomyces. The duration of MLF was shortened when using non-Saccharomyces, to half the time with T. delbrueckii and to a quarter with M. pulcherrima. In this work, we observed for the first time how O. oeni responds at molecular level to the changes brought about by non-Saccharomyces. We showed a differential adaptation of O. oeni in the wines studied. In this regard, the main molecular functions affected were amino acid and carbohydrate transport and metabolism, from which peptide metabolism appeared as a key feature under wine-like conditions. We also showed that the abundance of Hsp20, a well-known stress protein, depended on the duration time. Thus, the use of non-Saccharomyces reduced the abundance of Hsp20, which could mean a less stressful wine-like condition for O. oeni.