Abstract: Since the beginning of this century, non-Saccharomyces yeast starters are gaining market share in the winemaking industry. They should commonly be combined with Saccharomyces cerevisiae to avoid incomplete fermentation. In this context, the potential interactions among yeast starters can impact the outcome of wine fermentation. Our previous research has demonstrated that S. cerevisiae shows transcriptional responses to the presence of other yeast species, with both common and species-specific features (Curiel et al., 2017). The timing of these responses suggests there are interspecies communication mechanisms involved. In this work we test the hypothesis that extracellular vesicles (EVs) play a role in these interactions. S. cerevisiae cultures were exposed to EVs from Metschnikowia pulcherrima. We then evaluated the impact of these EVs on the physiology of S. cerevisiae by RNAseq analysis and compared the results to the response of S. cerevisiae to living M. pulcherrima cells under the same experimental conditions. The sample time for transcriptomic analysis was three hours, to minimize the impact of purely metabolic interactions. Our analysis reveals very similar responses of S. cerevisiae to either M. pulcherrima cells or its EVs. Both appear to induce transcription of genes related to glycolysis and ribosomal activity and repress genes involved in autophagy. These results confirm that S. cerevisiae responds to competing species under wine-like conditions, in a way not mediated by nutrient competition or major fermentation metabolites, and provide the first experimental support for the hypothesis that recognition mechanisms involve, at least in part, EVs.

This work was funded by the Spanish Government through grant PID2019-105159RB-I00 funded by MCIN/AEI/10.13039/501100011033, grant BES-2016- 077557, and grant PRE2020-093420 funded by MCIN/AEI/10.13039/501100011033 and by ¿ESF Investing in your future¿ (training contracts for AM and MM). JT was funded by FGCSIC by the COMFUTURO program.

Trabajo presentado en el XVIII Congreso de la Sociedad Española de Biotecnología, celebrado en Madrid del 17 al 20 de junio de 2023