Protein content of the Oenococcus oeni extracellular vesicles-enriched fraction

Abstract

Malolactic fermentation is essential for the quality of red wines and some other wine styles. This process consists in the decarboxylation of L-malic acid to L-lactic acid, increasing the pH of wine and releasing compounds with sensory impact [1]. Spontaneous malolactic fermentation is often driven by Oenococcus oeni, and commercial starters for this purpose are also often of this species. The microbial interactions during wine fermentation are a growing field of interest due to the new inoculation strategies in winemaking processes. Among other interaction mechanisms, extracellular vesicles (EVs) might play a relevant role on it. Determination of the protein cargo of the EVs is a first approach to understand how biological processes can be affected in by the EVs. In this work, the production of extracellular vesicles by O. oeni is reported for the first time. The protein content of O. oeni EVs was characterised by proteomic analysis. It shares some characteristics with the recently described protein content of Lactiplantibacillus plantarum EVs [3], a bacterial species also capable of performing malolactic fermentation of wine. EVs produced by O. oeni are similar in size to other bacterial EVs described previously, and the proteomic analysis shows an enrichment in ribosomal and integral membrane proteins, which are in accordance with other bacterial and eukaryotic EV cargo. Considering ubiquity of O. oeni in winemaking, this work will help in future studies on microbial interactions relevant for this industry.

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