Transcriptomic and proteomic analysis of Oenococcus oeni PSU-1 response to ethanol shock.

The correct development of malolactic fermentation depends on the capacity of Oenococcus oeni to survive under harsh wine conditions. The presence of ethanol is one of the most stressful factors affecting O. oeni performance. In this study, the effect of ethanol addition (12% vol/vol) on O. oeni PSU-1 has been evaluated using a transcriptomic and proteomic approach. Transcriptomic analysis revealed that the main functional categories of the genes affected by ethanol were metabolite transport and cell wall and membrane biogenesis. It was also observed that some genes were over-expressed in response to ethanol stress (for example, the heat shock protein Hsp20 and a dipeptidase). Proteomic analysis showed that several proteins are affected by the presence of ethanol. Functions related to protein synthesis and stability are the main target of ethanol damage. In some cases the decrease in protein concentration could be due to the relocation of cytosolic proteins in the membrane, as a protective mechanism. The omic approach used to study the response of O. oeni to ethanol highlights the importance of the cell membrane in the global stress response and opens the door to future studies on this issue.