Proteomic yeast stress response to pressure in a final stage in the second fermentation during sparkling wine elaboration

Spanish sparkling wine or cava (Certified Brand of Origin) elaborated following the “champenoise” method undergoes a second fermentation in closed bottles of base wine, followed by aging of wines with lees of at least 9 months. Both processes are considered as important factors contributing to the quality of cava. During the second fermentation, yeasts are subjected to pressure in which the response of the yeast cells have not been still clearly elucidated. The objective of this study is to identify proteins that may participate in the response to pressure. OFFGEL fractionator coupled to LTQ Orbitrap XL MS equipment were used trying to detect the maximum possible number of proteins in yeasts grown in a traditional second fermentation condition and under a reference condition not subjected to pressure. The obtained proteomic profiles show 679 proteins detected under the first condition while 979 under the reference condition. From the total number of proteins identified under the second fermentation with pressure, 251 were just detected under it being mainly ribosomal and extracellular; and involved in biological processes such as ribosome assembly, cytoplasmic translation or organelle assembly. The cellular components and biological processes mentioned in this study may be essential for the fermenting yeast survival in a condition such as second fermentation during sparkling wine elaboration. Genetic experiments are needed to definitively confirm the necessity of these proteins synthesis under pressure.