A Comparative Proteomic Analysis of the Acetification Process of Komagataeibacter europaeus Using Different Substrates

Although vinegar is technically elaborated by a well-known bioprocess, the behavior and function of the microorganisms responsible for its production still need investigation. In vinegars obtained from raw materials and systems typical of Europe, the acetic acid bacteria species Komagataeibacter europaeus predominates due to its particular adaptive metabolism. This work addresses the study of several adaptation mechanisms of K. europaeus during acetic acid fermentation in a submerged semi-continuous production system. The aim is to analyze the molecular response and behavior of this species to increasing acidity gradients, up to 7–8% w/v acetic acid, applying a comparative proteomic approach in three matrices (synthetic alcoholic medium, dark craft beer, and dry fine wine). A total of 1070 proteins are identified, with 174 showing statistically significant changes in abundance (FDR < 0.05), particularly in pathways related to amino acid biosynthesis, fatty acid metabolism, and stress response. The proteomic patterns differ among substrates, with the synthetic alcohol medium inducing stress-related proteins and the dark craft beer enhancing lipid biosynthesis. These observations provide experimental evidence that the fermentation substrate modulates metabolic adaptation in K. europaeus, offering a rational basis for designing fermentation protocols that enhance bacterial resilience, thereby optimizing vinegar production processes.