Understanding volatile phenol production in fermented beverages – UnderPhe

Understanding volatile phenol production in fermented beverages

The main scientific questions addressed in this project are to understand what are the physiological benefits of volatile phenol formation for Brettanomyces bruxellensis and Brettanomyces anomalus strains and how this production makes these species more competitive in stressful environments, in relation to genetic diversity.

General objectives and main issues

With an increasingly competitive international market, the French fermented beverage industry is seeking sustainable solutions to meet the current challenges of sustainability, adaptation to climate change and evolution of consumer practices towards high-quality products. During the production of these beverages, the metabolic activity of micro-organisms results in the formation of a wide range of compounds that contribute, favourably or not, to their sensory properties. Thus, the development of innovative fermentation processes requires an in-depth understanding of the physiology of the different microbial actors, in order to better control them and/or exploit their potentialities. <br />Brettanomyces yeasts (Brettanomyces bruxellensis and Brettanomyces anomalus) coexist with Saccharomyces cerevisiae in many fermentation processes, but differ in specific characteristics. Most notable is its ability to produce volatile phenols, a major fault in wines but desirable in some types of beer. Controlling the formation of volatile phenols thus appears clearly challenging for the entire field of fermented beverages. However, this issue is difficult to address due to important gaps in the knowledge of Brettanomyces species physiology.<br />In this context, our research project endeavours to elucidate the metabolic and molecular origin of volatile phenol production by B. bruxellensis and B. anomalus in cider, wine and beer and to investigate their regulation by environmental and technological factors. <br />More specifically, we intend:<br />- to provide a comprehensive picture of the diversity and specificities of the metabolism of B. bruxellensis and B. anomalus species and to elucidate the underlying genetic determinants, in particular by establishing the links between genotype and phenotype.<br />- to situate the formation of volatile phenols in the overall metabolic scheme of this yeast and elucidate its physiological role and its relationship with growth or species dissemination.<br />- to deeply examine the response mechanisms of Brettanomyces strains to changes in culture conditions in terms of growth, central metabolism and production of volatile phenols in order to identify the factors that regulate the metabolism of B. bruxellensis and B. anomalus.<br />Based on these data, to design innovative and sustainable beverage production methods to handle the formation of volatile phenols during wine, cider and beer elaboration.<br />In addition, the integrated analysis of the information generated throughout the project may allow us to identify gene functions and will provide new information for understanding how ethylphenol production makes B. bruxellensis and B. anomalus competitive species in harsh environments and the basis for their adaptation.