Emilia Matallana, Agustín Aranda and Beatriz Vallejo

The thesis, directed by Agustín Aranda and Emilia Matallana, tries to elucidate the molecular mechanisms of adaptation of industrial wine strains to the available nutrients. Part of the results have been published in the journals FEMS Yeast Research and Scientific Reports. The thesis was defended on January 31, 2020.

Living beings have complex systems for integrating information about environmental conditions, especially the availability of nutrients. In model systems, such as the yeast Saccharomyces cerevisiae, these signaling pathways have been studied in depth under laboratory conditions. However, very little is known about these processes under industrial conditions. The central objective of the thesis, entitled “Analysis of nutrient signaling pathways in wine strains of Saccharomyces cerevisiae under winemaking conditions”, has been to understand how yeasts respond to adverse conditions of nutrient availability in the must. Wine strains show patterns of biochemical responses different from those in the laboratory and in this research strategies, such as directed evolution or specific mutation of components of signaling pathways, have been used to understand these differential behaviors. In this sense, molecular targets have been identified for the improvement of industrial wine strains. The results obtained also demonstrate that there is no strict division between carbon and nitrogen nutrient signaling in winemaking, but rather a regulated cross-communication between all signaling pathways that allows the cellular metabolism to be adapted to environmental conditions.

Beatriz Vallejo's doctoral thesis, initiated at the Institute of Agrochemistry and Food Technology (IATA, CSIC), has been completed in the Industrial Yeast Biotechnology group of the I²SysBio under the supervision of Agustín Aranda (Senior Scientist of the CSIC) and Emilia Matallana (professor of Biochemistry and Molecular Biology at the University of Valencia). Furthermore, for three months, Beatriz Vallejo stayed at the Oenology Unit of the Institute of Vine and Wine Sciences of the University of Bordeaux. Throughout the development of her doctoral research, she was hired by the University Teacher Training Program (FPU) of the Ministry of Education. The panel was made up of Ramón González (Institute of Vine and Wine Sciences, CSIC, La Rioja), Mª Ángeles de la Torre (Institut de Recerca Biomèdica, Universitat de Lleida) and José Manuel Guillamón (IATA, CSIC, València), who rated the thesis as outstanding.