Influence of nitrogen source on fermentation and higher alcohol production by an industrial strain of Saccharomyces cerevisiae: The Isoleucine case

Doctoral Thesis / Dissertation from the year 2012 in the subject Biology - Genetics / Gene Technology, Federal Rural University of Pernambuco (Institut National des Sciences Appliquées), course: Genetics, language: English, abstract: Uncover the secrets behind crafting the perfect flavor in alcoholic beverages! Delve into the intricate world of Saccharomyces cerevisiae and its metabolic dance with nitrogen, where the choice of nutrient becomes the conductor of fermentation. This groundbreaking study meticulously examines how different nitrogen sources-from the common ammonium to the complex amino acids like leucine, isoleucine, valine, tryptophan, and phenylalanine-orchestrate the production of higher alcohols, those enigmatic compounds that define the very essence of a drink's aroma and taste. Journey through meticulously designed experiments using both industrial (JP1) and laboratory (CEN.PK113) strains to witness firsthand the profound impact of nitrogen on fermentation kinetics, unveiling how growth rates and doubling times are dramatically influenced by nutrient selection. Explore the fascinating Ehrlich pathway, the established route to higher alcohol formation, while simultaneously unraveling the mysteries behind unexpected alcohol production, potentially linked to metabolic overflow, amino acid leakage, and the hidden roles of mitochondrial compartments. This research dives deep into gene transcription patterns, providing a molecular-level understanding of how nitrogen dictates the expression of genes crucial for higher alcohol biosynthesis, opening avenues for precision metabolic engineering. Discover how manipulating nitrogen sources can become a powerful tool for controlling higher alcohol levels, ultimately shaping the sensory profile of beverages like cachaça and beyond. With detailed analysis of growth rates, glucose consumption, ethanol and acetate production, and the quantification of various higher alcohols, this thesis provides invaluable insights

Esteban Espinosa Vidal was born in Mar del Plata, Buenos Aires, Argentina, on the 5 td of February 1974. He attended the National Media Education School and matriculated in 1991. In 2000, he worked for one year in the Molecular breeding Laboratory at Monsanto Company. In 2004, he obtained a degree in Biological Sciences with specialized in Molecular Biology from the National Mar del Plata University. Esteban obtained a Master degree of Science in Genetic from Federal University of Pernambuco (UFPE) in 2008, and a Doctor degree of Science in Genetic from the same institution (UFPE) in 2012. Actually, he is working in his Post-Doctorate in the Centre for Strategic Technologies of Northeast (CETENE/MCTI), where he coordinates the Bioprocess laboratory, the Phytoquimic and chemical process laboratory and the Analytical Central laboratory from 2013. He belongs to the Interdepartmental research group of metabolic Metabolic Engineering of the UFPE (NEM) and he is the leader of the Research Groups in Biotechnology White (GBioB) and the Group for Research and Development of Analytical Methods (NPDMA). He is a member of Science and Technology Commission of CETENE/MCTI from 2014. His principal interest involves nitrogen metabolism, higher alcohols and ester metabolism production, microorganism biodiversity, physiology and improvement of industrial yeasts for first and second ethanol production, yeast gene expression and regulation analysis, and purification, identification and quantification of active compounds. He has experience in the area of molecular biology, fermentation, physiology of industrial microorganisms, in gene expression analysis, and in the identification and quantification of metabolites by high performance chromatography and mass spectrometry.