title: Management of Multiple Nitrogen Sources during Wine Fermentation by Saccharomyces cerevisiae.
abstract: During fermentative growth in natural and industrial environments,Saccharomyces cerevisiaemust redistribute the available nitrogen from multiple exogenous sources to amino acids in order to suitably fulfill anabolic requirements. To exhaustively explore the management of this complex resource, we developed an advanced strategy based on the reconciliation of data from a set of stable isotope tracer experiments with labeled nitrogen sources. Thus, quantifying the partitioning of the N compounds through the metabolism network during fermentation, we demonstrated that, contrary to the generally accepted view, only a limited fraction of most of the consumed amino acids is directly incorporated into proteins. Moreover, substantial catabolism of these molecules allows for efficient redistribution of nitrogen, supporting the operativede novosynthesis of proteinogenic amino acids. In contrast, catabolism of consumed amino acids plays a minor role in the formation of volatile compounds. Another important feature is that the α-keto acid precursors required for thede novosyntheses originate mainly from the catabolism of sugars, with a limited contribution from the anabolism of consumed amino acids. This work provides a comprehensive view of the intracellular fate of consumed nitrogen sources and the metabolic origin of proteinogenic amino acids, highlighting a strategy of distribution of metabolic fluxes implemented by yeast as a means of adapting to environments with changing and scarce nitrogen resources.IMPORTANCEA current challenge for the wine industry, in view of the extensive competition in the worldwide market, is to meet consumer expectations regarding the sensory profile of the product while ensuring an efficient fermentation process. Understanding the intracellular fate of the nitrogen sources available in grape juice is essential to the achievement of these objectives, since nitrogen utilization affects both the fermentative activity of yeasts and the formation of flavor compounds. However, little is known about how the metabolism operates when nitrogen is provided as a composite mixture, as in grape must. Here we quantitatively describe the distribution through the yeast metabolic network of the N moieties and C backbones of these nitrogen sources. Knowledge about the management of a complex resource, which is devoted to improvement of the use of the scarce N nutrient for growth, will be useful for better control of the fermentation process and the sensory quality of wines.
authors.affiliation: SPO, INRA, SupAgroM, Université de Montpellier, Montpellier, France.
authors.forename: Lucie
authors.initials: L
authors.lastname: Crépin
authors.affiliation: SPO, INRA, SupAgroM, Université de Montpellier, Montpellier, France.
authors.forename: Nhat My
authors.initials: NM
authors.lastname: Truong
authors.affiliation: SPO, INRA, SupAgroM, Université de Montpellier, Montpellier, France.
authors.forename: Audrey
authors.initials: A
authors.lastname: Bloem
authors.affiliation: SPO, INRA, SupAgroM, Université de Montpellier, Montpellier, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Sanchez
authors.affiliation: SPO, INRA, SupAgroM, Université de Montpellier, Montpellier, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Dequin
authors.affiliation: SPO, INRA, SupAgroM, Université de Montpellier, Montpellier, France camarasa@supagro.inra.fr.
authors.forename: Carole
authors.initials: C
authors.lastname: Camarasa
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D018533:Biomass; D002244:Carbon / Q000378:metabolism; D003470:Culture Media / Q000032:analysis; D005285:Fermentation; D019649:Food Industry; D005516:Food Microbiology; D000067030:Fruit and Vegetable Juices; D007553:Isotope Labeling; D053858:Metabolic Networks and Pathways; D008660:Metabolism; D009584:Nitrogen / Q000737:chemistry* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism*; D000073893:Sugars / Q000378:metabolism; D027843:Vitis / Q000737:chemistry; D014920:Wine / Q000032:analysis / Q000382:microbiology*
chemical_list: D000596:Amino Acids; D003470:Culture Media; D000073893:Sugars; D002244:Carbon; D009584:Nitrogen
keywords: complex nitrogen resource; metabolic network; metabolism; nitrogen; quantitative analysis; regulation; yeasts