title: Physiological Effects of GLT1 Modulation in Saccharomyces cerevisiae Strains Growing on Different Nitrogen Sources.
abstract: Saccharomyces cerevisiae is one of the most employed cell factories for the production of bioproducts. Although monomeric hexose sugars constitute the preferential carbon source, this yeast can grow on a wide variety of nitrogen sources that are catabolized through central nitrogen metabolism (CNM). To evaluate the effects of internal perturbations on nitrogen utilization, we characterized strains deleted or overexpressed in GLT1, encoding for one of the key enzymes of the CNM node, the glutamate synthase. These strains, together with the parental strain as control, have been cultivated in minimal medium formulated with ammonium sulfate, glutamate, or glutamine as nitrogen source. Growth kinetics, together with the determination of protein content, viability, and reactive oxygen species (ROS) accumulation at the single cell level, revealed that GLT1 modulations do not significantly influence the cellular physiology, whereas the nitrogen source does. As important exceptions, GLT1 deletion negatively affected the scavenging activity of glutamate against ROS accumulation, when cells were treated with H2O2, whereas Glt1p overproduction led to lower viability in glutamine medium. Overall, this confirms the robustness of the CNM node against internal perturbations, but, at the same time, highlights its plasticity in respect to the environment. Considering that side-stream protein-rich waste materials are emerging as substrates to be used in an integrated biorefinery, these results underline the importance of preliminarily evaluating the best nitrogen source not only for media formulation, but also for the overall economics of the process.
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2 - 20126 Milan, Italy.|SYSBIO - Centre of Systems Biology, Milano and Roma, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Brambilla
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2 - 20126 Milan, Italy.|SYSBIO - Centre of Systems Biology, Milano and Roma, Italy.
authors.forename: Giusy Manuela
authors.initials: GM
authors.lastname: Adamo
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2 - 20126 Milan, Italy.|SYSBIO - Centre of Systems Biology, Milano and Roma, Italy.
authors.forename: Gianni
authors.initials: G
authors.lastname: Frascotti
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2 - 20126 Milan, Italy.|SYSBIO - Centre of Systems Biology, Milano and Roma, Italy.
authors.forename: Danilo
authors.initials: D
authors.lastname: Porro
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2 - 20126 Milan, Italy.|SYSBIO - Centre of Systems Biology, Milano and Roma, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Branduardi
mesh_terms: D050260:Carbohydrate Metabolism; D002241:Carbohydrates; D003470:Culture Media / Q000737:chemistry; D017353:Gene Deletion; D005800:Genes, Fungal / Q000235:genetics* / Q000502:physiology; D005970:Glutamate Synthase / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D009584:Nitrogen / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D002241:Carbohydrates; D003470:Culture Media; D017382:Reactive Oxygen Species; D005973:Glutamine; D018698:Glutamic Acid; D006861:Hydrogen Peroxide; D005970:Glutamate Synthase; D009584:Nitrogen
keywords: Ammonium sulphate; Central Nitrogen Metabolism; GLT1; Glutamate; Glutamine; Saccharomyces cerevisiae