title: The simultaneous biosynthesis and uptake of amino acids by Lactococcus lactis studied by (13)C-labeling experiments.
abstract: Uniformly (13)C labeled glucose was fed to a lactic acid bacterium growing on a defined medium supplemented with all proteinogenic amino acids except glutamate. Aspartate stemming from the protein pool and from the extracellular medium was enriched with (13)C disclosing a substantial de novo biosynthesis of this amino acid simultaneous to its uptake from the growth medium and a rapid exchange flux of aspartate over the cellular membrane. Phenylalanine, alanine, and threonine were also synthesized de novo in spite of their presence in the growth medium.
authors.affiliation: Center for Process Biotechnology, Department of Biotechnology, Building 223, Technical University of Denmark, DK-2800 Lyngby, Denmark.
authors.forename: Niels Bang Siemsen
authors.initials: NB
authors.lastname: Jensen
authors.forename: Bjarke
authors.initials: B
authors.lastname: Christensen
authors.forename: Jens
authors.initials: J
authors.lastname: Nielsen
authors.forename: John
authors.initials: J
authors.lastname: Villadsen
mesh_terms: D000409:Alanine / Q000096:biosynthesis / Q000493:pharmacokinetics; D000596:Amino Acids / Q000096:biosynthesis* / Q000493:pharmacokinetics*; D001224:Aspartic Acid / Q000737:chemistry / Q000378:metabolism*; D018533:Biomass; D002462:Cell Membrane / Q000378:metabolism; D003198:Computer Simulation; D003470:Culture Media; D008401:Gas Chromatography-Mass Spectrometry; D018698:Glutamic Acid / Q000378:metabolism; D007553:Isotope Labeling / Q000379:methods; D013294:Lactococcus lactis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D008954:Models, Biological; D008956:Models, Chemical; D010649:Phenylalanine / Q000096:biosynthesis / Q000493:pharmacokinetics; D013912:Threonine / Q000096:biosynthesis / Q000493:pharmacokinetics
chemical_list: D000596:Amino Acids; D003470:Culture Media; D013912:Threonine; D001224:Aspartic Acid; D018698:Glutamic Acid; D010649:Phenylalanine; D000409:Alanine