title: Systems-wide analysis and engineering of metabolic pathway fluxes in bio-succinate producing Basfia succiniciproducens.
abstract: Basfia succiniciproducens has been recently isolated as novel producer for succinate, an important platform chemical. In batch culture, the wild type exhibited a high natural yield of 0.75 mol succinate (mol glucose)⁻¹. Systems-wide ¹³C metabolic flux analysis identified undesired fluxes through pyruvate-formate lyase (PflD) and lactate dehydrogenase (LdhA). The double deletion strain B. succiniciproducens ΔldhA ΔpflD revealed a 45% improved product yield of 1.08 mol mol⁻¹. In addition, metabolic flux analysis unraveled the parallel in vivo activity of the oxidative and reductive branch of the TCA cycle in B. succiniciproducens, whereby the oxidative part mainly served for anabolism. The wild type re-directed surplus NADH via a cycle involving malic enzyme or via transhydrogenase, respectively, to supply NADPH for anabolism, because the fluxes through the oxidative PPP and isocitrate dehydrogenase, that also provide this cofactor, were not sufficient. This was not observed for the deletion mutants, B. succiniciproducens ΔpflD and ΔldhA ΔpflD, where PPP and isocitrate dehydrogenase flux alone matched with the reduced anabolic NADPH demand. The integration of the production performance into the theoretical flux space, computed by elementary flux mode analysis, revealed that B. succiniciproducens ΔldhA ΔpflD reached 62% of the theoretical maximum yield.
authors.affiliation: Institute of Biochemical Engineering, Technische Universität Braunschweig, Gaußstraße 17, Braunschweig, D-38106, Germany.
authors.forename: Judith
authors.initials: J
authors.lastname: Becker
authors.forename: Jasper
authors.initials: J
authors.lastname: Reinefeld
authors.forename: René
authors.initials: R
authors.lastname: Stellmacher
authors.forename: Rudolf
authors.initials: R
authors.lastname: Schäfer
authors.forename: Anna
authors.initials: A
authors.lastname: Lange
authors.forename: Hanna
authors.initials: H
authors.lastname: Meyer
authors.forename: Michael
authors.initials: M
authors.lastname: Lalk
authors.forename: Oskar
authors.initials: O
authors.lastname: Zelder
authors.forename: Gregory
authors.initials: G
authors.lastname: von Abendroth
authors.forename: Hartwig
authors.initials: H
authors.lastname: Schröder
authors.forename: Stefan
authors.initials: S
authors.lastname: Haefner
authors.forename: Christoph
authors.initials: C
authors.lastname: Wittmann
mesh_terms: D017353:Gene Deletion; D060847:Metabolic Engineering / Q000379:methods*; D064688:Metabolic Flux Analysis; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D015661:Pasteurellaceae / Q000235:genetics* / Q000378:metabolism*; D013386:Succinates / Q000378:metabolism*; D049490:Systems Biology / Q000379:methods*
chemical_list: D013386:Succinates
keywords: 13C metabolic flux analysis; OpenFlux; central carbon pathways; lactate dehydrogenase; pyruvate-formate lyase; redox metabolism; succinic acid