title: Metabolic networks to generate pyruvate, PEP and ATP from glycerol in Pseudomonas fluorescens.
abstract: Glycerol is a major by-product of the biodiesel industry. In this study we report on the metabolic networks involved in its transformation into pyruvate, phosphoenolpyruvate (PEP) and ATP. When the nutritionally-versatile Pseudomonas fluorescens was exposed to hydrogen peroxide (H2O2) in a mineral medium with glycerol as the sole carbon source, the microbe reconfigured its metabolism to generate adenosine triphosphate (ATP) primarily via substrate-level phosphorylation (SLP). This alternative ATP-producing stratagem resulted in the synthesis of copious amounts of PEP and pyruvate. The production of these metabolites was mediated via the enhanced activities of such enzymes as pyruvate carboxylase (PC) and phosphoenolpyruvate carboxylase (PEPC). The high energy PEP was subsequently converted into ATP with the aid of pyruvate phosphate dikinase (PPDK), phosphoenolpyruvate synthase (PEPS) and pyruvate kinase (PK) with the concomitant formation of pyruvate. The participation of the phospho-transfer enzymes like adenylate kinase (AK) and acetate kinase (ACK) ensured the efficiency of this O2-independent energy-generating machinery. The increased activity of glycerol dehydrogenase (GDH) in the stressed bacteria provided the necessary precursors to fuel this process. This H2O2-induced anaerobic life-style fortuitously evokes metabolic networks to an effective pathway that can be harnessed into the synthesis of ATP, PEP and pyruvate. The bioconversion of glycerol to pyruvate will offer interesting economic benefit.
authors.affiliation: Faculty of Science and Engineering, Laurentian University, Sudbury, ON P3E2C6, Canada.
authors.forename: Azhar
authors.initials: A
authors.lastname: Alhasawi
authors.affiliation: Faculty of Science and Engineering, Laurentian University, Sudbury, ON P3E2C6, Canada.
authors.forename: Sean C
authors.initials: SC
authors.lastname: Thomas
authors.affiliation: Faculty of Science and Engineering, Laurentian University, Sudbury, ON P3E2C6, Canada. Electronic address: vappanna@laurentian.ca.
authors.forename: Vasu D
authors.initials: VD
authors.lastname: Appanna
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D056804:Biofuels; D002952:Citric Acid Cycle; D045222:Electron Transport Chain Complex Proteins / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D053858:Metabolic Networks and Pathways / Q000187:drug effects; D018384:Oxidative Stress; D010728:Phosphoenolpyruvate / Q000378:metabolism*; D011551:Pseudomonas fluorescens / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D019289:Pyruvic Acid / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D056804:Biofuels; D045222:Electron Transport Chain Complex Proteins; D010728:Phosphoenolpyruvate; D019289:Pyruvic Acid; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D005990:Glycerol
keywords: ATP; Bioconversion; Biodiesel; Glycerol; Metabolic networks; PEP; Pyruvate