title: Temperature-dependent acetoin production by Pyrococcus furiosus is catalyzed by a biosynthetic acetolactate synthase and its deletion improves ethanol production.
abstract: The hyperthermophilic archaeon, Pyrococcus furiosus, grows optimally near 100°C by fermenting sugars to acetate, carbon dioxide and molecular hydrogen as the major end products. The organism has recently been exploited to produce biofuels using a temperature-dependent metabolic switch using genes from microorganisms that grow near 70°C. However, little is known about its metabolism at the lower temperatures. We show here that P. furiosus produces acetoin (3-hydroxybutanone) as a major product at temperatures below 80°C. A novel type of acetolactate synthase (ALS), which is involved in branched-chain amino acid biosynthesis, is responsible and deletion of the als gene abolishes acetoin production. Accordingly, deletion of als in a strain of P. furiosus containing a novel pathway for ethanol production significantly improved the yield of ethanol. These results also demonstrate that P. furiosus is a potential platform for the biological production of acetoin at temperatures in the 70-80°C range.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA.
authors.forename: Diep M N
authors.initials: DMN
authors.lastname: Nguyen
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA.
authors.forename: Gina L
authors.initials: GL
authors.lastname: Lipscomb
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA.
authors.forename: Gerrit J
authors.initials: GJ
authors.lastname: Schut
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Vaccaro
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA.
authors.forename: Mirko
authors.initials: M
authors.lastname: Basen
authors.affiliation: Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695-7905, USA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Kelly
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA. Electronic address: adams@bmb.uga.edu.
authors.forename: Michael W W
authors.initials: MWW
authors.lastname: Adams
mesh_terms: D000093:Acetoin / Q000378:metabolism*; D000095:Acetolactate Synthase / Q000096:biosynthesis* / Q000235:genetics; D002384:Catalysis; D000431:Ethanol / Q000302:isolation & purification / Q000378:metabolism*; D017353:Gene Deletion; D024861:Genetic Enhancement / Q000379:methods*; D060847:Metabolic Engineering / Q000379:methods*; D053858:Metabolic Networks and Pathways / Q000502:physiology; D020027:Pyrococcus furiosus / Q000235:genetics / Q000378:metabolism*; D013696:Temperature
chemical_list: D000431:Ethanol; D000093:Acetoin; D000095:Acetolactate Synthase
keywords: Acetoin; Acetolactate synthase; Archaea; Ethanol; Genetic engineering; Hyperthermophile