title: Engineering Escherichia coli for Microbial Production of Butanone.
abstract: To expand the chemical and molecular diversity of biotransformation using whole-cell biocatalysts, we genetically engineered a pathway in Escherichia coli for heterologous production of butanone, an important commodity ketone. First, a 1-propanol-producing E. coli host strain with its sleeping beauty mutase (Sbm) operon being activated was used to increase the pool of propionyl-coenzyme A (propionyl-CoA). Subsequently, molecular heterofusion of propionyl-CoA and acetyl-CoA was conducted to yield 3-ketovaleryl-CoA via a CoA-dependent elongation pathway. Lastly, 3-ketovaleryl-CoA was channeled into the clostridial acetone formation pathway for thioester hydrolysis and subsequent decarboxylation to form butanone. Biochemical, genetic, and metabolic factors affecting relative levels of ketogenesis, acidogenesis, and alcohol genesis under selected fermentative culture conditions were investigated. Using the engineered E. coli strain for batch cultivation with 30 g liter(-1)glycerol as the carbon source, we achieved coproduction of 1.3 g liter(-1)butanone and 2.9 g liter(-1)acetone. The results suggest that approximately 42% of spent glycerol was utilized for ketone biosynthesis, and thus they demonstrate potential industrial applicability of this microbial platform.
authors.affiliation: Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Kajan
authors.initials: K
authors.lastname: Srirangan
authors.affiliation: Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Xuejia
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Lamees
authors.initials: L
authors.lastname: Akawi
authors.affiliation: Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Mark
authors.initials: M
authors.lastname: Bruder
authors.affiliation: Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Murray
authors.initials: M
authors.lastname: Moo-Young
authors.affiliation: Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada cpchou@uwaterloo.ca.
authors.forename: C Perry
authors.initials: CP
authors.lastname: Chou
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods; D019149:Bioreactors; D053898:Biosynthetic Pathways; D002074:Butanones / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D005285:Fermentation; D005818:Genetic Engineering / Q000379:methods; D060847:Metabolic Engineering / Q000379:methods; D009876:Operon
chemical_list: D002074:Butanones