title: Biochemical, genetic, and metabolic engineering strategies to enhance coproduction of 1-propanol and ethanol in engineered Escherichia coli.
abstract: We recently reported the heterologous production of 1-propanol in Escherichia coli via extended dissimilation of succinate under anaerobic conditions through expression of the endogenous sleeping beauty mutase (Sbm) operon. In the present work, we demonstrate high-level coproduction of 1-propanol and ethanol by developing novel engineered E. coli strains with effective cultivation strategies. Various biochemical, genetic, metabolic, and physiological factors affecting relative levels of acidogenesis and solventogenesis during anaerobic fermentation were investigated. In particular, CPC-PrOH3, a plasmid-free propanogenic E. coli strain derived by activating the Sbm operon on the genome, showed high levels of solventogenesis accounting for up to 85 % of dissimilated carbon. Anaerobic fed-batch cultivation of CPC-PrOH3 with glycerol as the major carbon source produced high titers of nearly 7 g/L 1-propanol and 31 g/L ethanol, implying its potential industrial applicability. The activated Sbm pathway served as an ancillary channel for consuming reducing equivalents upon anaerobic dissimilation of glycerol, resulting in an enhanced glycerol dissimilation and a major metabolic shift from acidogenesis to solventogenesis.
authors.affiliation: Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada, N2L 3G1.
authors.forename: Kajan
authors.initials: K
authors.lastname: Srirangan
authors.forename: Xuejia
authors.initials: X
authors.lastname: Liu
authors.forename: Adam
authors.initials: A
authors.lastname: Westbrook
authors.forename: Lamees
authors.initials: L
authors.lastname: Akawi
authors.forename: Michael E
authors.initials: ME
authors.lastname: Pyne
authors.forename: Murray
authors.initials: M
authors.lastname: Moo-Young
authors.forename: C Perry
authors.initials: CP
authors.lastname: Chou
mesh_terms: D000433:1-Propanol / Q000378:metabolism*; D000693:Anaerobiosis; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism*; D005990:Glycerol / Q000378:metabolism; D060847:Metabolic Engineering / Q000379:methods*; D053858:Metabolic Networks and Pathways / Q000235:genetics
chemical_list: D000431:Ethanol; D000433:1-Propanol; D005990:Glycerol