title: Increased NADPH availability in Escherichia coli: improvement of the product per glucose ratio in reductive whole-cell biotransformation.
abstract: A basic requirement for the efficiency of reductive whole-cell biotransformations is the reducing capacity of the host. Here, the pentose phosphate pathway (PPP) was applied for NADPH regeneration with glucose as the electron-donating co-substrate using Escherichia coli as host. Reduction of the prochiral β-keto ester methyl acetoacetate to the chiral hydroxy ester (R)-methyl 3-hydroxybutyrate (MHB) served as a model reaction, catalyzed by an R-specific alcohol dehydrogenase. The main focus was maximization of the reduced product per glucose yield of this pathway-coupled cofactor regeneration with resting cells. With a strain lacking the phosphoglucose isomerase, the yield of the reference strain was increased from 2.44 to 3.78 mol MHB/mol glucose. Even higher yields were obtained with strains lacking either phosphofructokinase I (4.79 mol MHB/mol glucose) or phosphofructokinase I and II (5.46 mol MHB/mol glucose). These results persuasively demonstrate the potential of NADPH generation by the PPP in whole-cell biotransformations.
authors.affiliation: Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, 52425, Jülich, Germany.
authors.forename: Solvej
authors.initials: S
authors.lastname: Siedler
authors.forename: Stephanie
authors.initials: S
authors.lastname: Bringer
authors.forename: Michael
authors.initials: M
authors.lastname: Bott
mesh_terms: D001711:Biotransformation; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D009249:NADP / Q000378:metabolism*; D010427:Pentose Phosphate Pathway
chemical_list: D029968:Escherichia coli Proteins; D009249:NADP; D005947:Glucose