title: In vitro metabolic engineering of bioelectricity generation by the complete oxidation of glucose.
abstract: The direct generation of electricity from the most abundant renewable sugar, glucose, is an appealing alternative to the production of liquid biofuels and biohydrogen. However, enzyme-catalyzed bioelectricity generation from glucose suffers from low yields due to the incomplete oxidation of the six-carbon compound glucose via one or few enzymes. Here, we demonstrate a synthetic ATP- and CoA-free 12-enzyme pathway to implement the complete oxidation of glucose in vitro. This pathway is comprised of glucose phosphorylation via polyphosphate glucokinase, NADH generation catalyzed by glucose 6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH), electron transfer from NADH to the anode, and glucose 6-phosphate regeneration via the non-oxidative pentose phosphate pathway and gluconeogenesis. The faraday efficiency from glucose to electrons via this pathway was as high as 98.8%, suggesting the generation of nearly 24 electrons per molecule of glucose. The generated current density was greatly increased from 2.8 to 6.9mAcm-2by replacing a low-activity G6PDH with a high-activity G6PDH and introducing a new enzyme, 6-phosphogluconolactonase, between G6PDH and 6PGDH. These results suggest the great potential of high-yield bioelectricity generation through in vitro metabolic engineering.
authors.affiliation: Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin 300308, China; Cell-Free Bioinnovations Inc., 1800 Kraft Drive, Suite 222, Blacksburg, VA 24060, USA.
authors.forename: Zhiguang
authors.initials: Z
authors.lastname: Zhu
authors.affiliation: Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin Airport Economic Area, Tianjin 300308, China; Cell-Free Bioinnovations Inc., 1800 Kraft Drive, Suite 222, Blacksburg, VA 24060, USA; Biological Systems Engineering Department, Virginia Tech, 304 Seitz Hall, Blacksburg, VA 24061, USA. Electronic address: zhang_yh@tib.cas.cn.
authors.forename: Y-H Percival
authors.initials: YP
authors.lastname: Zhang
mesh_terms: D001674:Bioelectric Energy Sources / Q000382:microbiology*; D053898:Biosynthetic Pathways / Q000235:genetics*; D004560:Electricity; D004566:Electrodes / Q000382:microbiology*; D004735:Energy Transfer / Q000502:physiology; D004867:Equipment Design; D019544:Equipment Failure Analysis; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D060847:Metabolic Engineering / Q000379:methods*; D053858:Metabolic Networks and Pathways / Q000235:genetics; D010084:Oxidation-Reduction; D010427:Pentose Phosphate Pathway / Q000502:physiology
chemical_list: D029968:Escherichia coli Proteins; D005947:Glucose
keywords: Bioelectricity generation; Complete oxidation; Enzymatic fuel cell; In vitro metabolic engineering; Synthetic enzymatic pathway