Future transportation fuels might mainly consist of hydrogen for most vehicles, electricity for short-distance vehicles, and high-energy density liquid biofuels for jet planes. Therefore, it would be important to efficiently produce high-energy density liquid jet fuel (e.g., hydrocarbons, fatty acid esters or butanol) suitable for jet planes from less costly biomass sugars, because energy application usually decides its production.  Cell-free synthetic pathway biotransformation (SyPaB) is the in vitro assembly of a number of enzymes and coenzymes for implementation of complicated biochemical reactions that a single enzyme cannot do.  We demonstrate high-yield generation of NAD(P)H from a renewable biomass sugar � cellobiose through an in vitro synthetic enzymatic pathway consisting of 12 purified enzymes and coenzymes.  When the NAD(P)H generation system was coupled with its consumption reaction mediated by xylose reductase, the NADPH yield was as high as 11.4 mol NADPH per cellobiose (i.e., 95% of theoretical yield � 12 NADPH per glucose unit) in a batch reaction.  Consolidation of endothermic reactions and exothermic reactions in one pot results in a very high energy-retaining efficiency of 99.6% from xylose and cellobiose to xylitol.   The combination of this high-yield and projected low-cost biohydrogenation and aqueous phase reforming may be important for the production of sulfur-free liquid jet fuel in the future.

Biohydrogenation from biomass sugar mediated by in vitro synthetic enzymatic pathways

241st National Meeting (2011)

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