초록
<P><B>Significance</B></P><P>Hydrogen (H<SUB>2</SUB>) has great potential to be used to power passenger vehicles. One solution to these problems is to distribute and store renewable carbohydrate instead, converting it to hydrogen as required. In this work more than 10 purified enzymes were combined into artificial enzymatic pathways and a high yield from both glucose and xylose to hydrogen was achieved. Also, gaseous hydrogen can be separated from aqueous substrates easily, greatly decreasing product separation costs, and avoid reconcentrating sugar solutions. This study describes high-yield enzymatic hydrogen production from biomass sugars and an engineered reaction rate increase achieved through the use of kinetic modeling. Distributed hydrogen production based on evenly distributed less-costly biomass could accelerate the implementation of the hydrogen economy.</P><P>The use of hydrogen (H<SUB>2</SUB>) as a fuel offers enhanced energy conversion efficiency and tremendous potential to decrease greenhouse gas emissions, but producing it in a distributed, carbon-neutral, low-cost manner requires new technologies. Herein we demonstrate the complete conversion of glucose and xylose from plant biomass to H<SUB>2</SUB> and CO<SUB>2</SUB> based on an in vitro synthetic enzymatic pathway. Glucose and xylose were simultaneously converted to H<SUB>2</SUB> with a yield of two H<SUB>2</SUB> per carbon, the maximum possible yield. Parameters of a nonlinear kinetic model were fitted with experimental data using a genetic algorithm, and a global sensitivity analysis was used to identify the enzymes that have the greatest impact on reaction rate and yield. After optimizing enzyme loadings using this model, volumetric H<SUB>2</SUB> productivity was increased 3-fold to 32 mmol H<SUB>2</SUB>⋅L<SUP>−1</SUP>⋅h<SUP>−1</SUP>. The productivity was further enhanced to 54 mmol H<SUB>2</SUB>⋅L<SUP>−1</SUP>⋅h<SUP>−1</SUP> by increasing reaction temperature, substrate, and enzyme concentrations—an increase of 67-fold compared with the initial studies using this method. The production of hydrogen from locally produced biomass is a promising means to achieve global green energy production.</P>