Efficient conversion of hemicellulose into high-value product and electric power by enzyme-engineered bacterial...

As an abundant agricultural and forestry biomass resource, hemicelluloses are hard to be effectively degraded and utilized by microorganisms due to the constraints of membrane and metabolic regulations. Herein, we report a synthetic extracellular metabolic pathway with hemicellulose-degrading-enzymes controllably displayed on Escherichia coli surface as engineered bacterial consortia members for efficient utilization of xylan, the most abundant component in hemicellulose. Further, we develop a hemicellulose/O₂ microbial fuel cell (MFC) configuring of enzyme-engineered bacterial consortia based bioanode and bacterial-displayed laccase based biocathode. The optimized MFC exhibited an open-circuit voltage of 0.71 V and a maximum power density (P_max) of 174.33 ± 4.56 µW cm^-2. Meanwhile, 46.6% (w/w) α-ketoglutarate was produced in this hemicellulose fed-MFC. Besides, the MFC retained over 95% of the P_max during 6 days' operation. Therefore, this work establishes an effective and sustainable one-pot process for catalyzing renewable biomass into high-value products and electricity in an environmentally-friendly way.