Engineering enables xylose-fed microbial fuel cell.

BACKGROUND

The microbial fuel cell (MFC) is a green and sustainable technology for electricity energy harvest from biomass, in which exoelectrogens use metabolism and extracellular electron transfer pathways for the conversion of chemical energy into electricity. However, MR-1, one of the most well-known exoelectrogens, could not use xylose (a key pentose derived from hydrolysis of lignocellulosic biomass) for cell growth and power generation, which limited greatly its practical applications.

RESULTS

Herein, to enable to directly utilize xylose as the sole carbon source for bioelectricity production in MFCs, we used synthetic biology strategies to successfully construct four genetically engineered (namely XE, GE, XS, and GS) by assembling one of the xylose transporters (from and ) with one of intracellular xylose metabolic pathways (the isomerase pathway from and the oxidoreductase pathway from ), respectively. We found that among these engineered strains, the strain GS (i.e. harbouring gene encoding the xylose facilitator from , and , , and genes encoding the xylose oxidoreductase pathway from ) was able to generate the highest power density, enabling a maximum electricity power density of 2.1 ± 0.1 mW/m.

CONCLUSION

To the best of our knowledge, this was the first report on the rationally designed that could use xylose as the sole carbon source and electron donor to produce electricity. The synthetic biology strategies developed in this study could be further extended to rationally engineer other exoelectrogens for lignocellulosic biomass utilization to generate electricity power.