Engineering synthetic microbial consortium for efficient conversion of lactate from glucose and xylose to generate electricity

Microbial fuel cell (MFC) is a sustainable electrochemical bioreactor that enables biomass harvesting to produce energy. Shewanella oneidensis, one of the widely used exoelectrogens in MFCs, can only utilize a limited spectrum of carbon sources. To enable the use of abundant carbon sources in MFCs, a lactate-mediated Saccharomyces cerevisiae and S. oneidensis microbial consortium was constructed to utilize 2 g/L xylose or 1 g/L glucose-xylose in generating electricity. The designed system achieved a constant supply of lactate to S. oneidensis, in which the lactate concentration was maintained at 0-0.1 g/L. Meanwhile, the output current promoted the metabolic rate of the carbon sources as well. Finally, the flavin biosynthesis pathway was incorporated into S. oneidensis to enhance the power production of the consortium, and the maximum output power density of 238.7 +/- 14.5 mW/m(2) was reached. This high-performance power generation could be attributed to the 'division-of-labor' between the fermenter and exoelectrogen based on the programmed cooperation and mutualistic interactions among individuals.