4 years ago

TSynthetic Klebsiella pneumoniae-Shewanella oneidensis consortium enables glyc-erol-fed high-performance microbial fuel cells

Feng Li, Liming Sun, Yuanxiu Li, Changji Yin, Xuewu Guo, Hao Song
Microbial fuel cell (MFC) is an eco-friendly bio-electrochemical system that uses mi-croorganism as biocatalyst to convert biomass into electricity. Glycerol, as a waste in the biodiesel refinery processes, is an appealing substrate for MFC. Nevertheless, glycerol cannot be utilized as carbon source by well-known exoelectrogens such as Shewanella oneidensis. Herein, to generate electricity by rapidly harnessing glycerol, we rationally constructed a Klebsiella pneumoniae-Shewanella oneidensis microbial consortium to efficiently harvest electricity from glycerol, in which K. pneumoniae converted glycerol into lactate, fed to S. oneidensis as carbon source and electron do-nor. To improve electricity output, we systematically engineered the consortium in terms of carbon flux distribution and efficiency of extracellular electron transfer (EET). To direct more carbon flux to lactate biosynthesis in K. pneumoniae, we elimi-nated the ethanol pathway by knocking out the alcohol dehydrogenase gene (adhE), and enhanced lactate biosynthesis by heterologously expressing a lactate dehydrogen-ase gene (ldhD) from Lactobacillus bulgaricus and a lactate transporter gene (lldP) from Escherichia coli. To facilitate EET between S. oneidensis and anode surfaces, a biosynthetic flavins pathway from Bacillus subtilis was introduced into S. oneidensis. We further optimized the glycerol concentration, thus S. oneidensis could be continu-ously fed with lactate synthesized from K. pneumoniae at a constant rate. Our glycer-ol-fed MFC generated a maximum power density of 19.9 mW/m2, significantly higher than that of the wild-type consortium. This work suggested that engineering microbial consortia is an efficient strategy to expand the spectrum of usable carbon sources and promote electricity power production in MFCs.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/biot.201700491

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