(609b) Engineering Microbial Consortia for Bioelectrocatalysis Processes

Bioelectrochemical systems hold great promises for diverse bioenergy and environmental applications, including microbial fuel cells (MFC) for green and sustainable bioelectricity production from wastewater and biomass, autonomous power sources for sensors and beacons by marine sediment MFCs, sea waters desalination by microbial desalination cells, hydrogen production by microbial electrolysis cells, and microbial electrosynthesis for CO₂ reduction and chemicals production.

However, exoelectrogens, such as Shewanella and Geobacter being widely studied in MFCs, could only use limited spectrum of carbon sources. To expand the carbon source range being used in MFCs, we herein rationally designed a few microbial consortia to broaden the carbon sources that could be used in MFCs and bioelectrochemical systems. Firstly, we constructed a glucose-fed fungus-bacteria microbial consortium including a fermenter (Saccharomyces cerevisiae) in which the ethanol pathway was knocked out and the lactic acid biosynthesis pathway was introduced into Shewanella cerevisiae, and an exoelectrogen (S. oneidensis MR-1). We optimized the co-culturing conditions of the microbial consortium to achieve an optimal coordination between carbon source metabolism of the fermenter and extracellular electron transfer of the exoelectrogen, such that lactate, the metabolic product of glucose by the recombinant S. cerevisiae, was continuously supplied to S. oneidensis in a constant level until glucose exhaustion. This metabolic coordination between the fermenter and the exoelectrogen enabled bioelectricity production in a glucose-fed MFC. Secondly, we used the design principle of ‘‘division-of-labor’’ to construct a three-species microbial consortium for power generation, consisting of recombinant Escherichia coli, Bacillus subtilis and Shewanella oneidensis. In this consortium, E. coli digested glucose to produce lactate as a carbon source, B. subtilis produced riboflavin as an electron shuttle, and S. oneidensis served as the exoelectrogen to generate electricity. The three species formed a cross-feeding microbial consortium, performing ‘‘better together’’ for power generation.

Our study provided new insights into the rational design of more efficient, stable, and robust synthetic microbial consortia applicable in bioenergy and environments.

References:
1. Yue Liu, Mingzhu Ding, Wei Ling, Yun Yang, Xiao Zhou, Bingzhi Li, Tao Chen, Yong Nie, Miaoxiao Wang, Boxuan Zeng, Xia Liwi, Hong Liu, Baode Sun, Heming Xu, Jiamei zhang, Yi Jiao, Yanan Hou, Hui Yang, Sijia Xiao, Qucheng Lin, Xinzi He, Wenjie Liao, Zeqi Jin, Yufei Xie, Bofeng Zhang, Tianyu Li, Xi Lu, Jiabei Li, Fan Zhang, Hao Song*, Yingjin Yuan*, “A three-species microbial consortium for power generation”, Energy & Environmental Science, DOI: 10.1039/C6EE03705D (in press, 2017)

2. Tong Lin, Xue Bai, Yun Yang, Jingyu Wang, Yidan Hu, Bingzhi Li, Ying-Jin Yuan, Hao Song*, “Synthetic Saccharomyces cerevisiae-Shewanella oneidensis consortium enables glucose-fed microbial fuel cell”, AIChE Journal, (in press, 2017)