Hypersaline microbial fuel cell equipped with an oxygen-reducing microbial cathode

Microbial anodes and oxygen reducing microbial cathodes were designed separately under constant polarization at + 0.1 V/SCE in a hypersaline medium (NaCl 45 g/L). They were then associated to design two-compartment microbial fuel cells (MFCs). These MFCs produced up to 209 +/- 24 mW m- 2 during a week. This was the first demonstration that hypersaline MFCs equipped with microbial cathodes can produce power density at this level. Desulfuromonas sp. were confirmed to be key species of the anodes. The efficiency of the cathodes was linked to the development of a redox system centred at + 0.2 V/SCE and to the presence of Gammaproteobacteria (Alteromonadales and Oceanospirillales), especially an unclassified order phylogenetically linked to the genus Thioalobacter. Comparing the different performance of the four MFCs with the population analyses suggested that polarization at + 0.1 V/SCE should be maintained longer to promote the growth of Thioalobacter on the cathode and thus increase the MFC performance.

Automated summary

Microbial anodes and oxygen reducing microbial cathodes were designed separately and then combined to form two-compartment microbial fuel cells. The MFCs produced significant power density in a hypersaline medium, with Desulfuromonas sp. identified as key species of the anodes. The efficiency of the cathodes was linked to the development of a redox system centered at a certain voltage and the presence of specific phylogenetically linked bacteria. Comparing different MFCs' performances suggested that maintaining longer polarization at a certain voltage could promote growth of specific bacteria on the cathode and enhance MFC performance.