Exploring the brine pool in the Red Sea as a source of exoelectrogenic communities. Exploring exoelectrogens in the brine pool Red Sea

One of the challenges for using microbial electrochemical technologies (METs) with highly saline or thermophilic solutions is the lack of microbes capable of forming a biofilm and generating electrical current under these conditions. Three different locations at different depths of brine pools in the Red Sea were investigated as inocula sources for exoelectrogenic biofilms that could grow at 70oC in highly saline medium: Valdivia, Atlantis II, and Kebrit. Of these, only the inoculum from the Valdivia brine pool produced high and consistent current 6.8 ± 2.1 A/m2-anode (over 60 days) in microbial electrolysis cells (MECs) operated at a set anode potential of +0.2 V vs Ag/AgCl (+0.405 V vs. SHE), with 10 mM acetate as the electron donor. Analysis of the microbial communities with the Valdivia inoculum using 16S rRNA gene pyrosequencing showed at the genus level that sequences most similar to Bacteroides were the predominant microorganisms at the anode. These results show that microorganisms capable of producing electrical current are present in at least one of these extreme environments in the Red Sea. Enriching for efficient exoelectrogenic communities from extreme environments will provide new opportunities for niche-specific applications of METs.