Quorum sensing autoinducers enhance biofilm formation and power production in a hypersaline microbial fuel cell

Intensive hydraulic fracturing of shale oil and gas reservoirs and other industrial activities can produce large volumes of high-organic-strength and high-salinity wastewaters that are difficult to treat by conventional technologies. Microbial fuel cells (MFC) can treat high-strength wastewater while generating electricity. We enhanced anodic biofilm formation by the extremophile Halanaerobium praevalens, a prevalent species in saline oil and gas reservoirs, in a hypersaline MFC (100 g/L NaCl), by promoting quorum sensing (QS) through addition of exogenous QS signals (i.e., Pseudomonas aeruginosa QS signal (PQS) and 4-hydroxy-1-methyl-2-quinolone (quinolone)). A 95% increase in biofilm mass was observed with the addition of 100 nM quinolone, yielding a sustained 30% increase in generated power density. Enhanced bacterial attachment to the anode's surface was corroborated by confocal microscopy. Overall, QS stimulation through the addition of trace levels of such autoinducers might be a feasible approach to enhance MFC performance under high-salinity conditions.