Characterizing the Activity of Electrochemically Active Bacteria in Microbial Fuel Cells in the Presence of Toxic Cyanobacteria

The frequent occurrence of cyanobacterial harmful algal blooms (cHABs) poses serious threats to freshwater habitats and drinking water resources due to the impairment of the ecosystem and the production of Microcystis Aeruginosa, a highly toxic strain of cyanobacteria. Microcystis Aeruginosa produces a cyanotoxin, MC-LR, that is hard to destruct and causes serious damage to the liver if ingested. This research aims to treat cHABs by utilizing the natural metabolic processes of electrochemically active bacteria (EAB), a group of bacteria that are naturally present in aquatic ecosystems. EABs are capable of oxidizing organic matter, including algal biomass, through biocatalytic reactions, releasing electrons in the process. A microbial fuel cell (MFC) can harvest the electricity produced from EAB in an anaerobic anode chamber while exchanging protons with an aerobic cathode chamber. By using cHAB infected lake water as a substrate, an MFC can treat lake water while generating electricity. In this work, we have set up the system to test the electrical activity of various EAB strains from Central Park Pond water by carrying out cyclic voltammetry tests in a dual-chamber MFC, with each isolated strain at a time. The most active strains were identified by the intensity of their reduction and oxidation peaks in a current vs. voltage plot (CV plot). Longer tests will be carried out with Microcystis Aeruginosa present in the media as substrate for EAB. The efficacy of EAB in treating cyanobacteria will be identified by the concentration of intracellular and extracellular MC-LR toxin. In this work, we also tested multiple methods to isolate intracellular toxin from cyanobacteria and to accurately identify MC-LR levels in samples pre and post treatment including plate essay, Western blot, and HPLC.