Preliminary study of electricity generation and sulfate removal performance in a novel air-cathode microbial fuel cell (AC-MFC) using laccase-producing yeast as a biocatalyst

Abstract

Fungi produce various types of extracellular enzymes, including the copper-containing oxidative enzyme laccase. This enzyme uses gaseous oxygen (O2) as an electron acceptor to catalyze oxidation of phenolic compounds, and therefore it can act as a cathode biocatalyst in a microbial fuel cell (MFC). In this study, a new model of the air-cathode microbial fuel cell (AC-MFC) was constructed. For its design, the laccase-producing yeast Galactomyces reessii cultured in potato dextrose agar was grown in the cathode chamber, and an anaerobic microbial community was maintained in the anode chamber in order to carry out sulfate removal and, simultaneously, generate electricity. Results showed that the cathode with G. reessii outperformed the cathode with sterile gel (negative control), yielding the maximum open circuit voltage of 550.65±14.92 mV, the maximum power density of 0.35±0.01 mW/m3, the maximum current density of 225.69±17.25 mA/m3 and sulfate removal of 73.29±1.31%. This study demonstrated the feasibility of using a yeast culture for continuous laccase production in the cathode chamber of the AC-MFC in order to improve their electricity generation and sulfate removal.