Self-Sustaining Bioelectrochemical Cell from Fungal Degradation of Lignin-Rich Agrowaste

• Main Authors: Asiah Sukri, Raihan Othman, Firdaus Abd-Wahab, Noraini M. Noor
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Energies
• Subjects: microbial zinc/air cell; <i>Phanaerochaete chrysosporium</i>; white-rot fungus; membraneless MFC; lignin-rich agrowaste
• Online Access: https://www.mdpi.com/1996-1073/14/8/2098

The present work describes a self-sustaining bioelectrochemical system that adopts simple cell configurations and operates in uncontrolled ambient surroundings. The microbial fuel cell (MFC) was comprised of white-rot fungus of <i>Phanaerochaete chrysosporium</i> fed with oil palm empty fruit bunch (EFB) as the substrate. This fungal strain degrades lignin by producing ligninolytic enzymes such as laccase, which demonstrates a specific affinity for oxygen as its electron acceptor. By simply pairing zinc and the air electrode in a membraneless, single-chamber, 250-mL enclosure, electricity could be harvested. The microbial zinc/air cell is capable of sustaining a 1 mA discharge current continuously for 44 days (i.e., discharge capacity of 1056 mAh). The role of the metabolic activities of <i>P. chrysosporium</i> on EFB towards the MFC’s performance is supported by linear sweep voltammetry measurement and scanning electron microscopy observations. The ability of the MFC to sustain its discharge for a prolonged duration despite the fungal microbes not being attached to the air electrode is attributed to the formation of a network of filamentous hyphae under the submerged culture. Further, gradual lignin decomposition by fungal inocula ensures a continuous supply of laccase enzyme and radical oxidants to the MFC. These factors promote a self-sustaining MFC devoid of any control features.