Fungal bioaugmentation enhanced herbicide removal via soil microbial fuel cell: Taking Myrothecium verrucaria and...

Microbial fuel cell (MFC), which produces electricity while removing pollutants, is a green approach of ecological restoration. Whether fungal bioaugmentation could enhance the herbicide removal in MFC has not been fully investigated. This study aims to construct the fungal-augmented MFC device, compare the effects of different types of remediation against soil haloxyfop-P, and explore the mechanisms of xeno-fungusphere MFC in alleviating organic pollution. The Myrothecium verrucaria addition achieved the current density of 15.27 μA/cm² and power density (PD) of 1.174 μW/cm², which were much higher than those with indigenous microbes and MFC alone. On day 60, the haloxyfop removal efficiency of 93.7 % was achieved with the M. verrucaria bioaugmentation, and double herbicide further increased the removal efficiency to 97.9 %, along with PD of 9.3 μW/cm². The M. verrucaria addition significantly changed the correlation pattern between bacterial genera, as well as between dominant genera and herbicide degradation, electrogenesis, edaphic factors and functional abundance. Facing herbicide challenge, the biogeochemical processes of C/N/Fe/Mn/S were reorganized in MFC microbiota, which were also profoundly impacted by bioelectric field and xeno-fungusphere. The MFC degradation of haloxyfop-P followed the second-order kinetics; the fungal addition reduced the gap between the highest occupied molecular orbitals and lowest unoccupied molecular orbitals of herbicide molecules, and reduced the energy barrier for the herbicide transformation. Compared with MFC alone, xeno-fungusphere MFC had a better effect, which can remediate the soil without additional power supply, making it a cost-effective self-sustaining remediation strategy.