An efficient fungi-biochar-based system for advancing sustainable management of combined pollution

Heavy metal (HM) contamination poses significant global environmental threats, impacting ecosystems, public health, and sustainable development. Fungi, as eco-friendly alternatives to chemical treatments, have the potential to reduce HM bioavailability in contaminated soils while promoting plant growth. However, current fungal remediation methods face limitations in efficiency, long-term effectiveness, and the ability to address combined contamination, particularly with naturally occurring strains. Herein, we developed a Trichoderma reesei-Laccase (LAC)-Biochar coupling system (TLBS), based on the structural and electrostatic analyses of LAC's metal-chelated active site (T1 Cu), for the sustainable remediation of combined pollutants, including HMs. In the TLBS, genetically engineered T. reesei produces a mutated LAC with enhanced binding capability for HMs (Ni and Cd). The TLBS enables high-efficiency remediation through three steps. First, lignin-derived biochar serves as both a supportive carrier and an inducer, initiating LAC expression. Second, natural mediators are released due to the interaction between biochar and T. reesei, and LAC is activated by environmental HMs and natural mediators. Finally, TLBS achieved significant reductions in the available concentrations of Ni (93.63%) and Cd (89.68%) and efficiently remediated multiple organic pollutants (71.41-96.79%), including antibiotics and pesticides. Furthermore, the synergistic interaction among TLBS components ensures long-term remediation effects in environments rich in agricultural biomass, making it ideal for eco-friendly farming practices. This in situ amendment strategy, utilizing only green, biodegradable lignocellulosic wastes and environmentally friendly fungi, offers new pathways for the sustainable management of combined contamination and the improvement of human health.