Hybrid nanocatalyst microbial pretreatment of lignocellulosic biomass: A synergistic approach for accelerated biogas production

Lignocellulosic biomass represents an abundant renewable resource for biogas production, yet its intrinsic recalcitrance severely limits anaerobic digestion (AD) efficiency. Lignin encapsulation, cellulose crystallinity, and slow hydrolysis kinetics restrict methane recovery to 40–70% of theoretical potential. This review examines a novel hybrid approach combining white-rot fungi pretreatment with magnetite nanoparticle (MNP) supplementation to overcome these limitations. This review article proposes a three-mechanism synergy hypothesis: (i) bioavailable Fe³ ⁺ from magnetite stimulates fungal growth and lignin-modifying enzyme (LME) synthesis; (ii) nanoparticle surfaces promote enzyme immobilization and stabilization; and (iii) redox-active magnetite facilitates electron transfer during lignin oxidation and downstream direct interspecies electron transfer (DIET)-mediated methanogenesis. Emerging evidence from wheat straw, corn stover, and aquatic biomass systems supports these synergistic effects. However, critical research gaps remain: no peer-reviewed study has validated a fully integrated hybrid system combining WRF pretreatment with simultaneous MNP supplementation across both pretreatment and AD stages. Multi-omics mechanistic elucidation, nanoparticle optimization, pilot-scale demonstration, techno-economic analysis, and comprehensive life-cycle assessments are urgently needed. If these gaps are addressed, this approach has the potential to become a transformative platform technology for advanced biorefineries, contributing to climate change mitigation and the circular bioeconomy.