A sustainable hydrochar-hydroxyapatite nano-bio interface enabling accelerated fungal lignocellulose deconstruction.

Abstract

The recalcitrance of lignocellulosic biomass (LB) remains a major barrier to sustainable biorefinery development, as conventional thermochemical pretreatment requires harsh conditions, high energy input, and generates inhibitory by-products. Here, we report a sustainable nano-enabled fungal pretreatment strategy based on a hydrochar-hydroxyapatite (HBC-HA) composite that significantly enhances wild-type Aspergillus fumigatus AF01-mediated lignocellulose deconstruction. The integrated AF01/HBC-HA system achieved 39.8% lignin degradation within 7 days, representing a 1.85-fold improvement over the control, while markedly enhancing lignocellulolytic enzyme activities, including cellulase (4.6-fold), β-glucosidase (3.5-fold), xylanase (5.1-fold), and laccase (4.4-fold). Apparent kinetic analysis revealed increased catalytic efficiency (3.5-4.6-fold increase in Vmax) and improved substrate affinity (1.3-1.8-fold reduction in Km). Hydroxyapatite may contribute to extracellular enzyme stabilization via hydrogen bonding and electrostatic interactions, while hydrochar may reduce lignocellulose-derived inhibitor stress and provide a favorable microenvironment. Subsequent enzymatic hydrolysis with Cellic® CTec2 confirmed improved substrate accessibility, with reducing sugar release increasing 2.3-fold compared with AF01 pretreatment alone and 9.2-fold relative to untreated straw. Multi-omics analysis further suggests a reinforcing feedback loop involving enhanced depolymerization, reduced inhibitory stress, and upregulated metabolic pathways associated with lignocellulose degradation and detoxification. This work suggests that the integration of HBC-HA with fungal systems can be a promising alternative to conventional pretreatment methods.

Abstract as supplied by the indexing source. © the authors / publisher.