Fungal degradation strategies during solid-state fermentation of cereal brans with white-rot fungi

Cereal brans are abundant agro-industrial residues rich in polysaccharides, phenolic acids, and proteins, making them promising substrates for biotechnological valorization. This study investigated the progressive modification of wheat and corn bran during solid-state fermentation by three white-rot fungi (Pleurotus ostreatus, Fomes fomentarius and Ganoderma lucidum) to elucidate how fungal degradation performance is influenced by substrate composition. Fourier Transform Infrared Spectroscopy (FTIR) and Two-Dimensional Nuclear Magnetic Resonance (2D-NMR) analysis revealed preferential hemicelluloses degradation in both brans, accompanied by substantial alterations in signals associated with phenolic compounds, particularly ferulates. Among the tested fungi, F. fomentarius achieved the greatest carbohydrate reduction in wheat bran (51% w/w) and P. ostreatus in corn bran (15% w/w). All species degraded phenolic acids in wheat bran, while corn bran exhibited an enrichment of ferulic acid (up to 38% w/w), indicating greater structural recalcitrance. Enzymatic profiling showed that wheat bran promoted higher xylanase and cellulase activities, whereas laccase activity was primarily species-dependent. Overall, these findings provide a systematic understanding of fungal mediated degradation pathways in cereal brans and highlight the critical role of substrate composition in shaping white-rot fungi strategies in lignocellulosic bioprocesses.