Screening White-Rot Fungi and Characterizing Lignocellulose Degradation by Ganoderma sp. from Chinese Distillers’ Grains

Abstract

Chinese distillers’ grains (CDGs) are a lignocellulose-rich agricultural byproduct with considerable bioconversion potential; however, their recalcitrant structure imposes a major bottleneck for efficient valorization. In this study, six white-rot fungal strains and two Trichoderma strains were isolated from wild macrofungi, among which Ganoderma sp. 2G1-6 exhibited the highest laccase activity, reaching 11.29 U/mL. Whole-genome sequencing revealed a 49.15 Mb genome containing 12,437 predicted proteins, including a substantial repertoire of 196 glycoside hydrolases and 113 auxiliary activity enzymes implicated in lignocellulose degradation. Solid-state fermentation of CDGs with Ganoderma sp. 2G1-6 produced high enzyme activities, including endoglucanase (13.3 ± 4.6 U/g), xylanase (538.8 ± 33.0 U/g), β-glucosidase (26,572 ± 2996 U/g), and laccase (231.2 ± 16.7 U/g). Concomitantly, the nutritional profile of CDGs was markedly improved after 30 days, with crude protein increasing by 28.51%, acid-soluble protein by 33.33%, and soluble dietary fiber by 159%. Complementary structural analyses (FTIR, SEM, XRD, and TGA) confirmed progressive disruption of the lignocellulosic matrix, selective delignification, and enhanced cellulose exposure. These findings establish Ganoderma sp. 2G1-6 as a promising microbial chassis for CDGs valorization and provide preliminary functional profiles of Ganoderma species for lignocellulose bioconversion.