Temperature-Dependent Conversion of Wheat Straw by Ganoderma lucidum: A Chemical and Multi-Omics Analysis

Temperature critically regulates fungal lignocellulose degradation, but the mechanisms underlying straw conversion by Ganoderma lucidum for ruminant feed remain unclear. This study investigated biochemical and molecular responses of G. lucidum during solid-state fermentation of wheat straw at 20, 27, and 34 °C over 0, 2, 4, and 6 weeks using chemical, transcriptomic and metabolomic analyses. At week 6, lignin degradation reached 63.6% at 27 °C and 34 °C, exceeding 27.0% at 20 °C. Similarly, hemicellulose degradation reached 60% at 27 °C and 34 °C, exceeding 33.2% at 20 °C. In contrast, cellulose degradation showed more consistent temperature dependence, with 46.1% at 34 °C and 21.6% at 20 °C. Transcriptomics revealed temperature-dependent activation of carbohydrate-active enzymes and lignin-modifying genes, including up-regulated laccase genes, as well as temperature-specific induction of xylitol dehydrogenase at 27 °C and barwin-like endoglucanase at 34 °C. Metabolite profiles showed partial convergence between extended low-temperature and short-term high-temperature fermentation. Multi-omics integration identified a conserved negative correlation between phenylpropanoid/lignan and lipid/organic acid metabolites, alongside temperature-dependent remodeling of gene and metabolite networks. This study reveals chemical, transcriptomic, and metabolomic changes during solid-state fermentation of wheat straw by G. lucidum, providing mechanistic insights into temperature-regulated fungal biomass conversion.