Lignocellulose degradation characteristics and mechanisms of raw and NaOH-pretreated wheat straw by Irpex lacteus QJ: multi-omics analysis
摘要
The recalcitrant structure of lignocellulose hinders the efficient valorization of wheat straw. White-rot fungi have been extensively studied for their ability to completely degrade lignocellulose, yet the specific mechanisms remain insufficiently elucidated. In this study, the white-rot fungus Irpex lacteus QJ was applied to the solid-state fermentation of raw wheat straw (IW group) and NaOH-pretreated wheat straw (IN group). The degradation efficiency and mechanisms were investigated using enzyme activity assays, structural analyses (scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction), and multi-omics approaches. The results demonstrated that I. lacteus QJ effectively degraded wheat straw in both groups, and the IW group had significantly higher degradation rates of cellulose (56.21% vs. 41.90%), hemicellulose (57.30% vs. 42.94%) and lignin (54.90% vs. 42.23%), and significantly increased contents of crude protein (12.96% vs. 7.07%), thereby reducing the sugar concentration (33.18 mg/g vs. 9.63 mg/g) and lignocellulolytic enzyme activity. The results of the transcriptomic analysis revealed that the pathways enriched by the differentially expressed genes in the two groups were related to lignocellulose degradation. Key enzymes (including phenol hydroxylase, aldehyde dehydrogenase, and D-xylulose reductase) were identified by the protein‒protein interaction network. Metabolomic analysis revealed that the changes in most lignin-related metabolites were consistent between the two groups, and the levels of common metabolites such as methyl cinnamate and 4-acetamidobenzoic acid were strongly positively correlated with the lignocellulose degradation efficiency. In conclusion, this study systematically assessed the lignocellulose degradation performance of I. lacteus QJ and clarified its degradation mechanisms via multi-omics analyses, providing a theoretical reference for the fungus-mediated bioconversion of lignocellulosic biomass.
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