Production of renewable fuels and chemicals from biomass requires an efficient pretreatment technology, which further depends on better understanding of biodegradation process of such lignocellulosic biomass. The biodegradation of wheat straw by Phanerochaete chrysosporium was investigated in this study. The fungal secretomes and compositional, functional groups and structural changes of the fungal spent wheat straw lignin were determined. The result showed similar to 30% loss of total lignin within three weeks of biopretreatment by P. chrysosporium. Detailed structural analysis through two dimentional heteronuclear multiple quantum coherence nuclear magnatic resonance (2D HMQC NMR) of the pretreated lignin (acetylated) revealed low abundance of substructures D (dibenzo-dioxacin) and E (cinnamyl alcohol). Further, analysis of lignin by Fourier Transmission Infrared (FTIR) and Pyrolysis Gas Chromatography/Mass Spectrometry (Py-GC/MS) demonstrated the significant decrease of guaiacyl (G) units. The results support the previous findings in the biodegradation of wheat straw analyzed by C-13 cross polarization magic angle spinning (CPMAS). Revealing the characteristic behavior of P. chrysosporium mediated biomass degradation, the information presented in this paper offers new insights for understanding the biological lignin degradation of wheat straw by P. chrysosporium. (C) 2010 Elsevier Ltd. All rights reserved.