FTIR and XPS analysis of the changes in bamboo chemical structure decayed by white-rot and brown-rot fungi

In order to investigate different types of decay mechanisms in bamboo (Phyllostachys edulis), the chemical structure and microstructure of bamboo samples decayed by P. chrysosporium (White-rot) and G. trabeum (Brown-rot) for 12 weeks were studied. The analysis methods include fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron spectroscopy (SEM). By using the SEM method, it was found that attacks to parenchyma cells and places near the inner skin of bamboo were the most frequent and the vessels were the primary paths for the spread of mycelium in the bamboo. FTIR and XPS results showed that the crystallinity (I1425/I896) of bamboo decreased after being decayed by these two fungi and the crystalline cellulose in bamboo was degraded. The white-rot P. chrysosporium had stronger degradability on lignin compared to hemicellulose and cellulose in bamboo. And the brown-rot G. trabeum had preferential degradability on hemicellulose fraction over cellulose and lignin. Oxidation and hydrolysis surface reactions occurred during the process of decay, but the reaction rates for cellulose and lignin were different.