Fungal specificity in degradation of Moso bamboo: White-rot versus brown-rot fungi

From the paper

Abstract

Moso bamboo (Phyllostachys edulis) is a cornerstone material in industrial processing, bamboo construction, and the manufacturing of bamboo products. However, its unique composition, particularly its high starch content, makes it highly susceptible to fungal decay, which leads to a significant loss of its mechanical properties. In this study, Moso bamboo samples were colonized by four prevalent decay fungi: the white-rot species Phanerochaete chrysosporium and Trametes versicolor, and the brown-rot species Gloeophyllum trabeum and Postia placenta. The objective was to investigate the time-dependent changes in the structure and chemical composition of the bamboo to elucidate their degradation mechanisms. The results indicated that after a 16-week incubation, the white-rot fungus Trametes versicolor caused the highest mass loss of 55.1 %, while Postia placenta caused only 19.8 %; the pH of the bamboo samples decreased over time, with samples inoculated with brown-rot fungi exhibiting a more acidic nature; the relative crystallinity values incubated in T. versicolor and Gloeophyllum trabeum are 59.72 % and 45.09 %, respectively. Structural analysis revealed that brown-rot showed different degradation patterns from white-rot fungi by showing preferential attack of vessels and fibers. The results of chemical composition analysis and X-ray photoelectron spectroscopy (XPS) further proved that brown-rot fungi primarily degrade cellulose and hemicellulose. In contrast, white-rot fungi preferential attack in the order of vessels, parenchyma, and then fibers. Chemical analysis and XPS confirmed that T. versicolor selectively degrades lignin, leading to the exposure of microfibrils in the cell walls, thereby leading to an increase in the crystallinity of bamboo. This study demonstrates the different decay pathways of white-rot and brown-rot fungi in Moso bamboo. These findings are vital for the sustainable use of bamboo and wood residues, improving the longevity of bamboo composites, and developing new bioremediation solutions for bamboo waste.