Two-stage wood decay by Grifola frondosa.

In nature, only white-rot fungi can completely decompose wood biomass in the environmental carbon cycle. However, their degradation strategy is still unclear. Despite many studies on the lab-scale wood-decay process, investigations on the open-field process have been limited by their difficulty. Here, we aimed to elucidate the degradation strategy of white-rot fungi in nature by monitoring the chemical composition changes of logs exposed to the white-rot fungus, Grifola frondosa, over 4 y of cultivation using Fourier transform infrared spectroscopy. Grifola frondosa began to decompose lignin and deacetylate hemicellulose in the first 2 y and then degraded polysaccharides in the next 1 y. Finally, lignin decomposition recurred after the third year. Thus, our study revealed that G. frondosa decayed wood in a repetitive two-stage process: lignin and polysaccharide degradation. The switching cycle may promote efficient degradation.