Unraveling the abilities of agaricus bisporus to degrade plant biomass throughout its life cycle

The common edible mushroom Agaricus bisporus is a basidiomycete that thrives on decaying plant material in the forests and grasslands of North America and Europe. It is adapted to forest litter and contributes to global carbon recycling, degrading cellulose, hemicellulose and lignin in plant biomass to oligomers and monomers. A. bisporus is also an edible mushroom that is widely cultivated and economically important. But the process of growing A. bisporus in compost and utilization of this substrate is poorly understood. In this study, we performed a wide analysis of genes encoding plant biomass degrading enzymes using high throughput sequencing (RNA-Seq) and lignocellulolytic enzymes secretion by A. bisporus grown in compost under commercial conditions to understand the carbon nutritive needs of the fungus and its capabilities to degrade plant biomass. Clear correlations were observed between secreted extracellular polysaccharide degrading enzymes, the expression of the corresponding genes and the composition of compost, which is rich in plant material such as cellulose and hemicellulose. Differences in the expression of genes from different stages of development were detected between spawning, pinning and harvesting stages, suggesting that as soon as the monosaccharides that were released during composting are depleted, A. bisporus starts producing enzymes to degrade plant biomass components to satisfy its nutritive needs. Interestingly, our results also uncovered differences in gene expression and secreted proteins between two different harvesting flushes that might be corresponded to the loss in number of mushrooms during second harvesting flush.