The secretome of Agaricus bisporus: Temporal dynamics of plant polysaccharides and lignin degradation

Despite substantial lignocellulose conversion during mycelial growth, previous transcriptome and proteome studies have not yet revealed how secretomes from the edible mushroom Agaricus bisporus develop and whether they modify lignin models in vitro. To clarify these aspects, A. bisporus secretomes collected throughout a 15-day industrial substrate production and from axenic lab-cultures were subjected to proteomics, and tested on polysaccharides and lignin models. Secretomes (day 6-15) comprised A. bisporus endo-acting and substituent-removing glycoside hydrolases, whereas beta-xylosidase and glucosidase activities gradually decreased. Laccases appeared from day 6 onwards. From day 10 onwards, many oxidoreductases were found, with numerous multicopper oxidases (MCO), aryl alcohol oxidases (AAO), glyoxal oxidases (GLOX), a manganese peroxidase (MnP), and unspecific peroxygenases (UPO). Secretomes modified dimeric lignin models, thereby catalyzing syringylglycerol-beta-guaiacyl ether (SBG) cleavage, guaiacylglycerol-beta-guaiacyl ether (GBG) polymerization, and non-phenolic veratrylglycerol-beta-guaiacyl ether (VBG) oxidation. We explored A. bisporus secretomes and insights obtained can help to better understand biomass valorization.

Automated summary

Proteomic analysis revealed that the secretomes of Agaricus bisporus showed significant changes during its 15-day growth in the substrate, with a decrease in β-xylosidase and glucosidase activities and an increase in laccase and oxidoreductase activities. These secretomes were also able to modify lignin models, promoting biomass valorization.