Biorefinery of non-food lignocellulosic plant biomass to be valorized as biofuels, biochemicals and biomaterials is considered as a sustainable alternative for fossil resource-based production. In biorefinery, a key step is enzymatic degradation of plant cell wall polysaccharides into (fermentable) monomers, which is driven by (hemi-)cellulases and essential lytic polysaccharide monooxygenases (LPMOs). Although some LPMOs have already been incorporated into industry, only a limited number of LPMOs have been biochemically characterized. Therefore, this PhD thesis aimed to shed light on the mode-of-action, regioselectivity, substrate cleavage profiles and specificity of AA9 LPMOs from the fungi Myceliophthora thermophila C1 (MtLPMOs) and Neurospora crassa (NcLPMOs).
We developed a new method for analysis of LPMO-generated oligosaccharides. We discovered novel double oxidized cello-oligosaccharides, and identified (isomeric) oxidized xylogluco-oligosaccharides. We showed two distinct oxidative xyloglucan degradation profiles, which were correlated to active site segment configurations of AA9 LPMOs. Lastly, we discovered that AA16 oxidoreductases can boost AA9 MtLPMOs to oxidatively degrade cellulose.