Insights into the H2O2-Driven Lytic Polysaccharide Monooxygenase Activity on Efficient Cellulose Degradation in the White Rot Fungus Irpex lacteus

In contrast to O-2, H2O2 as thecosubstrate for lytic polysaccharide monooxygenases (LPMOs) exhibitsgreat advantages in industrial settings for cellulose degradation.However, H2O2-driven LPMO reactions from naturalmicroorganisms have not been fully explored and understood. Herein,secretome analysis unraveled the H2O2-drivenLPMO reaction in the efficient lignocellulose-degrading fungus Irpex lacteus, including LPMOs with different oxidativeregioselectivities and various H2O2-generatingoxidases. Biochemical characterization of H2O2-driven LPMO catalysis showed orders of magnitude improvement incatalytic efficiency compared to that of O-2-driven LPMOcatalysis for cellulose degradation. Significantly, H2O2 tolerance of LPMO catalysis in I. lacteus was an order of magnitude higher than that in other filamentousfungi. In addition, natural reductants, gallic acid, in particular,presented in lignocellulosic biomass could sufficiently maintain LPMOcatalytic reactions. Moreover, the H2O2-drivenLPMO catalysis exhibited synergy with canonical endoglucanases forefficient cellulose degradation. Taken together, these findings demonstratethe great application potential of the H2O2-drivenLPMO catalysis for upgrading cellulase cocktails to further improvecellulose degradation efficiency.