Insights into the H<sub>2</sub>O<sub>2</sub>-Driven Lytic Polysaccharide Monooxygenase Activity on Efficient Cellulose Degradation in the White Rot Fungus <i>Irpex lacteus</i>
Xing Qin, Kun Yang, Xiaolu Wang, Tao Tu, Yuan Wang, Jie Zhang, Xiaoyun Su, Bin Yao, Huoqing Huang, Huiying Luo
Abstract
In contrast to O 2, H 2 O 2 as the cosubstrate for lytic polysaccharide monooxygenases (LPMOs) exhibits great advantages in industrial settings for cellulose degradation. However, H 2 O 2 -driven LPMO reactions from natural microorganisms have not been fully explored and understood. Herein, secretome analysis unraveled the H 2 O 2 -driven LPMO reaction in the efficient lignocellulose-degrading fungus Irpex lacteus, including LPMOs with different oxidative regioselectivities and various H 2 O 2 -generating oxidases. Biochemical characterization of H 2 O 2 -driven LPMO catalysis showed orders of magnitude improvement in catalytic efficiency compared to that of O 2 -driven LPMO catalysis for cellulose degradation. Significantly, H 2 O 2 tolerance of LPMO catalysis in I. lacteus was an order of magnitude higher than that in other filamentous fungi. In addition, natural reductants, gallic acid, in particular, presented in lignocellulosic biomass could sufficiently maintain LPMO catalytic reactions. Moreover, the H 2 O 2 -driven LPMO catalysis exhibited synergy with canonical endoglucanases for efficient cellulose degradation. Taken together, these findings demonstrate the great application potential of the H 2 O 2 -driven LPMO catalysis for upgrading cellulase cocktails to further improve cellulose degradation efficiency.