Catalase improves saccharification of lignocellulose by reducing lytic polysaccharide monooxygenase-associated enzyme inactivation

OBJECTIVES: Efficient enzymatic saccharification of plant cell wall material is key to industrial processing of agricultural and forestry waste such as straw and wood chips into fuels and chemicals. RESULTS: Saccharification assays were performed on steam-pretreated wheat straw under ambient and O(2)-deprived environments and in the absence and presence of a lytic polysaccharide monooxygenase (LPMO) and catalase. A kinetic model was used to calculate catalytic rate and first-order inactivation rate constants of the cellulases from reaction progress curves. The addition of a LPMO significantly (P < 0.01, Student’s T test) enhanced the rate of glucose release from 2.8 to 6.9 h(−1) under ambient O(2) conditions. However, this also significantly (P < 0.01, Student’s T test) increased the rate of inactivation of the enzyme mixture, thereby reducing the performance half-life from 65 to 35 h. Decreasing O(2) levels or, strikingly, the addition of catalase significantly reduced (P < 0.01, Student’s T test) enzyme inactivation and, as a consequence, higher efficiency of the cellulolytic enzyme cocktail was achieved. CONCLUSION: Oxidative inactivation of commercial cellulase mixtures is a significant factor influencing the overall saccharification efficiency and the addition of catalase can be used to protect these mixtures from inactivation. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10529-015-1989-8) contains supplementary material, which is available to authorized users.