Abstract: [Objective] As a main white-rot fungus, Irpex lacteus shows very strong wood degradation ability. Here, we analyzed and measured the activities of five extracellular lignocellulolytic enzymes and intracellular proteome of Irpex lacteus induced by birch and spruce wood sawdust to explore the mechanism of substrate utilization by this fungus and provide more information and scientific basis for screening high efficient strains in biological pulping, prevention of forest disease and degradation of industrial pollutants.[Method] We measured the activities of five main extracellular lignocellulolytic enzymes and the changes the of intracellular proteome of I. lacteus subjected to birch(Betula playtyphylla) or spruce(Picea korainsis) sawdust or no sawdust (served as control).[Result] The enzyme activities induced by sawdust were higher than that of the control. There were significant differences in the manganese-peroxidase and laccase activities between the sawdust-treatments and control. The laccase activity was the highest among ligninolytic enzymes, followed by lignin-peroxidase activity, and manganese-peroxidase activity was the lowest. The exoglucanase activity was much higher than that of endoglucanase in the cellulose degrading enzymes. Compared with the control, 32 proteins with significantly differential expression were detected after being induced by sawdust. Three differential expression proteins were found in different substrates. Among these differential expression proteins, the proteins induced by birch sawdust were involved with membrane protein, membrane transportation and energy, while the proteins induced by spruce sawdust were all related with protein synthesis.[Conclusion] The lignocellulolytic enzymes activities and intracellular proteome of I. lacteus induced by different substrates were significantly different. Thus, the membrane transportation of secretory proteins could be a key in determining birch wood-decaying ability of I. lacteus, while the protein synthesis would play an important role in degrading spruce.

Key words: Irpex lacteus, extracellular protease, intracellular proteome, lignocellulose enzyme, differential expression