Detection and characterization of a novel extracellular fungal enzyme that catalyzes the specific and hydrolytic cleavage of lignin guaiacylglycerol β-aryl ether linkages

Abstract

Cleavage of the arylglycerol β-aryl ether linkage is the most important process in the biological degradation of lignin. The bacterial β-etherase was described previously and shown to be tightly associated with the cellular membrane. In this study, we aimed to detect and isolate a new extracellular function that catalyses the β-aryl ether linkage cleavage of high-molecular lignin in the soil fungi. We screened and isolated 2BW-1 cells by using a highly sensitive fluorescence assay system. The β-aryl ether cleavage enzyme was produced by a newly isolated fungus, 2BW-1, and is secreted into the extracellular fraction. The β-aryl ether cleavage enzyme converts the guaiacylglycerol β-O-guaiacyl ether (GOG) to guaiacylglycerol and guaiacol. It requires the Cα alcohol structure and p-hydroxyl group and specifically attacks the β-aryl ether linkage of high-molecular mass lignins with addition of two water molecules at the Cα and Cβ positions.