Expression of a fungal glucuronoyl esterase in Populus: Effects on wood properties and saccharification efficiency

Glucuronoyl esterase PcGCE from white-rot fungus Phanerochaete carnosa, an enzyme thought to hydrolyse the ester links between glucuronoyl substituents of xylan and alcohol groups in lignin, was overexpressed in hybrid aspen. The transgenic plants exhibited substantial increase in wood lignification. Enzymatic hydrolysis of cellulose in lignocellulose from the PcGCE-overexpressing lines was expectedly reduced. However, the acidic pretreatment efficiently removed the inhibitory effects of lignin and the enzymatic hydrolysis following the acid pretreatment resulted in increased cellulose conversion by about 12% in the transgenic lines. This result indicates that intermolecular cross-linking targeted by PcGCE inhibits enzymatic digestibility of lignocellulose.