New glucuronoyl esterases for wood processing
Conference poster, 2015
The development of new wood-based materials is of great interest to the forest industry. Wood tissue is composed of a complex biopolymer mixture containing cellulose, hemicellulose and lignin. Covalent bonds between lignin and different polysaccharides form closely associated structures known as lignin-carbohydrate complexes (LCCs). As a result, the successful extraction and separation of wood polymers poses a major challenge for materials biorefinery concepts. Enzymes that target lignin-carbohydrate (LC) bonds are especially useful for biorefinery applications as they can facilitate the isolation of individual wood components in combination with mild chemical treatments.
The main LCCs present in wood are believed to be esters, benzyl ethers and phenyl glycosides [1,2]. Glucuronoyl esterases (GEs) have been proposed to degrade ester bonds between glucuronic acids in xylans and lignin alcohols. GEs belong to the carbohydrate esterase (CE) 15 family and are present in the genomes of a wide range of fungi and bacteria.
The aims of our study were to characterize new GE enzymes, to investigate their capacity in disconnecting hemicellulose from lignin and to apply them in the extraction process. Selected candidate genes encoding novel GEs from a diverse range of filamentous fungi were produced in the eukaryotic enzyme production host Pichia pastoris. Purified enzymes were tested on model substrates as well as LCC fractions and their applicability in wood processing is investigated.
Research on glucuronoyl esterases at Chalmers is funded by the Knut and Alice Wallenberg Foundation. Selection of candidate genes was performed in the context of OPTIBIOCAT (FP7 KBBE. 2013.3.3-04), which is gratefully acknowledged.
1. Balakshin MY, et at. (2007) MWL fraction with a high concentration of lignin-carbohydrate linkages: Isolation and 2D NMR spectroscopic analysis. Holzforschung 61:1–7.
2. Watanabe T (1995) Important properties of lignin-carbohydrates complexes (LCCs) in environmentally safe paper making. Trends in Glycoscience and Glycotechnology 7:57–68.