Hemicellulose from wood, a waste product in papermaking, can be utilized for production of biofuels.  However, ether bonds between lignin and hemicellulose are a major impediment to their extraction and subsequent efficient fermentation.  Because of the nature of the biosynthesis of the wood matrix, we hypothesize that these cross-links are non-glycosidic.  Because naturally-occurring organisms can completely degrade wood, we conclude that naturally-occurring organisms express enzymes that can break non-glycosidic ether bonds between lignin and hemicellulose, and that these hemicellulose:lignin etherases (HLEs) can be exploited commercially to aid in fractionation of wood into cellulose, hemicellulose and lignin.
A novel polymeric fluorogenic model compound that mimics non-glycosidic phenolic ether bonds between lignin and galactomannan was developed.  Commercial cellulases and hemicellulases, which are specific for glycosidic bonds, do not cleave the model substrate.  The model substrate was used in bioprospecting experiments to isolate several organisms that appear to express an HLE activity.  We have characterized in particular the activity expressed by Microbe B603, a small, aerobic autofluorescent organism that has not been previously described.  We have demonstrated that the activity is due to an enzyme.  The enzyme is heat tolerant, requires a mineral co-factor, and is inactive against the commercial substrates used to assay for several glycosidases.  The enzyme activity has been shown to be expressed in a cyclical pattern with a periodicity of approximately 27 hours.  The cDNA for the enzyme has been cloned from an expression library based on the activity of its fusion protein against the model substrate.