Hemicellulose: Lignin Etherase from Microbe B603:Feasibility of Isolation to Fractionate Wood for Chemicals

American forests have the potential to provide environmentally sustainable, carbon-neutral raw material for much of the nation¿s energy and chemical synthesis needs. However, wood has not been used to produce chemicals and biofuels because current technology cannot efficiently separate cellulose, hemicelluloses, and lignin (the major components of wood) for downstream processing. The major difficulty in fractionating wood is breaking the ether bonds between the lignin and hemicelluloses components. Currently, pulp and paper mills rely primarily on chemical means to break these bonds, but chemical methods have many disadvantages: damage to cellulose fibers; inability to cleanly separate the constituents; and serious environmental challenges. In this project, a fluorogenic model compound based on hemicelluloses will be used to bioprospect for enzymes that cleave the ether bonds between lignin and hemicelluloses. In Phase I, a microorganism designated B603 that secretes an enzyme capable of breaking ether bonds has been discovered. The enzyme was isolated, and its activity on native lignin-hemicelluloses complexes was verified. In Phase II, processes will be developed to (1) apply the enzyme to the pre-treatment of wood chips in pulp mills; and (2) more efficiently convert wood into chemicals, for use in integrated forest biorefineries. Finally, molecular biology techniques will be used to facilitate the large scale production of the enzyme. Commercial Applications and Other Benefits as described by the awardee: As a pre-treatment for wood chips in a pulp mill, the new enzyme should allow previously wasted hemicelluloses to be recovered and added back to the pulp, thereby increasing yield. Alternatively, the hemicellulose could be converted via fermentation into an array of fine chemicals and energy products, including ethanol. Broadly speaking, the technology would allow wood, a renewable resource, to be used to meet a significant portion of America¿s energy and chemical needs. As a consequence, the corn currently slated for ethanol production could again be directed to food products, and America¿s pulp and paper industry (and the rural towns where mills are located) would receive a much needed economic boost.