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

Forest biomass has the potential to provide environmentally-sustainable, carbon-neutral raw material for much of the nation¿s energy and chemical synthesis needs. However, the drawback to the use of wood for chemical production and biofuels continues to be the complexity of producing separate streams of cellulose, hemicellulose, and/or lignin from the lignocellulosic feedstock. The major difficulty in fractionating wood is due to ether bonds between the lignin and hemicellulose components of wood. Current commercial wood fractionation practices in the pulp and paper industry use primarily chemical means to break these ether bonds. However, these methods have many disadvantages: they damage cellulose fibers; do not cleanly separate the constituent cellulose, hemicellulose, and lignin; and pose serious environmental challenges. Although several enzymes are known to be able to break down the wood, they do so by generating free radicals, which also can break crosslinks between wood components, significantly reducing product yield. Previous research led to the discovery of three microorganisms that are potential sources of enzymes that can specifically break the ether bonds. Because these organisms also are likely to produce other enzymes that break down hemicellulose and cellulose, this project will isolate the etherase activity, leading to the design of a pulping process in which the target enzyme can be used for wood fractionation. In Phase I, the etherase activity will be isolated from one of these microorganisms, the enzyme will be tested for its activity against lignin-hemicellulose complexes, and its identity will be determined. Phase II will design and test a pilot scale pretreatment process for pulping mills, which will increase the efficiency of delignification of softwood and generate feedstreams of lignin and hemicellulose. Commercial Applications and other Benefits as described by the awardee: The technology should have immediate applicability to the producers of the more than 100 million tons of chemical pulp produced worldwide annually. Currently, the production of a softwood pulp with a kappa number of 30 provides a yield of about 40%. Since typical mills produce approximately 1000 tons of pulp per day, valued at about $450/ton, a 5% increase would increase the gross revenue of a typical mill by $22,500 per day or approximately $7,875,000 per annum. The technology also has the potential to reduce harmful land fragmentation and enable conservation efforts that result in the protection of additional natural resources. Finally, the new technology would enable the production of biofuels, thereby mitigating the rising price of fuel and the volatility of the oil market.