Monday, April 30, 2007

Bioconversion of mountain pine beetle killed lodgepole pine using steam-explosion and organosolv-ethanol pretreatment

Richard Chandra1, Shannon Ewanick1, Dexter Lam1, Maobing Tu2, Alex Berlin1, Renata Bura3, Xuejun Pan4, and Jack Saddler1. (1) Wood Science, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada, (2) Pulp and Paper Research Institute of Canada (Paprican), 570 Boul. St-Jean, Pointe Claire, QC H9R 3J9, Canada, (3) College of Forest Resources, University of Washington, Winkwnwerder 104, Seattle, WA 98195-2100, (4) Biological Systems Engineering, University of Wisconsin, 460 Henry Mall, Madison, WI 53706

It is expected that approximately 80 percent of British Columbia's lodgepole pine (LP) forest will be killed by Mountain Pine Beetles (MPB) by the year 2013. With the impending surplus of MPB-killed wood, it is vital to develop protocols for recovering maximum value from this resource. In alignment with this initiative, the use of MPB “killed” LP for bioconversion to fuel and potentially valuable chemical by-products has become a major area of research in our group. After exploring a range of pretreatment options to contend with the LP feedstocks, we have decided to utilize steam explosion and ethanol-organosolv, since both pretreatment processes effectively treat softwoods such as LP, while organosolv also isolates the lignin component for potential co-product applications. Using both beetle-killed lodgepole pine (BKLP) and healthy-LP feedstocks, the initial work compared the ability of the steam explosion and organosolv pretreatments to recover the lignin, hemicellulose and cellulose components, while producing substrates amenable to hydrolysis and fermentation. We also investigated the possibility of recycling cellulases during the hydrolysis of the pretreated BKLP substrates. After hydrolysis, the inherent properties of the pretreated BKLP facilitated the recovery of cellulases that were successfully applied in subsequent hydrolysis experiments. The results of this study support the use of either the organosolv or steam explosion pretreatment processes for the effective bioconversion of beetle-killed lodgepole pine.