Comparison of Dilute Acid and Sulfite Pretreatment for Enzymatic Saccharification of Earlywood and Latewood of Douglas fir
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This study applied dilute acid (DA) and sulfite pretreatment to overcome the recalcitrance of lignocelluloses (SPORL) to deconstruct earlywood and latewood cell walls of Douglas fir for fermentable sugars production through subsequent enzymatic hydrolysis. DA pretreatment removed almost all the hemicelluloses, while SPORL at initial pH = 4.5 (SP-B) removed significant amount of lignin between 20 and 25 %. But both are not sufficient for effective enzymatic saccharification. SPORL at low initial pH = 2 (SP-AB) combines the advantage of both DA and SPORL-B to achieve approximately 90 % hemicellulose removal and delignification of 10–20 %. As a result, SP-AB effectively removed recalcitrance and thereby significantly improved enzymatic saccharification compared with DA and SP-B. Results also showed that earlywood with significantly lower density produced less saccharification after DA pretreatment, suggesting that wood density does not contribute to recalcitrance. The thick cell wall of latewood did not limit chemical penetration in pretreatments. The high lignin content of earlywood limited the effectiveness of DA pretreatment for enzymatic saccharification, while hemicellulose limits the effectiveness of high pH pretreatment of SP-B. The higher hemicellulose content in the earlywood and latewood of heartwood reduced saccharification relative to the corresponding earlywood and latewood in the sapwood using DA and SP-AB.
KeywordsCell walls Pretreatment Enzymatic hydrolysis, earlywood and latewood Recalcitrance
This work, as part of the Northwest Advanced Renewables Alliance (NARA), was funded by the Agriculture and Food Research Initiative Competitive Grant No. 2011-68005-30416 from the USDA National Institute of Food and Agriculture (NIFA). We would also like to acknowledge Novozymes North America for their constant support by complementary providing cellulase enzymes. We would also like to thank Fred Matt of USDA Forest Products Laboratory for conducting detailed substrate chemical composition analysis. We also would like to acknowledge Gevan Marrs of Weyerhaeuser NR Company for providing the Douglas wood disk for the study. The financial support from USDA NIFA and the Chinese Scholarship Council made the visiting appointment of Zhang at the USDA Forest Products Laboratory possible.
- 1.Perlack RD, Stokes BJ: DOE. 2011. U.S. billion-ton update: biomass supply for a bioenergy and bioproducts industry. In. Oak Ridge: Oakridge National Laboratory; 2011Google Scholar
- 4.Zhu JY, Scott CT, Scallon KL, Myers GC (2007) Effects of plantation density on wood density and anatomical properties of red pine (Pinus resinosa Ait). Wood Fiber Sci 39(3):502–512Google Scholar
- 8.Pan XJ, Arato C, Gilkes N, Gregg D, Mabee W, Pye K, Xiao ZZ, Zhang X, Saddler J (2005) Biorefining of softwoods using ethanol organosolv pulping: preliminary evaluation of process streams for manufacture of fuel-grade ethanol and co-products. Biotechnol Bioeng 90(4):473–481PubMedCrossRefGoogle Scholar
- 14.Leu S-Y, Gleisner R, Zhu JY, Sessions J, Marrs G: Robust enzymatic saccharification of a Douglas-fir forest harvest residue by SPORL. biomass and bioenergy (submitted) 2013.Google Scholar
- 15.Wood TM, Bhat M: Methods for measuring cellulase activities. In: In: Colowick SP, Kaplan NO, editors Methods in Enzymology, Vol 160, Biomass (Part A, Cellulose and Hemicellulose) Vol editors: Wood WA, Kellogg ST New York: Academic, Inc, p 87–112. 1988: 87–112.Google Scholar
- 16.Zhang C, Houtman CJ, Zhu JY: Using low temperature to balance enzymatic saccharification and furan formation in SPORL pretreatment of Douglas-fir. AIChE J (submitted) 2013.Google Scholar
- 17.Zhang C, Houtman CJ, Zhu JY: Using low temperature to balance enzymatic saccharification and furan formation in SPORL pretreatment of Douglas-fir. Bioresource Technology (submitted) 2013.Google Scholar
- 21.F. B, Graystone JA: Wood coatings: theory and practice. Elsevier; 2009.Google Scholar
- 22.Vahey DW, Zhu JY, Scott CT: Method for characterizing the density and cross-section morphology of trees. US Patent 2011, 7, 945, 098 B2.Google Scholar
- 28.Panshin AJ, de Zeeuw C (1980) Textbook of wood technology 4th edn. McGraw-Hill, New YorkGoogle Scholar