Previous studies defined easy and difficult to hydrolyze fractions of hemicellulose that may result from bonds among cellulose, hemicellulose, and lignin. To understand how such bonds affect hydrolysis, Populus trichocarpa×. Populus deltoides, holocellulose isolated from P. trichocarpa×. P. deltoides and birchwood xylan were subjected to hydrothermal flow-through pretreatment. Samples were characterized by glycome profiling, HPLC, and UPLC-MS. Glycome profiling revealed steady fragmentation and removal of glycans from solids during hydrolysis. The extent of polysaccharide fragmentation, hydrolysis rate, and total xylose yield were lowest for P. trichocarpa×. P. deltoides and greatest for birchwood xylan. Comparison of results from P. trichocarpa×. P. deltoides and holocellulose suggested that lignin-carbohydrate complexes reduce hydrolysis rates and limit release of large xylooligomers. Smaller differences between results with holocellulose and birchwood xylan suggest xylan-cellulose hydrogen bonds limited hydrolysis, but to a lesser extent. These findings imply cell wall structure strongly influences hydrolysis.
Trajano, H. L., Pattathil, S., Tomkins, B. A., Tschaplinski, T. J., Hahn, M. G., Van Berkel, G. J., & Wyman, C. E. (2015). Xylan hydrolysis in Populus trichocarpa×P. deltoides and model substrates during hydrothermal pretreatment. Bioresource Technology, 179, 202–210. https://doi.org/10.1016/j.biortech.2014.11.090