The impact of endogenous acetylation on the deconstruction of Populus trichocarpa wood during pretreatment

Wood is a renewable, sustainable and economic resource. Non-cellulosic wood polysaccharides are acetylated in a species-dependent and spatially-regulated manner. Acetyl groups comprise approximately 5% of the dry weight of poplar wood. Biologically, acetyl groups increase xylan chain solubility and may therefore influence secondary cell wall formation by affecting the association of hemicelluloses with the other cell wall components, such as cellulose, lignin, and the pectic and proteinaceous constituents of the adjacent primary cell wall. In this research, we found that acetyl content correlated positively with lignin (R = 0.28) and negatively with cellulose (R = -0.41) in wood samples from a common garden of over 200 unrelated Populus trichocarpa individuals. During the pretreatment of biomass, acetyl groups are hydrolyzed from wood to form free acetic acid in the reaction media. The present research examined the relationships between wood composition and pretreatment sugar yield of 19 P. trichocarpa genotypes with varying levels of acetylation. The results clearly show a strong correlation (R > 0.77) between acetic acid and polysaccharide dissolution. Fast-reacting xylan had a degree of acetylation of 0.35, while slow-reacting xylan had a degree of acetylation of 0.73. Hydrophobic interactions could explain the negative correlation between lignin content and acetic acid released (R = -0.59). This research highlights the impact acetylation may have on the large-scale industrial utility of plants.Forestry, Faculty ofGraduat