the impacts of deacetylation prior to dilute acid pretreatment on the bioethanol process稀酸预处理前脱乙酰作用的影响的生物乙醇的过程.pdf

Chen et al. Biotechnology for Biofuels 2012, 5:8 /content/5/1/8 RESEARCH Open Access The impacts of deacetylation prior to dilute acid pretreatment on the bioethanol process 1* 1 1 2 1 1 2 Xiaowen Chen , Joseph Shekiro , Mary Ann Franden , Wei Wang , Min Zhang , Erik Kuhn , David K Johnson and Melvin P Tucker1 Abstract Background: Dilute acid pretreatment is a promising pretreatment technology for the biochemical production of ethanol from lignocellulosic biomass. During dilute acid pretreatment, xylan depolymerizes to form soluble xylose monomers and oligomers. Because the xylan found in nature is highly acetylated, the formation of xylose monomers requires two steps: 1) cleavage of the xylosidic bonds, and 2) cleavage of covalently bonded acetyl ester groups. Results: In this study, we show that the latter may be the rate limiting step for xylose monomer formation. Furthermore, acetyl groups are also found to be a cause of biomass recalcitrance and hydrolyzate toxicity. While the removal of acetyl groups from native corn stover by alkaline de-esterification prior to pretreatment improves overall process yields, the exact impact is highly dependent on the corn stover variety in use. Xylose monomer yields in pretreatment generally increases by greater than 10%. Compared to pretreated corn stover controls, the deacetylated corn stover feedstock is approximately 20% more digestible after pretreatment. Finally, by lowering hydrolyzate toxicity, xylose utilization and ethanol yields are further improved during fermentation by roughly 10% and 7%, respectively. In this study, several varieties of corn stover lots were investigated to test the robustnes