title: Ethylenediamine pretreatment changes cellulose allomorph and lignin structure of lignocellulose at ambient pressure.
abstract: BACKGROUND
  Pretreatment of lignocellulosic biomass is essential to increase the cellulase accessibility for bioconversion of lignocelluloses by breaking down the biomass recalcitrance. In this work, a novel pretreatment method using ethylenediamine (EDA) was presented as a simple process to achieve high enzymatic digestibility of corn stover (CS) by heating the biomass-EDA mixture with high solid-to-liquid ratio at ambient pressure. The effect of EDA pretreatment on lignocellulose was further studied.
  
  
  RESULTS
  High enzymatic digestibility of CS was achieved at broad pretreatment temperature range (40-180 °C) during EDA pretreatment. Herein, X-ray diffractogram analysis indicated that cellulose I changed to cellulose III and amorphous cellulose after EDA pretreatment, and cellulose III content increased along with the decrease of drying temperature and the increase of EDA loading. Lignin degradation was also affected by drying temperature and EDA loading. Images from scanning electron microscope and transmission electron microscope indicated that lignin coalesced and deposited on the biomass surface during EDA pretreatment, which led to the delamination of cell wall. HSQC NMR analysis showed that ester bonds of p-coumarate and ferulate units in lignin were partially ammonolyzed and ether bonds linking the phenolic monomers were broken during pretreatment. In addition, EDA-pretreated CS exhibited good fermentability for simultaneous saccharification and co-fermentation process.
  
  
  CONCLUSIONS
  EDA pretreatment improves the enzymatic digestibility of lignocellulosic biomass significantly, and the improvement was caused by the transformation of cellulose allomorph, lignin degradation and relocalization in EDA pretreatment.
authors.affiliation: Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Weijin Road 92, Nankai District, Tianjin, 300072 People's Republic of China ; SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Nankai District, Tianjin 300072 People's Republic of China.
authors.forename: Lei
authors.initials: L
authors.lastname: Qin
authors.affiliation: Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Weijin Road 92, Nankai District, Tianjin, 300072 People's Republic of China ; SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Nankai District, Tianjin 300072 People's Republic of China.
authors.forename: Wen-Chao
authors.initials: WC
authors.lastname: Li
authors.affiliation: Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Weijin Road 92, Nankai District, Tianjin, 300072 People's Republic of China ; SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Nankai District, Tianjin 300072 People's Republic of China.
authors.forename: Jia-Qing
authors.initials: JQ
authors.lastname: Zhu
authors.affiliation: Institute of Microbiology Chinese Academy of Sciences, No.1 West Beichen Road, Chaoyang District, Beijing, 100101 People's Republic of China.
authors.forename: Jing-Nan
authors.initials: JN
authors.lastname: Liang
authors.affiliation: Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Weijin Road 92, Nankai District, Tianjin, 300072 People's Republic of China ; SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Nankai District, Tianjin 300072 People's Republic of China.
authors.forename: Bing-Zhi
authors.initials: BZ
authors.lastname: Li
authors.affiliation: Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Weijin Road 92, Nankai District, Tianjin, 300072 People's Republic of China ; SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Nankai District, Tianjin 300072 People's Republic of China.
authors.forename: Ying-Jin
authors.initials: YJ
authors.lastname: Yuan
keywords: Biomass; Cellulose; Ethylenediamine; Hydrolysis; Lignin; Pretreatment