AUTHOR=Yao Lan , Yang Haitao , Yoo Chang Geun , Meng Xianzhi , Pu Yunqiao , Hao Naijia , Ragauskas Arthur J. 

TITLE=Characteristics of Lignin Fractions from Dilute Acid Pretreated Switchgrass and Their Effect on Cellobiohydrolase from Trichoderma longibrachiatum

JOURNAL=Frontiers in Energy Research

VOLUME=6

YEAR=2018

URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2018.00001

DOI=10.3389/fenrg.2018.00001

ISSN=2296-598X

ABSTRACT=<p>To investigate the interactions between acid pretreated switchgrass lignin and cellobiohydrolase (CBH), three different lignin fractions were isolated from dilute acid pretreated switchgrass by (i) ethanol extraction, followed by (ii) dioxane/H<sub>2</sub>O extraction, and (iii) cellulase treatment, respectively. Structural properties of each lignin fraction were elucidated by GPC, <sup>13</sup>C-NMR, and 2D-HSQC NMR analyses. The adsorptions of CBH to the isolated lignin fractions were also studied by Langmuir adsorption isotherms. Ethanol-extractable lignin fraction, mainly composed of syringyl (S) and guaiacyl (G) units, had the lowest molecular weight, while dioxane/H<sub>2</sub>O-extracted lignin fraction had the lowest S/G ratio with higher content of <italic>p</italic>-coumaric acid (<italic>p</italic>CA) unit. The residual lignin fraction after enzymatic treatment had the highest S/G ratio without hydroxyphenyl (H) unit. Strong associations were found between lignin properties such as lignin composition and S/G ratio and its non-productive enzyme adsorption factors including the maximum adsorption capacity and binding strength.</p>