Title: Restricting lignin and enhancing sugar deposition in secondary cell walls enhances monomeric sugar release after low temperature ionic liquid pretreatment

Abstract

© 2015 Scullin et al. Background: Lignocellulosic biomass has the potential to be a major source of renewable sugar for biofuel production. Before enzymatic hydrolysis, biomass must first undergo a pretreatment step in order to be more susceptible to saccharification and generate high yields of fermentable sugars. Lignin, a complex, interlinked, phenolic polymer, associates with secondary cell wall polysaccharides, rendering them less accessible to enzymatic hydrolysis. Herein, we describe the analysis of engineered Arabidopsis lines where lignin biosynthesis was repressed in fiber tissues but retained in the vessels, and polysaccharide deposition was enhanced in fiber cells with little to no apparent negative impact on growth phenotype. Results: Engineered Arabidopsis plants were treated with the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate 1-ethyl-3-methylimidazolium acetate ([C2C1im][OAc]) at 10 % wt biomass loading at either 70 °C for 5 h or 140 °C for 3 h. After pretreatment at 140 °C and subsequent saccharification, the relative peak sugar recovery of ~26.7 g sugar per 100 g biomass was not statistically different for the wild type than the peak recovery of ~25.8 g sugar per 100 g biomass for the engineered plants (84 versus 86 % glucose from the starting biomass). Reducing the pretreatment temperature tomore » 70 °C for 5 h resulted in a significant reduction in the peak sugar recovery obtained from the wild type to 16.2 g sugar per 100 g biomass, whereas the engineered lines with reduced lignin content exhibit a higher peak sugar recovery of 27.3 g sugar per 100 g biomass and 79 % glucose recoveries. Conclusions: The engineered Arabidopsis lines generate high sugar yields after pretreatment at 70 °C for 5 h and subsequent saccharification, while the wild type exhibits a reduced sugar yield relative to those obtained after pretreatment at 140 °C. Our results demonstrate that employing cell wall engineering efforts to decrease the recalcitrance of lignocellulosic biomass has the potential to drastically reduce the energy required for effective pretreatment.« less

Authors:

Scullin, Chessa ^[1]; Cruz, Alejandro G. ^[2]; Chuang, Yi -De ^[2]; Simmons, Blake A. ^[1]; Loque, Dominique ^[2]; Singh, Seema ^[3]

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+ Show Author Affiliations

1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sandia National Lab., Livermore, CA (United States)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sandia National Lab., Livermore, CA (United States); Joint BioEnergy Institute, Emeryville, CA (United States)

Publication Date:

Sat Jul 04 00:00:00 EDT 2015

Research Org.:

Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23), Biological Systems Science Division (SC-23.2 )

OSTI Identifier:

1213400

Alternate Identifier(s):

OSTI ID: 1512211

Grant/Contract Number:  

AC04-94AL85000; AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Biotechnology for Biofuels

Additional Journal Information:

Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 1754-6834

Publisher:

BioMed Central

Country of Publication:

United States

Language:

English

Subject:

09 BIOMASS FUELS; 60 APPLIED LIFE SCIENCES; Arabidopsis; biofuels; cell wall; lignin; saccharification; ionic liquid