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Title: Improved sugar yields from biomass sorghum feedstocks: comparing low-lignin mutants and pretreatment chemistries

Abstract

For biofuel production processes to be economically efficient, it is essential to maximize the production of monomeric carbohydrates from the structural carbohydrates of feedstocks. One strategy for maximizing carbohydrate production is to identify less recalcitrant feedstock cultivars by performing some type of experimental screening on a large and diverse set of candidate materials, or by identifying genetic modifications (random or directed mutations or transgenic plants) that provide decreased recalcitrance. Economic efficiency can also be increased using additional pretreatment processes such as deacetylation, which uses dilute NaOH to remove the acetyl groups of hemicellulose prior to dilute acid pretreatment. In this work, we used a laboratory-scale screening tool that mimics relevant thermochemical pretreatment conditions to compare the total sugar yield of three near-isogenic brown midrib (bmr) mutant lines and the wild-type (WT) sorghum cultivar. We then compared results obtained from the laboratory-scale screening pretreatment assay to a large-scale pretreatment system. After pretreatment and enzymatic hydrolysis, the bmr mutants had higher total sugar yields than the WT sorghum cultivar. Increased pretreatment temperatures increased reactivity for all sorghum samples reducing the differences observed at lower reaction temperatures. Deacetylation prior to dilute acid pretreatment increased the total sugar yield for all four sorghum samples,more » and reduced the differences in total sugar yields among them, but solubilized a sizable fraction of the non-structural carbohydrates. The general trends of increased total sugar yield in the bmr mutant compared to the WT seen at the laboratory scale were observed at the large-scale system. However, in the larger reactor system, the measured total sugar yields were lower and the difference in total sugar yield between the WT and bmr sorghum was larger. Sorghum bmr mutants, which have a reduced lignin content showed higher total sugar yields than the WT cultivar after dilute acid pretreatment and enzymatic hydrolysis. In conclusion, deacetylation prior to dilute acid pretreatment increased the total sugar yield for all four sorghum samples. However, since deacetylation also solubilizes a large fraction of the non-structural carbohydrates, the ability to derive value from these solubilized sugars will depend greatly on the proposed conversion process.« less

Authors:
 [1];  [2];  [3];  [4];  [4]; ORCiD logo [2]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States). National Bioenergy Center; Walloon Agricultural Research Center (CRA-W), Gembloux (Belgium)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States). National Bioenergy Center
  3. U.S. Dept. of Agriculture (USDA) and Univ. of Nebraska, Lincoln, NE (United States)
  4. alloon Agricultural Research Center (CRA-W), Gembloux (Belgium)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies Office (EE-3B); Walloon Agricultural Research Center, Belgium
OSTI Identifier:
1335583
Report Number(s):
NREL/JA-5100-67543
Journal ID: ISSN 1754-6834
Grant/Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Biotechnology for Biofuels
Additional Journal Information:
Journal Volume: 9; Journal Issue: 1; Journal ID: ISSN 1754-6834
Publisher:
BioMed Central
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; sorghum bicolor; brown midrib; pretreatment; total sugar yield; biofuels

Citation Formats

Godin, Bruno, Nagle, Nick, Sattler, Scott, Agneessens, Richard, Delcarte, Jérôme, and Wolfrum, Edward. Improved sugar yields from biomass sorghum feedstocks: comparing low-lignin mutants and pretreatment chemistries. United States: N. p., 2016. Web. doi:10.1186/s13068-016-0667-y.
Godin, Bruno, Nagle, Nick, Sattler, Scott, Agneessens, Richard, Delcarte, Jérôme, & Wolfrum, Edward. Improved sugar yields from biomass sorghum feedstocks: comparing low-lignin mutants and pretreatment chemistries. United States. doi:10.1186/s13068-016-0667-y.
Godin, Bruno, Nagle, Nick, Sattler, Scott, Agneessens, Richard, Delcarte, Jérôme, and Wolfrum, Edward. Mon . "Improved sugar yields from biomass sorghum feedstocks: comparing low-lignin mutants and pretreatment chemistries". United States. doi:10.1186/s13068-016-0667-y. https://www.osti.gov/servlets/purl/1335583.
@article{osti_1335583,
title = {Improved sugar yields from biomass sorghum feedstocks: comparing low-lignin mutants and pretreatment chemistries},
author = {Godin, Bruno and Nagle, Nick and Sattler, Scott and Agneessens, Richard and Delcarte, Jérôme and Wolfrum, Edward},
abstractNote = {For biofuel production processes to be economically efficient, it is essential to maximize the production of monomeric carbohydrates from the structural carbohydrates of feedstocks. One strategy for maximizing carbohydrate production is to identify less recalcitrant feedstock cultivars by performing some type of experimental screening on a large and diverse set of candidate materials, or by identifying genetic modifications (random or directed mutations or transgenic plants) that provide decreased recalcitrance. Economic efficiency can also be increased using additional pretreatment processes such as deacetylation, which uses dilute NaOH to remove the acetyl groups of hemicellulose prior to dilute acid pretreatment. In this work, we used a laboratory-scale screening tool that mimics relevant thermochemical pretreatment conditions to compare the total sugar yield of three near-isogenic brown midrib (bmr) mutant lines and the wild-type (WT) sorghum cultivar. We then compared results obtained from the laboratory-scale screening pretreatment assay to a large-scale pretreatment system. After pretreatment and enzymatic hydrolysis, the bmr mutants had higher total sugar yields than the WT sorghum cultivar. Increased pretreatment temperatures increased reactivity for all sorghum samples reducing the differences observed at lower reaction temperatures. Deacetylation prior to dilute acid pretreatment increased the total sugar yield for all four sorghum samples, and reduced the differences in total sugar yields among them, but solubilized a sizable fraction of the non-structural carbohydrates. The general trends of increased total sugar yield in the bmr mutant compared to the WT seen at the laboratory scale were observed at the large-scale system. However, in the larger reactor system, the measured total sugar yields were lower and the difference in total sugar yield between the WT and bmr sorghum was larger. Sorghum bmr mutants, which have a reduced lignin content showed higher total sugar yields than the WT cultivar after dilute acid pretreatment and enzymatic hydrolysis. In conclusion, deacetylation prior to dilute acid pretreatment increased the total sugar yield for all four sorghum samples. However, since deacetylation also solubilizes a large fraction of the non-structural carbohydrates, the ability to derive value from these solubilized sugars will depend greatly on the proposed conversion process.},
doi = {10.1186/s13068-016-0667-y},
journal = {Biotechnology for Biofuels},
number = 1,
volume = 9,
place = {United States},
year = {Mon Nov 21 00:00:00 EST 2016},
month = {Mon Nov 21 00:00:00 EST 2016}
}

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Works referenced in this record:

Compositional Analysis of Lignocellulosic Feedstocks. 1. Review and Description of Methods
journal, August 2010

  • Sluiter, Justin B.; Ruiz, Raymond O.; Scarlata, Christopher J.
  • Journal of Agricultural and Food Chemistry, Vol. 58, Issue 16, p. 9043-9053
  • DOI: 10.1021/jf1008023

Process and technoeconomic analysis of leading pretreatment technologies for lignocellulosic ethanol production using switchgrass
journal, December 2011