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Title: Enhanced Softwood Cellulose Accessibility by H 3PO 4 Pretreatment: High Sugar Yield without Compromising Lignin Integrity

Abstract

Softwood lignocellulose is a potential feedstock for the production of biofuels and bioproducts. However, the highly cross-linked nature of softwood lignocellulose restricts enzyme access to its sugars. Thus, harsh pretreatment conditions (180–280 °C) and/or high enzyme loading are required to unlock sugars. These requirements negatively affect the economic viability of softwoods in biorefineries. Here we show that H 3PO 4 pretreatment of pine and Douglas fir under a mild reaction temperature (50 °C) and atmospheric pressure enabled a high (~80%) glucan digestibility with low enzyme loading (5 filter paper units (FPU)/g glucan). The dissolution and regeneration of softwoods disrupted the hydrogen bonding between cellulose chains, thereby increasing the cellulose accessibility to cellulase (CAC) values by ~38-fold (from ~0.4 to 15 m 2/g biomass). Examination of H 3PO 4-pretreated softwoods by cross-polarization/magic angle spin (CP/MAS), 13C- nuclear magnetic resonance (NMR), and Fourier-transform infrared spectroscopy (FTIR) revealed that breaking of the orderly hydrogen bonding of crystalline cellulose caused the increase in CAC (higher than 11 m 2/g biomass), which, in turn, was responsible for the high glucan digestibility of pretreated softwoods. The H 3PO 4 pretreatment process was feedstock independent. Finally, 2D 13C– 1H heteronuclear single quantum coherence (HSQC) NMR showed thatmore » the lignin was depolymerized but not condensed; thus, the lignin can be available for producing high-value products.« less

Authors:
 [1];  [1];  [2];  [1];  [3]; ORCiD logo [4]; ORCiD logo [5];  [6];  [7]; ORCiD logo [8]; ORCiD logo [1]
  1. Univ. of Louisville, KY (United States)
  2. Joint BioEnergy Inst., Emeryville, CA (United States)
  3. King Abdullah University of Science and Technology (KAUST), Thuwal (Saudi Arabia); Univ. of California, Berkeley, CA (United States)
  4. Joint BioEnergy Inst., Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  5. Univ. of British Columbia, Vancouver (Canada)
  6. Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)
  7. Joint BioEnergy Inst., Emeryville, CA (United States); Sandia National Lab. (SNL-CA), Livermore, CA (United States)
  8. Univ. of Louisville, KY (United States); Univ. of Technology Thonburi, Bangkok (Thailand)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1581639
Grant/Contract Number:  
AC02-05CH11231; ECCS-1542174
Resource Type:
Accepted Manuscript
Journal Name:
Industrial and Engineering Chemistry Research
Additional Journal Information:
Journal Name: Industrial and Engineering Chemistry Research; Journal ID: ISSN 0888-5885
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; softwood; biomass; enzymes; accessibility; Lignocellulosic Biomass; Enzymatic hydrolysis

Citation Formats

Hossain, Anwar, Rahaman, Mohammad Shahinur, Lee, David, Phung, Thanh Khoa, Canlas, Christian G., Simmons, Blake A., Renneckar, Scott, Reynolds, William, George, Anthe, Tulaphol, Sarttrawut, and Sathitsuksanoh, Noppadon. Enhanced Softwood Cellulose Accessibility by H3PO4 Pretreatment: High Sugar Yield without Compromising Lignin Integrity. United States: N. p., 2019. Web. doi:10.1021/acs.iecr.9b05873.
Hossain, Anwar, Rahaman, Mohammad Shahinur, Lee, David, Phung, Thanh Khoa, Canlas, Christian G., Simmons, Blake A., Renneckar, Scott, Reynolds, William, George, Anthe, Tulaphol, Sarttrawut, & Sathitsuksanoh, Noppadon. Enhanced Softwood Cellulose Accessibility by H3PO4 Pretreatment: High Sugar Yield without Compromising Lignin Integrity. United States. doi:10.1021/acs.iecr.9b05873.
Hossain, Anwar, Rahaman, Mohammad Shahinur, Lee, David, Phung, Thanh Khoa, Canlas, Christian G., Simmons, Blake A., Renneckar, Scott, Reynolds, William, George, Anthe, Tulaphol, Sarttrawut, and Sathitsuksanoh, Noppadon. Mon . "Enhanced Softwood Cellulose Accessibility by H3PO4 Pretreatment: High Sugar Yield without Compromising Lignin Integrity". United States. doi:10.1021/acs.iecr.9b05873.
@article{osti_1581639,
title = {Enhanced Softwood Cellulose Accessibility by H3PO4 Pretreatment: High Sugar Yield without Compromising Lignin Integrity},
author = {Hossain, Anwar and Rahaman, Mohammad Shahinur and Lee, David and Phung, Thanh Khoa and Canlas, Christian G. and Simmons, Blake A. and Renneckar, Scott and Reynolds, William and George, Anthe and Tulaphol, Sarttrawut and Sathitsuksanoh, Noppadon},
abstractNote = {Softwood lignocellulose is a potential feedstock for the production of biofuels and bioproducts. However, the highly cross-linked nature of softwood lignocellulose restricts enzyme access to its sugars. Thus, harsh pretreatment conditions (180–280 °C) and/or high enzyme loading are required to unlock sugars. These requirements negatively affect the economic viability of softwoods in biorefineries. Here we show that H3PO4 pretreatment of pine and Douglas fir under a mild reaction temperature (50 °C) and atmospheric pressure enabled a high (~80%) glucan digestibility with low enzyme loading (5 filter paper units (FPU)/g glucan). The dissolution and regeneration of softwoods disrupted the hydrogen bonding between cellulose chains, thereby increasing the cellulose accessibility to cellulase (CAC) values by ~38-fold (from ~0.4 to 15 m2/g biomass). Examination of H3PO4-pretreated softwoods by cross-polarization/magic angle spin (CP/MAS), 13C- nuclear magnetic resonance (NMR), and Fourier-transform infrared spectroscopy (FTIR) revealed that breaking of the orderly hydrogen bonding of crystalline cellulose caused the increase in CAC (higher than 11 m2/g biomass), which, in turn, was responsible for the high glucan digestibility of pretreated softwoods. The H3PO4 pretreatment process was feedstock independent. Finally, 2D 13C–1H heteronuclear single quantum coherence (HSQC) NMR showed that the lignin was depolymerized but not condensed; thus, the lignin can be available for producing high-value products.},
doi = {10.1021/acs.iecr.9b05873},
journal = {Industrial and Engineering Chemistry Research},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {12}
}

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This content will become publicly available on December 23, 2020
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