Article

Increasing cellulose accessibility is more important than removing lignin: A comparison of cellulose solvent-based lignocellulose fractionation and soaking in aqueous ammonia

  1. Joseph A. Rollin1,
  2. Zhiguang Zhu1,
  3. Noppadon Sathitsuksanoh1,2,
  4. Y.-H. Percival Zhang1,2,3,*

Article first published online: 30 SEP 2010

DOI: 10.1002/bit.22919

Issue

Biotechnology and Bioengineering

Biotechnology and Bioengineering

Volume 108, Issue 1, pages 22–30, January 2011

Additional Information

How to Cite

Rollin, J. A., Zhu, Z., Sathitsuksanoh, N. and Zhang, Y.-H. P. (2011), Increasing cellulose accessibility is more important than removing lignin: A comparison of cellulose solvent-based lignocellulose fractionation and soaking in aqueous ammonia. Biotechnol. Bioeng., 108: 22–30. doi: 10.1002/bit.22919

Author Information

  1. 1

    Biological Systems Engineering Department, Virginia Polytechnic Institute and State University, 210-A Seitz Hall, Blacksburg, Virginia 24061; telephone: 1-540-231-7414; fax: +1-540-231-3199

  2. 2

    Institute for Critical Technology and Applied Sciences (ICTAS), Virginia Polytechnic Institute and State University, Blacksburg, Virginia

  3. 3

    DOE BioEnergy Science Center (BESC), Oak Ridge, Tennessee

*Biological Systems Engineering Department, Virginia Polytechnic Institute and State University, 210-A Seitz Hall, Blacksburg, Virginia 24061; telephone: 1-540-231-7414; fax: +1-540-231-3199.

Publication History

  1. Issue published online: 21 NOV 2010
  2. Article first published online: 30 SEP 2010
  3. Accepted manuscript online: 1 SEP 2010 12:00AM EST
  4. Manuscript Accepted: 17 AUG 2010
  5. Manuscript Revised: 11 AUG 2010
  6. Manuscript Received: 18 MAY 2010

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Keywords:

  • biofuels;
  • biomass pretreatment;
  • cellulose solvent- and organic solvent-based lignocellulose fractionation (COSLIF);
  • cellulose accessibility to cellulase;
  • lignin removal;
  • soaking in aqueous ammonia (SAA)

Abstract

While many pretreatments attempt to improve the enzymatic digestibility of biomass by removing lignin, this study shows that improving the surface area accessible to cellulase is a more important factor for achieving a high sugar yield. Here we compared the pretreatment of switchgrass by two methods, cellulose solvent- and organic solvent-based lignocellulose fractionation (COSLIF) and soaking in aqueous ammonia (SAA). Following pretreatment, enzymatic hydrolysis was conducted at two cellulase loadings, 15 filter paper units (FPU)/g glucan and 3 FPU/g glucan, with and without BSA blocking of lignin absorption sites. The hydrolysis results showed that the lignin remaining after SAA had a significant negative effect on cellulase performance, despite the high level of delignification achieved with this pretreatment. No negative effect due to lignin was detected for COSLIF-treated substrate. SEM micrographs, XRD crystallinity measurements, and cellulose accessibility to cellulase (CAC) determinations confirmed that COSLIF fully disrupted the cell wall structure, resulting in a 16-fold increase in CAC, while SAA caused a 1.4-fold CAC increase. A surface plot relating the lignin removal, CAC, and digestibility of numerous samples (both pure cellulosic substrates and lignocellulosic materials pretreated by several methods) was also developed to better understand the relative impacts of delignification and CAC on glucan digestibility. Biotechnol. Bioeng. 2011; 108:22–30. © 2010 Wiley Periodicals, Inc.

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