Abstract
Alkaline induced deacetylation of the hemicellulose combined with subsequent mechanical refining enhanced the enzyme-mediated hydrolysis of pretreated corn stover. The addition of either NaOH (80 °C) or mild KOH (25 °C) to corn stover prior to mechanical refining led to greater than 80% deacetylation with the NaOH treatment also solubilizing low-molecular-weight lignin that was enriched in β-O-4 linkages with more than 25% and 13% of the total and surface lignin removed, respectively. The influence of deacetylation and delignification were further enhanced when NaOH was supplemented with 3% Na2SO3, resulting in 100% deacetylation, 34% delignification, and a >20% increase in the hydrolysis yield of the substrate xylan. A milder KOH treatment resulted in the retention of more than 95% of the lignin within the cellulose rich, water-insoluble fraction with no apparent change in the surface lignin. However, both methods resulted in enhanced xylan hydrolysis when treated with xylanases, suggesting that deacetylation had enhanced accessibility to the xylan present in the pretreated of corn stover. It was apparent that cellulose accessibility was also enhanced by partial delignification, as NaOH treatment resulted in a 65% and 43% increase in the Water Retention Value and Directed Orange dye adsorption, respectively.
| Original language | English |
|---|---|
| Pages (from-to) | 5847-5855 |
| Number of pages | 9 |
| Journal | ACS Sustainable Chemistry and Engineering |
| Volume | 8 |
| Issue number | 15 |
| DOIs | |
| State | Published - Apr 20 2020 |
Funding
The authors are grateful for the financial support from the Natural Science and Engineering Council of Canada (NSERC) and the Korea Institute of Science and Technology (KIST). The authors would also like to thank Novozymes (Davis, CA) for the generous donation of enzymes. Mr. Junjie Wang and Miss Hui Zhu are thanked for their contributions during their stay at the Forest Products Biotechnology/Bioenergy group as research interns. This manuscript has been authored, in part (AJR and YP), by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). The views and opinions of the authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights.
Keywords
- Deacetylation
- Delignification
- Enzyme-mediated hydrolysis
- Increased enzyme accessibility