Biotechnol Biofuels. 2016 Feb 09;9:34. doi: 10.1186/s13068-016-0442-0. eCollection 2016.
Effective alkaline metal-catalyzed oxidative delignification of hybrid poplar.
Biotechnology for biofuels
Aditya Bhalla, Namita Bansal, Ryan J Stoklosa, Mackenzie Fountain, John Ralph, David B Hodge, Eric L Hegg
Affiliations
Affiliations
- DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, USA ; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, USA.
- DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, USA ; Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, USA.
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, USA.
- DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, USA.
- DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, USA ; Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, USA ; Division of Sustainable Process Engineering, Luleå University of Technology, Luleå, Sweden.
PMID: 26862348
PMCID: PMC4746924 DOI: 10.1186/s13068-016-0442-0
Abstract
BACKGROUND: Strategies to improve copper-catalyzed alkaline hydrogen peroxide (Cu-AHP) pretreatment of hybrid poplar were investigated. These improvements included a combination of increasing hydrolysis yields, while simultaneously decreasing process inputs through (i) more efficient utilization of H2O2 and (ii) the addition of an alkaline extraction step prior to the metal-catalyzed AHP pretreatment. We hypothesized that utilizing this improved process could substantially lower the chemical inputs needed during pretreatment.
RESULTS: Hybrid poplar was pretreated utilizing a modified process in which an alkaline extraction step was incorporated prior to the Cu-AHP treatment step and H2O2 was added batch-wise over the course of 10 h. Our results revealed that the alkaline pre-extraction step improved both lignin and xylan solubilization, which ultimately led to improved glucose (86 %) and xylose (95 %) yields following enzymatic hydrolysis. An increase in the lignin solubilization was also observed with fed-batch H2O2 addition relative to batch-only addition, which again resulted in increased glucose and xylose yields (77 and 93 % versus 63 and 74 %, respectively). Importantly, combining these strategies led to significantly improved sugar yields (96 % glucose and 94 % xylose) following enzymatic hydrolysis. In addition, we found that we could substantially lower the chemical inputs (enzyme, H2O2, and catalyst), while still maintaining high product yields utilizing the improved Cu-AHP process. This pretreatment also provided a relatively pure lignin stream consisting of ≥90 % Klason lignin and only 3 % xylan and 2 % ash following precipitation. Two-dimensional heteronuclear single-quantum coherence (2D HSQC) NMR and size-exclusion chromatography demonstrated that the solubilized lignin was high molecular weight (Mw ≈ 22,000 Da) and only slightly oxidized relative to lignin from untreated poplar.
CONCLUSIONS: This study demonstrated that the fed-batch, two-stage Cu-AHP pretreatment process was effective in pretreating hybrid poplar for its conversion into fermentable sugars. Results showed sugar yields near the theoretical maximum were achieved from enzymatically hydrolyzed hybrid poplar by incorporating an alkaline extraction step prior to pretreatment and by efficiently utilizing H2O2 during the Cu-AHP process. Significantly, this study reports high sugar yields from woody biomass treated with an AHP pretreatment under mild reaction conditions.
Keywords: Alkaline hydrogen peroxide (AHP) pretreatment; Biomass conversion; Catalysis; Cellulosic biofuels; Copper; Hybrid poplar; Lignin; Oxidative delignification; Sugars
References
- Biotechnol J. 2015 Apr;10(4):510-24 - PubMed
- Biotechnol Biofuels. 2013 Jan 28;6(1):10 - PubMed
- Biotechnol Biofuels. 2014 Apr 03;7(1):48 - PubMed
- Proc Natl Acad Sci U S A. 2011 Mar 1;108(9):3803-8 - PubMed
- Bioresour Technol. 2010 Apr;101(8):2782-92 - PubMed
- Bioresour Technol. 2013 Dec;150:321-7 - PubMed
- Biotechnol Bioeng. 2015 Feb;112(2):252-62 - PubMed
- Bioresour Technol. 2003 May;87(3):255-61 - PubMed
- J Am Chem Soc. 2002 Mar 27;124(12):3026-35 - PubMed
- Science. 2007 Feb 9;315(5813):804-7 - PubMed
- Bioresour Technol. 2012 Sep;119:174-80 - PubMed
- Biotechnol Biofuels. 2014 May 23;7:76 - PubMed
- Biotechnol Bioeng. 1985 Mar;27(3):225-31 - PubMed
- Biotechnol Biofuels. 2014 Jun 10;7:87 - PubMed
- Appl Biochem Biotechnol. 2011 Oct;165(3-4):832-44 - PubMed
- Bioresour Technol. 2013 May;135:109-15 - PubMed
- Bioresour Technol. 2015 Mar;179:467-72 - PubMed
- Bioresour Technol. 2014 Sep;167:530-8 - PubMed
- Bioresour Technol. 2001 Sep;79(2):113-20 - PubMed
- Bioresour Technol. 2011 Oct;102(19):9083-9 - PubMed
- Biotechnol Biofuels. 2011 Jun 09;4(1):16 - PubMed
- Biotechnol Biofuels. 2013 May 09;6(1):75 - PubMed
- Biotechnol Bioeng. 2012 Apr;109(4):922-31 - PubMed
- Proc Natl Acad Sci U S A. 2014 Aug 19;111(33):12013-8 - PubMed
- Biotechnol Adv. 2011 Nov-Dec;29(6):675-85 - PubMed
- Science. 2014 May 16;344(6185):1246843 - PubMed
- Biotechnol Bioeng. 1984 Jun;26(6):628-31 - PubMed
- Bioresour Technol. 2015 Jun;186:223-31 - PubMed
- Biotechnol Bioeng. 2015 Apr;112(4):677-87 - PubMed
- Biotechnol Bioeng. 2013 Apr;110(4):1078-86 - PubMed
- Biotechnol Bioeng. 1984 Jan;26(1):46-52 - PubMed
- Biotechnol Bioeng. 2011 Oct;108(10):2300-11 - PubMed
- Nat Biotechnol. 2008 Feb;26(2):169-72 - PubMed
- Biotechnol Biofuels. 2012 Jun 06;5(1):38 - PubMed
- Biotechnol Bioeng. 2012 Apr;109(4):1083-7 - PubMed
- Biotechnol Biofuels. 2015 Aug 20;8:123 - PubMed
- Bioresour Technol. 2014 Jul;164:292-8 - PubMed
- Bioresour Technol. 2013 Sep;144:429-34 - PubMed
- Bioresour Technol. 2013 Jul;139:249-56 - PubMed
- Biotechnol Biofuels. 2013 Aug 26;6(1):119 - PubMed
- C R Biol. 2004 May;327(5):455-65 - PubMed
- Bioresour Technol. 2005 Apr;96(6):673-86 - PubMed
- Biotechnol Biofuels. 2014 May 13;7:71 - PubMed
Publication Types