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Valorization of Delonix regia Pods for Bioethanol Production. FERMENTATION-BASEL 2023. [DOI: 10.3390/fermentation9030289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
Delonix regia (common name: Flame tree) pods, an inexpensive lignocellulosic waste matrix, were successfully used to produce value-added bioethanol. Initially, the potentiality of D. regia pods as a lignocellulosic biomass was assessed by Fourier-transform infrared spectroscopy (FTIR), which revealed the presence of several functional groups belonging to cellulose, hemicellulose, and lignin, implying that D. regia pods could serve as an excellent lignocellulosic biomass. Response Surface Methodology (RSM) and Central Composite Design (CCD) were used to optimize pretreatment conditions of incubation time (10–70 min), H2SO4 concentration (0.5–3%), amount of substrate (0.02–0.22 g), and temperature (45–100 °C). Then, RSM-suggested 30 trials of pretreatment conditions experimented in the laboratory, and a trial using 0.16 g substrate, 3% H2SO4, 70 min incubation at 90 °C, yielded the highest amount of glucose (0.296 mg·mL−1), and xylose (0.477 mg·mL−1). Subsequently, the same trial conditions were chosen in the downstream process, and pretreated D. regia pods were subjected to enzymatic hydrolysis with 5 mL of indigenously produced cellulase enzyme (74 filter per unit [FPU]) at 50 °C for 72 h to augment the yield of fermentable sugars, yielding up to 55.57 mg·mL−1 of glucose. Finally, the released sugars were fermented to ethanol by Saccharomyces cerevisiae, yielding a maximum of 7.771% ethanol after 72 h of incubation at 30 °C. Conclusively, this study entails the successful valorization of D. regia pods for bioethanol production.
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Yu O, Yoo CG, Kim CS, Kim KH. Understanding the Effects of Ethylene Glycol-Assisted Biomass Fractionation Parameters on Lignin Characteristics Using a Full Factorial Design and Computational Modeling. ACS OMEGA 2019; 4:16103-16110. [PMID: 31592478 PMCID: PMC6777291 DOI: 10.1021/acsomega.9b02298] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 09/05/2019] [Indexed: 05/16/2023]
Abstract
Contributing to recent lignin valorization efforts, this study uses an integrative approach to explore the effects of fractionation parameters on lignin characteristics. The following reaction parameters are explored: water content of the water-organic solvent mixture, reaction temperature, and sulfuric acid content. Ethylene glycol (EG) was selected as the fractionation solvent because of its promising lignin solubility and extractability. This study takes a novel approach in conducting EG-assisted biomass fractionation; instead of removing lignin from the biomass, lignin was extracted and characterized. Lignin characteristics involving recovery and linkages were analyzed. A maximum of 27 wt % lignin recovery was achieved at a low water content (25%) and high reaction temperature (180 °C) in the presence of sulfuric acid (1 wt %). From NMR analysis, aryl-ether linkages, which are important to preserve for lignin valorization, were decomposed as a result of relatively high temperature and the presence of sulfuric acid. Statistical analysis showed that all individual parameters and their interactions had significant effects on lignin recovery. Computational analysis revealed that hydrogen bonding between the EG and lignin macromolecules greatly decreased with an increasing amount of water.
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Affiliation(s)
- Osbert Yu
- Department
of Chemical and Biological Engineering and Department of Wood Science, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Chang Geun Yoo
- Department
of Paper and Bioprocess Engineering, State
University of New York-College of Environmental Science and Forestry, Syracuse, New York 13210, United States
| | - Chang Soo Kim
- Department
of Chemical and Biological Engineering and Department of Wood Science, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Clean
Energy Research Center, Korea Institute
of Science and Technology, Seoul 02792, Republic
of Korea
| | - Kwang Ho Kim
- Department
of Chemical and Biological Engineering and Department of Wood Science, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Clean
Energy Research Center, Korea Institute
of Science and Technology, Seoul 02792, Republic
of Korea
- E-mail:
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3
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Chaturvedi S, Bhattacharya A, Khare SK. Trends in Oil Production from Oleaginous Yeast Using Biomass: Biotechnological Potential and Constraints. APPL BIOCHEM MICRO+ 2018. [DOI: 10.1134/s000368381804004x] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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4
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Saha B, Kennedy G. Mannose and galactose as substrates for production of itaconic acid byAspergillus terreus. Lett Appl Microbiol 2017; 65:527-533. [DOI: 10.1111/lam.12810] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 09/18/2017] [Accepted: 09/23/2017] [Indexed: 12/16/2022]
Affiliation(s)
- B.C. Saha
- Bioenergy Research Unit; National Center for Agricultural Utilization Research; Agricultural Research Service; U.S. Department of Agriculture; Peoria IL USA
| | - G.J. Kennedy
- Bioenergy Research Unit; National Center for Agricultural Utilization Research; Agricultural Research Service; U.S. Department of Agriculture; Peoria IL USA
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5
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Lynam JG, Kumar N, Wong MJ. Deep eutectic solvents' ability to solubilize lignin, cellulose, and hemicellulose; thermal stability; and density. BIORESOURCE TECHNOLOGY 2017; 238:684-689. [PMID: 28494411 DOI: 10.1016/j.biortech.2017.04.079] [Citation(s) in RCA: 127] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/18/2017] [Accepted: 04/19/2017] [Indexed: 05/05/2023]
Abstract
An environmentally-friendly method to separate cellulose and hemicelluloses from lignin in recalcitrant biomass for subsequent conversion is desirable to reduce greenhouse gas generation. Easily-prepared, deep eutectic solvents (DESs) have low volatility, wide liquid range, non-flammability, nontoxicity, biocompatibility, and biodegradability. This study shows the DESs (formic acid:choline chloride, lactic acid:choline chloride, acetic acid:choline chloride, lactic acid:betaine, and lactic acid:proline) to be capable of preferentially dissolving lignin at 60°C. Thermogravimetric analysis show DES to be stable at typical biomass processing temperatures. Pretreating loblolly pine in one DES increased glucose yield after enzymatic hydrolysis to more than seven times that of raw or glycerol-pretreated pine. The density of DES-pretreated biomass was found to be 40% higher than the untreated pine's density.
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Affiliation(s)
- Joan G Lynam
- Department of Chemical Engineering, Louisiana Tech University, P.O. Box 10348, 600 Dan Reneau Drive, Ruston, LA 71272, USA.
| | - Narendra Kumar
- Department of Chemical Engineering, Louisiana Tech University, P.O. Box 10348, 600 Dan Reneau Drive, Ruston, LA 71272, USA
| | - Mark J Wong
- Department of Chemical & Materials Engineering, University of Nevada, Reno, 1664 N. Virginia St., MS0170, Reno, NV 89557, USA
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6
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Suckling ID, Jack MW, Lloyd JA, Murton KD, Newman RH, Stuthridge TR, Torr KM, Vaidya AA. A mild thermomechanical process for the enzymatic conversion of radiata pine into fermentable sugars and lignin. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:61. [PMID: 28293291 PMCID: PMC5345204 DOI: 10.1186/s13068-017-0748-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 03/01/2017] [Indexed: 05/13/2023]
Abstract
BACKGROUND Conversion of softwoods into sustainable fuels and chemicals is important for parts of the world where softwoods are the dominant forest species. While they have high theoretical sugar yields, softwoods are amongst the most recalcitrant feedstocks for enzymatic processes, typically requiring both more severe pretreatment conditions and higher enzyme doses than needed for other lignocellulosic feedstocks. Although a number of processes have been proposed for converting softwoods into sugars suitable for fuel and chemical production, there is still a need for a high-yielding, industrially scalable and cost-effective conversion route. RESULTS We summarise work leading to the development of an efficient process for the enzymatic conversion of radiata pine (Pinus radiata) into wood sugars. The process involves initial pressurised steaming of wood chips under relatively mild conditions (173 °C for 3-72 min) without added acid catalyst. The steamed chips then pass through a compression screw to squeeze out a pressate rich in solubilised hemicelluloses. The pressed chips are disc-refined and wet ball-milled to produce a substrate which is rapidly saccharified using commercially available enzyme cocktails. Adding 0.1% polyethylene glycol during saccharification was found to be particularly effective with these substrates, reducing enzyme usage to acceptable levels, e.g. 5 FPU/g OD substrate. The pressate is separately hydrolysed using acid, providing additional hemicellulose-derived sugars, for an overall sugar yield of 535 kg/ODT chips (76% of theoretical). The total pretreatment energy input is comparable to other processes, with the additional energy for attrition being balanced by a lower thermal energy requirement. This pretreatment strategy produces substrates with low levels of fermentation inhibitors, so the glucose-rich mainline and pressate syrups can be fermented to ethanol without detoxification. The lignin from the process remains comparatively unmodified, as evident from the level of retained β-ether interunit linkages, providing an opportunity for conversion into saleable co-products. CONCLUSIONS This process is an efficient route for the enzymatic conversion of radiata pine, and potentially other softwoods, into a sugar syrup suitable for conversion into fuels and chemicals. Furthermore, the process uses standard equipment that is largely proven at commercial scale, de-risking process scale-up.
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Affiliation(s)
| | - Michael W. Jack
- Scion, 49 Sala St, Rotorua, 3046 New Zealand
- Department of Physics, University of Otago, PO Box 56, Dunedin, 9054 New Zealand
| | | | | | | | - Trevor R. Stuthridge
- Scion, 49 Sala St, Rotorua, 3046 New Zealand
- FP Innovations, 2665 East Mall, Vancouver, BC V6T 1Z4 Canada
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Perras FA, Luo H, Zhang X, Mosier NS, Pruski M, Abu-Omar MM. Atomic-Level Structure Characterization of Biomass Pre- and Post-Lignin Treatment by Dynamic Nuclear Polarization-Enhanced Solid-State NMR. J Phys Chem A 2017; 121:623-630. [PMID: 28026949 DOI: 10.1021/acs.jpca.6b11121] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Lignocellulosic biomass is a promising sustainable feedstock for the production of biofuels, biomaterials, and biospecialty chemicals. However, efficient utilization of biomass has been limited by our poor understanding of its molecular structure. Here, we report a dynamic nuclear polarization (DNP)-enhanced solid-state (SS)NMR study of the molecular structure of biomass, both pre- and postcatalytic treatment. This technique enables the measurement of 2D homonuclear 13C-13C correlation SSNMR spectra under natural abundance, yielding, for the first time, an atomic-level picture of the structure of raw and catalytically treated biomass samples. We foresee that further such experiments could be used to determine structure-function relationships and facilitate the development of more efficient, and chemically targeted, biomass-conversion technologies.
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Affiliation(s)
- Frédéric A Perras
- Ames Laboratory, U.S. Department of Energy , Ames, Iowa 50011, United States
| | - Hao Luo
- Department of Chemistry, School of Chemical Engineering, and the Center for Direct Catalytic Conversion of Biomass to Biofuels (C3Bio), Purdue University , West Lafayette, Indiana 47907, United States
| | - Ximing Zhang
- Laboratory of Renewable Resources Engineering, Department of Agricultural and Biological Engineering, and the Center for Direct Catalytic Conversion of Biomass to Biofuels (C3Bio), Purdue University , West Lafayette, Indiana 47907, United States
| | - Nathan S Mosier
- Laboratory of Renewable Resources Engineering, Department of Agricultural and Biological Engineering, and the Center for Direct Catalytic Conversion of Biomass to Biofuels (C3Bio), Purdue University , West Lafayette, Indiana 47907, United States
| | - Marek Pruski
- Ames Laboratory, U.S. Department of Energy , Ames, Iowa 50011, United States.,Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States
| | - Mahdi M Abu-Omar
- Department of Chemistry, School of Chemical Engineering, and the Center for Direct Catalytic Conversion of Biomass to Biofuels (C3Bio), Purdue University , West Lafayette, Indiana 47907, United States
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8
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Liu Y, Wang J, Wolcott M. Modeling the production of sugar and byproducts from acid bisulfite pretreatment and enzymatic hydrolysis of Douglas-fir. BIORESOURCE TECHNOLOGY 2017; 224:389-396. [PMID: 27806885 DOI: 10.1016/j.biortech.2016.10.071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 10/21/2016] [Accepted: 10/22/2016] [Indexed: 06/06/2023]
Abstract
The aim of this work was to investigate the kinetics of multiple chemicals in acid bisulfite pretreatment and the relationship between total sugar yields and pretreatment factors (temperature and time). The results showed Saeman model accurately fitted the pretreatment process. According to this kinetic model, a maximum hemicellulose hydrolysis yield was achieved at a treatment time of 75min with a temperature of 145°C. Meantime, the concentrations of acetic acid, hydroxymethylfurfural (HMF), and furfural were 1.54, 0.60, and 1.15gL-1, respectively. Also, a Lorentzian function described the relationship between total sugar yield and pretreatment factors: temperature and time. The regression parameters from this mathematical fitting have accurately reflected the maximum total sugar yield and the optimal treatment conditions were determined to be 145°C and 110min.
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Affiliation(s)
- Yalan Liu
- Composite Materials & Engineering Center, Washington State University, Pullman, WA 99164-1806, United States.
| | - Jinwu Wang
- United State Department of Agriculture, Forest Service, Forest Products Laboratory, 35 Flagstaff Road, Orono, ME 04469-5793, United States
| | - Michael Wolcott
- Composite Materials & Engineering Center, Washington State University, Pullman, WA 99164-1806, United States
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Nwaneshiudu IC, Ganguly I, Pierobon F, Bowers T, Eastin I. Environmental assessment of mild bisulfite pretreatment of forest residues into fermentable sugars for biofuel production. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:15. [PMID: 26807148 PMCID: PMC4722614 DOI: 10.1186/s13068-016-0433-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 01/08/2016] [Indexed: 05/24/2023]
Abstract
BACKGROUND Sugar production via pretreatment and enzymatic hydrolysis of cellulosic feedstock, in this case softwood harvest residues, is a critical step in the biochemical conversion pathway towards drop-in biofuels. Mild bisulfite (MBS) pretreatment is an emerging option for the breakdown and subsequent processing of biomass towards fermentable sugars. An environmental assessment of this process is critical to discern its future sustainability in the ever-changing biofuels landscape. RESULTS The subsequent cradle-to-gate assessment of a proposed sugar production facility analyzes sugar made from woody biomass using MBS pretreatment across all seven impact categories (functional unit 1 kg dry mass sugar), with a specific focus on potential global warming and eutrophication impacts. The study found that the eutrophication impact (0.000201 kg N equivalent) is less than the impacts from conventional beet and cane sugars, while the global warming impact (0.353 kg CO2 equivalent) falls within the range of conventional processes. CONCLUSIONS This work discusses some of the environmental impacts of designing and operating a sugar production facility that uses MBS as a method of treating cellulosic forest residuals. The impacts of each unit process in the proposed facility are highlighted. A comparison to other sugar-making process is detailed and will inform the growing biofuels literature.
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Affiliation(s)
- Ikechukwu C. Nwaneshiudu
- Department of the Environment and Forest Sciences, University of Washington, Box 351750, Seattle, WA 98195 1750 USA
| | - Indroneil Ganguly
- Department of the Environment and Forest Sciences, University of Washington, Box 351750, Seattle, WA 98195 1750 USA
| | - Francesca Pierobon
- Department of the Environment and Forest Sciences, University of Washington, Box 351750, Seattle, WA 98195 1750 USA
| | - Tait Bowers
- Department of the Environment and Forest Sciences, University of Washington, Box 351750, Seattle, WA 98195 1750 USA
| | - Ivan Eastin
- Department of the Environment and Forest Sciences, University of Washington, Box 351750, Seattle, WA 98195 1750 USA
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Bhalla A, Bansal N, Stoklosa RJ, Fountain M, Ralph J, Hodge DB, Hegg EL. Effective alkaline metal-catalyzed oxidative delignification of hybrid poplar. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:34. [PMID: 26862348 PMCID: PMC4746924 DOI: 10.1186/s13068-016-0442-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 01/20/2016] [Indexed: 05/11/2023]
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.
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Affiliation(s)
- Aditya Bhalla
- />DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, USA
- />Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, USA
| | - Namita Bansal
- />DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, USA
- />Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, USA
| | - Ryan J. Stoklosa
- />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
| | - Mackenzie Fountain
- />Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, USA
| | - John Ralph
- />DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, USA
| | - David B. Hodge
- />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
| | - Eric L. Hegg
- />DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, USA
- />Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, USA
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Zhu JY, Chandra MS, Gu F, Gleisner R, Reiner R, Sessions J, Marrs G, Gao J, Anderson D. Using sulfite chemistry for robust bioconversion of Douglas-fir forest residue to bioethanol at high titer and lignosulfonate: a pilot-scale evaluation. BIORESOURCE TECHNOLOGY 2015; 179:390-397. [PMID: 25553570 DOI: 10.1016/j.biortech.2014.12.052] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 12/12/2014] [Accepted: 12/13/2014] [Indexed: 05/19/2023]
Abstract
This study demonstrated at the pilot-scale (50 kg) use of Douglas-fir forest harvest residue, an underutilized forest biomass, for the production of high titer and high yield bioethanol using sulfite chemistry without solid-liquor separation and detoxification. Sulfite Pretreatment to Overcome the Recalcitrance of Lignocelluloses (SPORL) was directly applied to the ground forest harvest residue with no further mechanical size reduction, at a low temperature of 145°C and calcium bisulfite or total SO2 loadings of only 6.5 or 6.6 wt% on oven dry forest residue, respectively. The low temperature pretreatment facilitated high solids fermentation of the un-detoxified pretreated whole slurry. An ethanol yield of 282 L/tonne, equivalent to 70% theoretical, with a titer of 42 g/L was achieved. SPORL solubilized approximately 45% of the wood lignin as directly marketable lignosulfonate with properties equivalent to or better than a commercial lignosulfonate, important to improve the economics of biofuel production.
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Affiliation(s)
- J Y Zhu
- USDA Forest Service, Forest Products Lab, Madison, WI, USA.
| | - M Subhosh Chandra
- USDA Forest Service, Forest Products Lab, Madison, WI, USA; Dept. of Microbiology, Yogi Vemana University, Kadapa, India
| | - Feng Gu
- Jiangsu Provincial Key and Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing, China; USDA Forest Service, Forest Products Lab, Madison, WI, USA
| | | | - Rick Reiner
- USDA Forest Service, Forest Products Lab, Madison, WI, USA
| | - John Sessions
- College of Forestry, Oregon State University, Corvallis, OR, USA
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12
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Li Z, Bansal N, Azarpira A, Bhalla A, Chen CH, Ralph J, Hegg EL, Hodge DB. Chemical and structural changes associated with Cu-catalyzed alkaline-oxidative delignification of hybrid poplar. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:123. [PMID: 26300970 PMCID: PMC4546027 DOI: 10.1186/s13068-015-0300-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 07/30/2015] [Indexed: 05/11/2023]
Abstract
BACKGROUND Alkaline hydrogen peroxide pretreatment catalyzed by Cu(II) 2,2'-bipyridine complexes has previously been determined to substantially improve the enzymatic hydrolysis of woody plants including hybrid poplar as a consequence of moderate delignification. In the present work, cell wall morphological and lignin structural changes were characterized for this pretreatment approach to gain insights into pretreatment outcomes and, specifically, to identify the extent and nature of lignin modification. RESULTS Through TEM imaging, this catalytic oxidation process was shown to disrupt cell wall layers in hybrid poplar. Cu-containing nanoparticles, primarily in the Cu(I) oxidation state, co-localized with the disrupted regions, providing indirect evidence of catalytic activity whereby soluble Cu(II) complexes are reduced and precipitated during pretreatment. The concentration of alkali-soluble polymeric and oligomeric lignin was substantially higher for the Cu-catalyzed oxidative pretreatment. This alkali-soluble lignin content increased with time during the catalytic oxidation process, although the molecular weight distributions were unaltered. Yields of aromatic monomers (including phenolic acids and aldehydes) were found to be less than 0.2 % (wt/wt) on lignin. Oxidation of the benzylic alcohol in the lignin side-chain was evident in NMR spectra of the solubilized lignin, whereas minimal changes were observed for the pretreatment-insoluble lignin. CONCLUSIONS These results provide indirect evidence for catalytic activity within the cell wall. The low yields of lignin-derived aromatic monomers, together with the detailed characterization of the pretreatment-soluble and pretreatment-insoluble lignins, indicate that the majority of both lignin pools remained relatively unmodified. As such, the lignins resulting from this process retain features closely resembling native lignins and may, therefore, be amenable to subsequent valorization.
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Affiliation(s)
- Zhenglun Li
- />Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI USA
- />DOE-Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI USA
- />College of Agricultural Sciences, Oregon State University, Corvallis, OR USA
| | - Namita Bansal
- />DOE-Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI USA
- />Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI USA
| | - Ali Azarpira
- />DOE-Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, WI USA
| | - Aditya Bhalla
- />DOE-Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI USA
- />Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI USA
| | - Charles H Chen
- />Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI USA
- />Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD USA
| | - John Ralph
- />DOE-Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, WI USA
- />Department of Biochemistry, University of Wisconsin, Madison, WI USA
| | - Eric L Hegg
- />DOE-Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI USA
- />Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI USA
| | - David B Hodge
- />Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI USA
- />DOE-Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI USA
- />Department of Biosystems and Agricultural Engineering, Michigan State University, East Lansing, WI USA
- />Division of Sustainable Process Engineering, Luleå University of Technology, Luleå, Sweden
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Ohm RA, Riley R, Salamov A, Min B, Choi IG, Grigoriev IV. Genomics of wood-degrading fungi. Fungal Genet Biol 2014; 72:82-90. [DOI: 10.1016/j.fgb.2014.05.001] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 05/08/2014] [Accepted: 05/10/2014] [Indexed: 01/01/2023]
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