Structural Characterization of Lignin in Wild-Type versus COMT Down-Regulated Switchgrass

Ragauskas, Arthur J.; Pu, Yunqiao; Samuel, Reichel; Jiang, Nan; Fu, Chunxiang; Wang, Zeng‐Yu

doi:10.3389/fenrg.2013.00014

Cited by 25 publications

(41 citation statements)

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Section: Lignin and Its Derivativesmentioning

confidence: 99%

“…Once incorporated into the lignin polymer, these monomers form guaiacyl, syringyl, and p-hydroxyphenyl lignin subunits. The lignin macromolecule is primarily linked via ether bonds and carbon-carbon bonds among phenylpropanoid units (Samuel et al 2014).Lignin is degraded during pulp and paper production to a variety of high, medium, and low molecular weight chlorinated and non-chlorinated fractions (McKague 1981). In particular, the HMW lignin compounds are not effectively degraded during conventional effluent treatment, and the majority of such compounds in wastewater may be discharged into receiving waters (Hyötyläinen and Knuutinen 1993).…”

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confidence: 99%

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Wastewater Treatment and Reclamation: A Review of Pulp and Paper Industry Practices and Opportunities

Hubbe

Metts

Hermosilla

et al. 2016

BioRes

194

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The pulp and paper (P&P) industry worldwide has achieved substantial progress in treating both process water and wastewater, thus limiting the discharge of pollutants to receiving waters. This review covers a variety of wastewater treatment methods, which provide P&P companies with costeffective ways to limit the release of biological or chemical oxygen demand, toxicity, solids, color, and other indicators of pollutant load. Conventional wastewater treatment systems, often comprising primary clarification followed by activated sludge processes, have been widely implemented in the P&P industry. Higher levels of pollutant removal can be achieved by supplementary treatments, which can include anaerobic biological stages, advanced oxidation processes, bioreactors, and membrane filtration technologies. Improvements in the performance of wastewater treatment operations often can be achieved by effective measurement technologies and by strategic addition of agents including coagulants, flocculants, filter aids, and optimized fungal or bacterial cultures. In addition, P&P mills can implement upstream process changes, including dissolved-air-flotation (DAF) systems, filtration save-alls, and kidney-like operations to purify process waters, thus reducing the load of pollutants and the volume of effluent being discharged to end-of-pipe wastewater treatment plants. Keywords: Wastewater treatment; Pulp and paper manufacturing; Advanced oxidation; Membrane technologies; Clarification; Activated sludgeContact information: a: North Carolina State University, Dept. of Forest Biomaterials, Campus Box 8005, Raleigh, NC 29695-8005; b: WestRock Company, Water and Waste Treatment, 600 S 8th St, Fernandina Beach, FL 32034; c: Department of Agricultural and Forestry Engineering, University of Valladolid, Campus Duques de Soria, E-42004 Soria, Spain; d: Complutense University of Madrid, Department of Chemical Engineering, Ingn. Quim, Facultad de Ciencias Químicas, Ciudad Universitaria s/n,S-N, E-28040 Madrid, Spain; e: Concordia University, Dept. Bldg. Civil & Environm. Engn., 1455 Maisonneuve Blvd, West Montreal, PQ H3G 1M8, Canada; f: University of Jyväskylä, Dept. Chem., Box 35, FI-40014 Jyväskylä, Finland; g: Department of Biology, Center for Environmental and Marine Studies, CESAM, University of Aveiro, 3810-193 Aveiro, Portugal; h: Department of Environment and Planning, Center for Environmental and Marine Studies, CESAM, Aveiro & Department of Materials and Ceramics, Institute of Materials, CICECO, University of Aveiro, 3810-193 Aveiro, Portugal; i: FPInnovations, 570 St. Jean Blvd., Pointe Claire, PQ H9R 3J9, Canada; * Corresponding author: hubbe@ncsu.edu Contents of the Article INTRODUCTIONThe pulp and paper (P&P) industry occupies a challenging position with respect to the natural environment. On the positive side, the industry is based on the usage of renewable, photosynthetic resources. On the other hand, the industry discharges huge quantities of aqueous effluents. Large volumes (up to 70 m 3 ) of wastewater ...

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Section: Lignin and Its Derivativesmentioning

confidence: 99%

mentioning

confidence: 99%

Wastewater Treatment and Reclamation: A Review of Pulp and Paper Industry Practices and Opportunities

Hubbe

Metts

Hermosilla

et al. 2016

BioRes

194

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show abstract

“…The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the residual lignin were measured by GPC after acetylation (Samuel et al, 2014). An Ultimate 3000 HPLC system (Dionex Corporation, Sunnyvale, CA, USA) equipped with an ultra violet (UV) detector was used.…”

Section: Gel Permeation Chromatographic (Gpc) Analysismentioning

confidence: 99%

Catalytic Oxidation and Depolymerization of Lignin in Aqueous Ionic Liquid

Das

Shi

2017

Front. Energy Res.

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Lignin is an integral part of the plant cell wall, which provides rigidity to plants, also contributes to the recalcitrance of the lignocellulosic biomass to biochemical and biological deconstruction. Lignin is a promising renewable feedstock for aromatic chemicals; however, an efficient and economic lignin depolymerization method needs to be developed to enable the conversion. In this study, we investigated the depolymerization of alkaline lignin in aqueous 1-ethyl-3-methylimidazolium acetate [C2C1Im][OAc] under oxidizing conditions. Seven different transition metal catalysts were screened in presence of H2O2 as oxidizing agent in a batch reactor. CoCl2 and Nb2O5 proved to be the most effective catalysts in degrading lignin to aromatic compounds. A central composite design was used to optimize the catalyst loading, H2O2 concentration, and temperature for product formation. Results show that lignin was depolymerized, and the major degradation products found in the extracted oil were guaiacol, syringol, vanillin, acetovanillone, and homovanillic acid. Lignin streams were characterized by Fourier transform infrared spectroscopy and gel permeation chromatography to determine effects of the experimental parameters on lignin depolymerization. The weight-average molecular weight (Mw) of liquid stream lignin after oxidation, for CoCl2 and Nb2O5 catalysts were 1,202 and 1,520 g mol, respectively, lower than that of Kraft lignin. Polydispersity index of the liquid stream lignin increased as compared with Kraft lignin, indicating wide span of the molecular weight distribution as a result of lignin depolymerization. Results from this study provide insights into the role of oxidant and transition metal catalysts and the oxidative degradation reaction sequence of lignin toward product formation in presence of aqueous ionic liquid.

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“…RNAi downregulation of COMT expression in canola [28], alfalfa [12, 13], switchgrass [4, 29, 30], and sugarcane [31, 32] consistently resulted in decreases in S monomers, as well as an overall decrease in total lignin content. Similar results have been found after sense or antisense downregulation of COMT in alfalfa [14, 23, 33, 34], poplar [35], tobacco [20], and maize [36, 37].…”

Section: Introductionmentioning

confidence: 99%

RNAi downregulation of three key lignin genes in sugarcane improves glucose release without reduction in sugar production

Bewg

Poovaiah

Lan

et al. 2016

Biotechnol Biofuels

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BackgroundSugarcane is a subtropical crop that produces large amounts of biomass annually. It is a key agricultural crop in many countries for the production of sugar and other products. Residual bagasse following sucrose extraction is currently underutilized and it has potential as a carbohydrate source for the production of biofuels. As with all lignocellulosic crops, lignin acts as a barrier to accessing the polysaccharides, and as such, is the focus of transgenic efforts. In this study, we used RNAi to individually reduce the expression of three key genes in the lignin biosynthetic pathway in sugarcane. These genes, caffeoyl-CoA O-methyltransferase (CCoAOMT), ferulate 5-hydroxylase (F5H) and caffeic acid O-methyltransferase (COMT), impact lignin content and/or composition.ResultsFor each RNAi construct, we selected three events for further analysis based on qRT-PCR results. For the CCoAOMT lines, there were no lines with a reduction in lignin content and only one line showed improved glucose release. For F5H, no lines had reduced lignin, but one line had a significant increase in glucose release. For COMT, one line had reduced lignin content, and this line and another released higher levels of glucose during enzymatic hydrolysis. Two of the lines with improved glucose release (F5H-2 and COMT-2) also had reduced S:G ratios.ConclusionsAlong with improvements in bagasse quality for the production of lignocellulosic-based fuels, there was only one line with reduction in juice sucrose extraction, and three lines with significantly improved sucrose production, providing evidence that the alteration of sugarcane for improved lignocellulosic ethanol production can be achieved without negatively impacting sugar production and perhaps even enhancing it.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0683-y) contains supplementary material, which is available to authorized users.

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Structural Characterization of Lignin in Wild-Type versus COMT Down-Regulated Switchgrass

Cited by 25 publications

References 54 publications

Wastewater Treatment and Reclamation: A Review of Pulp and Paper Industry Practices and Opportunities

Wastewater Treatment and Reclamation: A Review of Pulp and Paper Industry Practices and Opportunities

Catalytic Oxidation and Depolymerization of Lignin in Aqueous Ionic Liquid

RNAi downregulation of three key lignin genes in sugarcane improves glucose release without reduction in sugar production

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