Changes in Phenolics Distribution After Chemical Pretreatment and Enzymatic Conversion of Miscanthus × giganteus Internode

Belmokhtar, Nassim; Habrant, Anouck; Ferreira, Nicolas Lopes; Chabbert, Brigitte

doi:10.1007/s12155-012-9275-2

Cited by 22 publications

(25 citation statements)

References 54 publications

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“…Sugar analysis was performed by high-performance anion-exchange chromatography (Dionex DX 500; Thermo Scientific) after a two-step sulfuric acid hydrolysis of CWR using 2 deoxyribose as internal standard (Belmokhtar et al, 2013).…”

Section: Lignin Sugar and Protein Determinationmentioning

confidence: 99%

Ectopic Lignification in the Flax lignified bast fiber1 Mutant Stem Is Associated with Tissue-Specific Modifications in Gene Expression and Cell Wall Composition

et al. 2014

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Histochemical screening of a flax ethyl methanesulfonate population led to the identification of 93 independent M2 mutant families showing ectopic lignification in the secondary cell wall of stem bast fibers. We named this core collection the Linum usitatissimum (flax) lbf mutants for lignified bast fibers and believe that this population represents a novel biological resource for investigating how bast fiber plants regulate lignin biosynthesis. As a proof of concept, we characterized the lbf1 mutant and showed that the lignin content increased by 350% in outer stem tissues containing bast fibers but was unchanged in inner stem tissues containing xylem. Chemical and NMR analyses indicated that bast fiber ectopic lignin was highly condensed and rich in G-units. Liquid chromatography-mass spectrometry profiling showed large modifications in the oligolignol pool of lbf1 innerand outer-stem tissues that could be related to ectopic lignification. Immunological and chemical analyses revealed that lbf1 mutants also showed changes to other cell wall polymers. Whole-genome transcriptomics suggested that ectopic lignification of flax bast fibers could be caused by increased transcript accumulation of (1) the cinnamoyl-CoA reductase, cinnamyl alcohol dehydrogenase, and caffeic acid O-methyltransferase monolignol biosynthesis genes, (2) several lignin-associated peroxidase genes, and (3) genes coding for respiratory burst oxidase homolog NADPH-oxidases necessary to increase H 2 O 2 supply.

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Section: Lignin Sugar and Protein Determinationmentioning

confidence: 99%

Ectopic Lignification in the Flax lignified bast fiber1 Mutant Stem Is Associated with Tissue-Specific Modifications in Gene Expression and Cell Wall Composition

et al. 2014

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“…A generalized linear model (GLM) procedure with Tukey adjustment at 95% confidence level in SAS 9.3 (Cary, NC, USA) was used to statistically analyze experimental data. The main effects were NaOH concentrations (0.5%, 1.0%, and 1.5%) and pretreatment times (15,30, and 60 min) and dependent variables were monomeric sugar production (i.e., glucose, xylose), lignin content including AIL and ASL, and amount of lignin degradation compounds (i.e., Sy, SA, V, VA, Hy, S/G, and H/G) generated.…”

Section: Discussionmentioning

confidence: 99%

“…Switchgrass was pretreated in an autoclave (Model 3021, Amsco, Mentor, OH, USA) at 121 • C with a combination of three NaOH concentrations (0.5%, 1.0%, and 1.5%, w/v) and three pretreatment times (15,30, and 60 min) using a full factorial experimental design based on previous research by our group and others [16][17][18][19]. Five grams of biomass was mixed with 50 mL NaOH solution (10% w/v solid loading, dry basis) in 125 mL serum bottles which were crimp-sealed for pretreatment.…”

Section: Sodium Hydroxide Pretreatmentmentioning

confidence: 99%

“…An estimation of changes in lignin content after NaOH pretreatment showed that higher concentration and longer pretreatment times led to increased delignification (Table 2), with delignification ranging from 44.0% (at 0.5% with 15 min) to 84.6% (at 1.5% NaOH with 30 min). Lignin has cross-ester-linkages with structural carbohydrates, especially hemicelluloses such as arabinoxylan, and it is reported that NaOH comprehensively disrupts these linkages [8,30,31], resulting in the removal of lignin and xylan from the biomass, which further contributes to lower solid recovery.…”

Section: Chemical Composition Of Sodium Hydroxide-pretreated Switchgrassmentioning

confidence: 99%

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Changes in Lignin Chemistry of Switchgrass due to Delignification by Sodium Hydroxide Pretreatment

et al. 2018

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Switchgrass was pretreated with sodium hydroxide (NaOH) at various concentrations and pretreatment times to investigate how delignification caused by NaOH affects its lignin chemistry. NaOH resulted in significant delignification ranging from 44.0 to 84.6% depending on pretreatment intensity. While there was no significant glucan loss due to NaOH pretreatment, higher NaOH concentrations removed xylan by up to 28.3%. Nitrobenzene oxidation (NBO) was used to study changes in lignin chemistry, and indicated that at higher NaOH concentrations, the amount of 4-hydroxygenzaldehyde (Hy) degraded from p-hydroxyphenyl propanol (H) lignin units was significantly reduced (p < 0.05). However, amounts of syringic (SA) and vanillic (VA) acids generated from syringyl (S) and guaiacyl (G) degradation were greater at higher NaOH concentration. S/G ratio (=0.62 raw switchgrass) did not significantly (p > 0.05) change with 15 min pretreatment, but it increased to 0.75 and 0.72, respectively, with 30 and 60 min pretreatments (p < 0.05). Increase in NaOH concentration did not significantly (p > 0.05) change S/G ratio, but H/G ratio (=0.48 raw switchgrass) decreased significantly to 0.14 regardless of pretreatment times. Overall, the H unit was found to be more susceptible to NaOH than S and G unit monolignols. Though changes in lignin chemistry due to NaOH concentration were observed, their impact on cellulolytic enzyme action during hydrolysis could not be fully understood. Further studies on lignin isolation may help to determine how these changes in lignin chemistry by NaOH impact cellulolytic enzymes.

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“…Chemical and structural features limiting enzyme progression in plant cell walls are complex and generally require a multiscale visualization combined to physicochemical characterization to get insights into the changes due to pretreatment [16–18]. Besides chemical and structural characterization of the whole sample, microscopic approaches such as optical microscopy, microspectrophotometry, atomic force microscopy and electron microscopy have provided critical information related to the cell wall modifications caused by both pretreatments and enzyme hydrolysis [19, 20]. Altogether these studies have shown that pretreatments induce the degradation and/or removal of the hemicellulose and lignin, and overall lignocellulose architecture and porosity can be changed drastically [6, 16, 21, 22].…”

Section: Introductionmentioning

confidence: 99%

Exploring accessibility of pretreated poplar cell walls by measuring dynamics of fluorescent probes

Paës

Habrant

Ossemond

et al. 2017

Biotechnol Biofuels

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BackgroundThe lignocellulosic cell wall network is resistant to enzymatic degradation due to the complex chemical and structural features. Pretreatments are thus commonly used to overcome natural recalcitrance of lignocellulose. Characterization of their impact on architecture requires combinatory approaches. However, the accessibility of the lignocellulosic cell walls still needs further insights to provide relevant information.ResultsPoplar specimens were pretreated using different conditions. Chemical, spectral, microscopic and immunolabeling analysis revealed that poplar cell walls were more altered by sodium chlorite-acetic acid and hydrothermal pretreatments but weakly modified by soaking in aqueous ammonium. In order to evaluate the accessibility of the pretreated poplar samples, two fluorescent probes (rhodamine B-isothiocyanate–dextrans of 20 and 70 kDa) were selected, and their mobility was measured by using the fluorescence recovery after photobleaching (FRAP) technique in a full factorial experiment. The mobility of the probes was dependent on the pretreatment type, the cell wall localization (secondary cell wall and cell corner middle lamella) and the probe size. Overall, combinatory analysis of pretreated poplar samples showed that even the partial removal of hemicellulose contributed to facilitate the accessibility to the fluorescent probes. On the contrary, nearly complete removal of lignin was detrimental to accessibility due to the possible cellulose–hemicellulose collapse.ConclusionsEvaluation of plant cell wall accessibility through FRAP measurement brings further insights into the impact of physicochemical pretreatments on lignocellulosic samples in combination with chemical and histochemical analysis. This technique thus represents a relevant approach to better understand the effect of pretreatments on lignocellulose architecture, while considering different limitations as non-specific interactions and enzyme efficiency.

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Changes in Phenolics Distribution After Chemical Pretreatment and Enzymatic Conversion of Miscanthus × giganteus Internode

Cited by 22 publications

References 54 publications

Ectopic Lignification in the Flax lignified bast fiber1 Mutant Stem Is Associated with Tissue-Specific Modifications in Gene Expression and Cell Wall Composition

Ectopic Lignification in the Flax lignified bast fiber1 Mutant Stem Is Associated with Tissue-Specific Modifications in Gene Expression and Cell Wall Composition

Changes in Lignin Chemistry of Switchgrass due to Delignification by Sodium Hydroxide Pretreatment

Exploring accessibility of pretreated poplar cell walls by measuring dynamics of fluorescent probes

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