Dataset Information

A rapid thioacidolysis method for biomass lignin composition and tricin analysis.

ABSTRACT:

Background

Biomass composition varies from plant to plant and greatly affects biomass utilization. Lignin is a heterogeneous phenolic polymer derived mainly from p-coumaryl, coniferyl, and sinapyl alcohols and makes up to 10-25% of lignocellulosic biomass. Recently, tricin, an O-methylated flavone, was identified as a lignin monomer in many grass species. Tricin may function as a nucleation site for lignification and is advocated as a novel target for lignin engineering to reduce lignin content and improve biomass digestibility in grasses. Thioacidolysis is an analytical method that can be adapted to analyze both lignin monomeric composition and tricin content in the lignin polymer. However, the original thioacidolysis procedure is complex, laborious, and time consuming, making it difficult to be adopted for large-scale screening in biomass research. In this study, a modified, rapid higher throughput thioacidolysis method was developed.

Results

In combination with gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS), the modified thioacidolysis method can be used to simultaneously characterize the lignin composition and tricin content using 2-5 mg of dry samples. The modified method eliminates the solvent extraction and drastically improves the throughput; 80 samples can be processed in one day per person. Our results indicate that there is no significant difference in the determination of lignin S/G ratio and tricin content between the original and modified methods.

Conclusions

A modified thioacidolysis protocol was established. The results demonstrate that the modified method can be used for rapid, high-throughput, and reliable lignin composition and tricin content analyses for screening transgenic plants for cell wall modifications or in large-scale genome-wide association studies (GWAS).

SUBMITTER: Chen F

PROVIDER: S-EPMC7798261 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

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Publications

A rapid thioacidolysis method for biomass lignin composition and tricin analysis.

Chen Fang F Zhuo Chunliu C Xiao Xirong X Pendergast Thomas H TH Devos Katrien M KM

Biotechnology for biofuels 20210111 1

<h4>Background</h4>Biomass composition varies from plant to plant and greatly affects biomass utilization. Lignin is a heterogeneous phenolic polymer derived mainly from p-coumaryl, coniferyl, and sinapyl alcohols and makes up to 10-25% of lignocellulosic biomass. Recently, tricin, an O-methylated flavone, was identified as a lignin monomer in many grass species. Tricin may function as a nucleation site for lignification and is advocated as a novel target for lignin engineering to reduce lignin ...[more]

PMID: 33430954

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Project description:Recent studies demonstrate that several polyphenolic compounds produced from beyond the canonical monolignol biosynthetic pathways can behave as lignin monomers, participating in radical coupling reactions and being incorporated into lignin polymers. Here, we show various classes of flavonoids, the chalconoid naringenin chalcone, the flavanones naringenin and dihydrotricin, and the flavone tricin, incorporated into the lignin polymer of papyrus (Cyperus papyrus L.) rind. These flavonoids were released from the rind lignin by Derivatization Followed by Reductive Cleavage (DFRC), a chemical degradative method that cleaves the β-ether linkages, indicating that at least a fraction of each was integrated into the lignin as β-ether-linked structures. Due to the particular structure of tricin and dihydrotricin, whose C-3' and C-5' positions at their B-rings are occupied by methoxy groups, these compounds can only be incorporated into the lignin through 4'-O-β bonds. However, naringenin chalcone and naringenin have no substituents at these positions and can therefore form additional carbon-carbon linkages, including 3'- or 5'-β linkages that form phenylcoumaran structures not susceptible to cleavage by DFRC. Furthermore, Nuclear Magnetic Resonance analysis indicated that naringenin chalcone can also form additional linkages through its conjugated double bond. The discovery expands the range of flavonoids incorporated into natural lignins, further broadens the traditional definition of lignin, and enhances the premise that any phenolic compound present at the cell wall during lignification could be oxidized and potentially integrated into the lignin structure, depending only on its chemical compatibility. This study indicates that papyrus lignin has a unique structure, as it is the only lignin known to date that integrates such a diversity of phenolic compounds from different classes of flavonoids. This discovery will open up new ways to engineer and design lignins with specific properties and for enhanced value.

Project description:New environmentally sound technologies are needed to derive valuable compounds from renewable resources. Lignin, an abundant polymer in terrestrial plants comprised predominantly of guaiacyl and syringyl monoaromatic phenylpropanoid units, is a potential natural source of aromatic compounds. In addition, the plant secondary metabolite tricin is a recently discovered and moderately abundant flavonoid in grasses. The most prevalent interunit linkage between guaiacyl, syringyl, and tricin units is the β-ether linkage. Previous studies have shown that bacterial β-etherase pathway enzymes catalyze glutathione-dependent cleavage of β-ether bonds in dimeric β-ether lignin model compounds. To date, however, it remains unclear whether the known β-etherase enzymes are active on lignin polymers. Here we report on enzymes that catalyze β-ether cleavage from bona fide lignin, under conditions that recycle the cosubstrates NAD+ and glutathione. Guaiacyl, syringyl, and tricin derivatives were identified as reaction products when different model compounds or lignin fractions were used as substrates. These results demonstrate an in vitro enzymatic system that can recycle cosubstrates while releasing aromatic monomers from model compounds as well as natural and engineered lignin oligomers. These findings can improve the ability to produce valuable aromatic compounds from a renewable resource like lignin.IMPORTANCE Many bacteria are predicted to contain enzymes that could convert renewable carbon sources into substitutes for compounds that are derived from petroleum. The β-etherase pathway present in sphingomonad bacteria could cleave the abundant β-O-4-aryl ether bonds in plant lignin, releasing a biobased source of aromatic compounds for the chemical industry. However, the activity of these enzymes on the complex aromatic oligomers found in plant lignin is unknown. Here we demonstrate biodegradation of lignin polymers using a minimal set of β-etherase pathway enzymes, the ability to recycle needed cofactors (glutathione and NAD+) in vitro, and the release of guaiacyl, syringyl, and tricin as depolymerized products from lignin. These observations provide critical evidence for the use and future optimization of these bacterial β-etherase pathway enzymes for industrial-level biotechnological applications designed to derive high-value monomeric aromatic compounds from lignin.

Project description:BackgroundHigh-throughput evaluation of lignocellulosic biomass feedstock quality is the key to the successful commercialization of bioethanol production. Currently, wet chemical methods for the determination of chemical composition and biomass digestibility are expensive and time-consuming, thus hindering comprehensive feedstock quality assessments based on these biomass specifications. To find the ideal bioethanol feedstock, we perform a near-infrared spectroscopic (NIRS) assay to rapidly and comprehensively analyze the chemical composition and biomass digestibility of 59 Jerusalem artichoke (Helianthus tuberosus L., abbreviated JA) clones collected from 24 provinces in six regions of China.ResultsThe distinct geographical distribution of JA accessions generated varied chemical composition as well as related biomass digestibility (after soluble sugars extraction and mild alkali pretreatment). Notably, the soluble sugars, cellulose, hemicellulose, lignin, ash, and released hexoses, pentoses, and total carbohydrates were rapidly and perfectly predicted by partial least squares regression coupled with model population analyses (MPA), which exhibited significantly higher predictive performance than controls. Subsequently, grey relational grade analysis was employed to correlate chemical composition and biomass digestibility with feedstock quality score (FQS), resulting in the assignment of tested JA clones to five feedstock quality grades (FQGs). Ultimately, the FQGs of JA clones were successfully classified using partial least squares-discriminant analysis model coupled with MPA, attaining a significantly higher correct rate of 97.8% in the calibration subset and 91.1% in the validation subset.ConclusionsBased on the diversity of JA clones, the present study has not only rapidly and precisely examined the biomass composition and digestibility with MPA-optimized NIRS models but has also selected the ideal JA clones according to FQS. This method provides a new insight into the selection of ideal bioethanol feedstock for high-efficiency bioethanol production.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1335-1) contains supplementary material, which is available to authorized users.

Dataset Information

A rapid thioacidolysis method for biomass lignin composition and tricin analysis.

Background

Results

Conclusions

Publications

A rapid thioacidolysis method for biomass lignin composition and tricin analysis.

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