Search

Co-pyrolysis of lignin and waste plastics, for example polyethylene (PE), has been studied, but related reports are basically on condition optimizations. This study revealed a new perspective on PE-promoted lignin pyrolysis to phenolic monomers with mass transfer and radical explanation. Lignin and PE were first pyrolyzed individually to identify pyrolysis characteristics, pyrolytic products, as well as the suitable co-pyrolysis temperature. Then, co-pyrolysis of blended lignin/PE with various ratios was investigated. Yields of lignin products reached the maximum under lignin/PE ratio of 1:1, but blended approach always inhibited the production of lignin phenols. This resulted from the poor mass transfer and interactions between lignin and PE, in which PE pyrolysates could easily escape from the particle gaps. While in layered approach, PE pyrolysates had to pass through the lignin layer which contributed to the good interactions with lignin pyrolysis intermediates, thus the yields of lignin-derived products were significantly improved. Interactions between lignin and PE (or their pyrolysates) were mainly radical quenching reactions, and X-ray photoelectron spectrum (XPS) and electron paramagnetic resonance (EPR) of pyrolytic chars were conducted to verify these interactions controlled by mass transfer. The percentage of C C (sp2) and concentration of organic stable radicals in layered lignin/PE char were both the lowest compared with those in blended lignin/PE and lignin char, indicating the stabilization of lignin-derived radicals by PE pyrolysates. Moreover, the spin concentration of radicals in the char from layered char/PE was lower than that in lignin char, which further affirmed the quenching of radicals by PE in the layered co-pyrolysis mode.

Here, we report a Ru/TS-1 catalyst for selective hydrogenolysis of guaiacol to benzene in the aqueous phase at conditions of 240 °C and 2 bar H2, achieving a benzene yield of 86% with a hydrogenolysis rate of 103.1 mmol g−1 h−1. It was found that Silicalite-1 (MFI type) with suitable pore sizes supported Ru nanoparticles (NPs) favored for hydrogenolysis of guaiacol, whereas de-aluminated Ru/HBEA, Ru/HY and Ru/MWW (without acidic sites) accelerated the parallel reactions of hydrogenation of aromatics. In addition, Ru NPs located at the orifice of Silicalite-1 was proved to be more electron-deficient and active than Ru NPs on the outer surface, as evidenced by CO-IR characterization and activity tests on Ru/Silicalite-1 (with and without templates). Moreover, Bronsted acid sites (BAS) on Ru/MFI highly promoted the hydrogenation rates of aromatics, while Lewis acid sites (LAS) on Ru/TS-1 and Ru/MFI led to a linear increase of guaiacol hydrogenolysis rate to benzene, probably due to the enhanced absorbance capability of guaiacol and phenol on the LAS of MFI. Thus, pore structure properties of MFI coupled with abundant LAS (TS-1) as well as Ru NPs on the orifice of pores of TS-1 construct a promising catalyst for achieving efficient aromatic hydrocarbons from selective hydrogenolysis of lignin.

As an aromatic polymer in nature, lignin has recently attracted gross attention because of its advantages of high carbon content, low cost and bio-renewability. However, most lignin is directly burnt for power generation to satisfy the energy demand of the pulp mills. As a result, only a handful of isolated lignin is used as a raw material. Thus, increasing value addition on lignin to expand its scope of applications is currently a challenge demanding immediate attention. Many efforts have been made in the valorization of lignin, including the preparation of precursors for carbon fibers. However, its complex structure and diversity significantly restrict the spinnability of lignin. In this review, we provide elaborate knowledge on the preparation of lignin-based carbon fibers ranging from the relationships among chemical structures, formation conditions and properties of fibers, to their potential applications. Specifically, control procedures for different spinning methods of lignin, including melt spinning, solution spinning and electrospinning, together with stabilization and carbonization are deeply discussed to provide an overall understanding towards the formation of lignin-based carbon fibers. We also offer perspectives on the challenges and new directions for future development of lignin-based carbon fibers.

The present work reports the results of the lignin molecule degradation studies using nitrogen-doped ZnO photocatalysts supported on graphene oxide. Three different nitrogen precursors were used to achieve the nitrogen doping in ZnO, namely urea, ethylenediamine, and thiourea, using a microwave-assisted hydrothermal method. Our purpose is to demonstrate that different nitrogen precursors give rise to different amounts of doping in ZnO, which in turn, favorably affects their photocatalytic behavior. The synthesized compounds were tested on the lignin degradation reaction, under visible (Vis) and ultraviolet (UV) energy irradiation. Structural and physicochemical properties of prepared samples were investigated to provide explanation of the photocatalytic behavior observed in samples. XPS analyses were developed to determine differences in nitrogen content, as well to determine the proportion of N-N or O-Z-N binding in samples. Remarkable structural and photocatalytic differences were found for every sample as effect of the nitrogen precursor. Photocatalytic activity tests revealed that the percentage of lignin degradation under UV irradiation was 80 %; while using Vis energy the degradation value was 61 %.

Each year, 50 to 70 million tonnes of lignin are produced worldwide as by-products from pulp industries and biorefineries through numerous processes. Nevertheless, about 98% of lignin is directly burnt to produce steam to generate energy for the pulp mills and only a handful of isolated lignin is used as a raw material for the chemical conversion and for the preparation of various substances as well as modification of lignin into nanomaterials. Thus, thanks to its complex structure, the conversion of lignin to nanolignin, attracting growing attention and generating considerable interest in the scientific community. The objective of this review is to provide a complete understanding and knowledge of the synthesis methods and functionalization of various lignin nanoparticles (LNP). The characterization of LNP such as structural, thermal, molecular weight properties together with macromolecule and quantification assessments are also reviewed. In particular, emerging applications in different areas such as UV barriers, antimicrobials, drug administration, agriculture, anticorrosives, the environment, wood protection, enzymatic immobilization and others were highlighted. In addition, future perspectives and challenges related to the development of LNP are discussed.

Herein, sodium dodecylbenzene sulfonate (SDBS) was used as a template to control the synthesis of Ca0.5Pr0.5FeO3. Its microstructure, composition, and morphology were detected via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The properties of catalyzing bagasse lignin (BL) pyrolysis were determined by thermogravimetric analysis (TG) test and evaluation of a fixed bed alumina microreactor. The results show that the sample Ca0.5Pr0.5FeO3 regulated by SDBS has a cubic crystal phase, and the addition of SDBS does not cause phase transition. Moreover, when the SDBS concentration is 0.10 mol/L, the particle size is 200–500 nm and the specific surface area is 11.26 m2/g. The yields of gas, liquid, and solid products in the BL catalytic pyrolysis are 39.58 wt%, 26.76 wt% and 32.36 wt%, respectively. The contents of CO2 and CO decrease from 54.07% and 4.98% to 45.29% and 3.23%, respectively. The liquid products are mainly guaiacol, syringol, and phenol, and the total selectivity of phenols is 83.67%, accompanied by a small amount of non-aromatic oxygen-containing compounds (five-membered ring (furan) or ester). Compared with the BL pyrolysis and Ca0.5Pr0.5FeO3 catalytic pyrolysis products, the selectivity of guaiacol compounds increases by 43.26%, while those of syringol compounds and phenylketones decrease by 30.08% and 3.39%, respectively. The selectivity of 2,6-dimethoxyphenol is 28.37%. After five catalytic pyrolysis-regeneration cycles, the characteristic peaks of the catalyst do not change significantly and the particles are uniform, suggesting that the catalyst has good crystal phase stability and regeneration stability.

The valorization of lignin is critical to establishing sustainable biorefineries as we transition away from petroleum-derived feedstocks. Advances in lignin fractionation and depolymerization are yielding new opportunities for the biocatalytic upgrading of lignin-derived aromatic compounds (LDACs) using microbial cell factories. Given their roles in lignin metabolism and their catalytic versatility, cytochromes P450 are attractive enzymes in engineering such biocatalysts. Here we highlight P450s that catalyze aromatic O-demethylation, a rate-limiting step in the conversion of LDACs to valuable chemicals, including efforts to engineer the specificity of these enzymes and to use them in developing biocatalysts. We also discuss broader opportunities at the intersection of biochemistry, structure-guided enzyme engineering, and metabolic engineering for application of P450s in the emerging area of microbial lignin valorization.

The demand for high-performance materials is increasing, and most of these materials are petrol based. Therefore, the development of highly efficient and selective catalytic methods that allow access to industrially relevant polymer building blocks from complex biomass depolymerization mixtures is essential. Here, we report on a robust catalytic strategy to obtain the industrially relevant 4,4′-methylenebiscyclohexanamine (MBCA) from lignin oxidation mixtures and its use for constructing fully bio-based polybenzoxazines. The strategy consists of two challenging catalytic steps: 1) the funneling of lignin-derived bisphenol mixtures into 4,4′-methylenebiscyclohexanol (MBC) and 2) the highly selective amination of MBC with ammonia to obtain MBCA. The renewable polybenzoxazines were prepared from MBCA and phenolic lignin platform chemicals. The most promising, cured poly (S-MBCA), shows high glass transition temperature Tg of 315°C, outstanding thermal stability (T10% = 400°C), and good storage modulus (E′25°C = 3.8 GPa), which is competitive with commercial resins.

Lodging is a major problem limiting maize yield worldwide. However, the mechanisms of lodging resistance remain incompletely understood for maize. Here, we evaluated 443 maize accessions for lodging resistance in the field. Five lodging-resistant accessions and five lodging-sensitive accessions were selected for further research. The leaf number, plant height, stem diameter, and rind penetrometer resistance were similar between lodging-resistant and -sensitive inbred lines. The average thickness of sclerenchymatous hypodermis layer was thicker and the vascular area was larger in the lodging-resistant lines compared with lodging-sensitive lines. Although total lignin content in stem tissue did not significantly differ between lodging-resistant and -sensitive lines, phloroglucinol staining revealed that the lignin content of the cell wall in the stem cortex and in the stem vascular tissue near the cortex was higher in the lodging-resistant lines than in the lodging-sensitive lines. Analysis of strand-specific RNA-seq transcriptome showed that a total of 793 genes were up-regulated and 713 genes were down-regulated in lodging-resistant lines relative to lodging-sensitive lines. The up-regulated genes in lodging-resistant lines were enriched in cell wall biogenesis. These results indicated that modification of cell wall biosynthesis would contribute to lodging resistance of maize.

Lignin, the second most plentiful biopolymer, is produced on a large scale as the waste of the pulp and paper industries. Conventionally, lignin is incinerated for energy generation, while less tha...

BACKGROUND Aflatoxin B1 (AFB1 ) is the most dangerous of the mycotoxins that contaminate cereal seeds naturally. A stress lignin formation is linked with the accumulation of reactive oxygen species causing a change in the redox status and formation of stable organic radicals, constituting the first layer of defense. The relationship between AFB1 and changes in lignin organic free radicals in seeds is not known, nor is the part of the seed that is more targeted. Using optical and electron paramagnetic resonance spectroscopy, we investigated AFB1 -induced changes in lignin and organic free radicals in seeds, and whether the inner and outer seed fractions differ in response to increasing AFB1 . RESULTS Different changes in the content of lignin and free radicals with increasing AFB1 concentrations were observed in the two seed fractions. There was a significant positive linear correlation (R = 0.9923, P = 0.00005) between lignin content and AFB1 concentration in the outer fraction, and no correlation between the lignin content and the AFB1 concentration in the inner fraction. We found a positive correlation between the area of the green spectral emission component (C4) and the AFB1 concentration in the outer fraction. CONCLUSIONS To the best of our knowledge, the results showed, for the first time, that maize seed fractions respond differently to aflatoxin with regard to their lignin and organic free radical content. Lignin content and (C4) area may be reliable indicators for the screening of lignin changes against AFB1 content in the seeds, and thus for seed protection capacity. © 2021 Society of Chemical Industry.

Amino-derivatized lignocomposite (ADL-composite) has been designed as an artificial lignin polymer (P1) of monolignol (coniferyl alcohol, CA) enhanced by aniline insertion (P2). The derivatized lignopolymeric (P2) layer covered the surface of a methacrylate particles (SC2/SC6) functionalized previously with amino phenolic crosslinker (p-phenylenediamine (p-Ph-2-NH2) or p-amino-2-hydroxybenzoic acid (p-NH2-SalA)). One-pot biocatalytic approach allowed to combine the preparation of the polymeric materials and also its attachment on the particles surface. Thus, the monolignol (CA) will be oxi-copolymerized together with aniline on the amino pre-functionalized support surface. The oxidation process was performed using H2O2 reagent and catalyzed by peroxidase enzyme (horseradish peroxidase, HRP). The biocatalytic process was evaluated in term of aromatic monomers (CA and aniline) conversion. The chemical structure and properties of the resulted ADL-composites were investigated using specific techniques (e.g. FTIR, TPD, TGA, static contact angle, elemental analysis, and gel permeation chromatography). Attachment of P1/P2 polymer on the particles improved the hydrophobicity and also the basicity of the composite surface. Lipase enzyme was immobilized on the ADL-composites for testing the applicability of ADL-composites for biocatalyst preparation. SEM analysis allowed to notice the modification of ADL-composites surface after enzyme immobilization. Immobilized lipase exhibited better activity compared with free lipase demonstrating the efficiency of ADL-composite as support for enzyme immobilization.

To acclimate to waterlogged conditions, wetland plants form a barrier to radial oxygen loss (ROL) that can enhance oxygen transport to the root apex. We hypothesized that one or more hormones are involved in the induction of the barrier and searched for such hormones in rice. We previously identified 98 genes that were tissue-specifically upregulated during ROL barrier formation in rice. The RiceXPro database showed that most of these genes were highly enhanced by exogenous abscisic acid (ABA). We then examined the effect of ABA on ROL barrier formation by using an ABA biosynthesis inhibitor (fluridone, FLU), by applying exogenous ABA and by examining a mutant with a defective ABA biosynthesis gene (osaba1). FLU suppressed barrier formation in a stagnant solution that mimics waterlogged soil. Under aerobic conditions, rice does not naturally form a barrier, but 24 h of ABA treatment induced barrier formation. osaba1 did not form a barrier under stagnant conditions, but the application of ABA rescued the barrier. In parallel with ROL barrier formation, suberin lamellae formed in the exodermis. These findings strongly suggest that ABA is an inducer of suberin lamellae formation in the exodermis, resulting in an ROL barrier formation in rice.

This paper reports a fresh and robust strategy to develop polyurethane/polysiloxane pressure-sensitive adhesives (PSAs) with excellent properties by replacing part of C5 petroleum resin with modified lignin. A unique aspect of this work is the use of renewable lignin to obtain modified monomers. The phenolic hydroxyl group of lignin is increased by 21.4% after demethylation, which will help to introduce 6-bromo-1-hexene into the lignin structure through Williamson method. The L3 lignin and C5 petroleum resin are mixed with polyurethane/polysiloxane prepolymer, and furthermore a series of PSAs are obtained under ultraviolet light. It turns out that L3 lignin can not only replace part of C5 petroleum resin, but also obtain attractive and controllable features. Especially when the mass ratio of C5 petroleum resin to L3 lignin is 6:4, compared with pure C5 petroleum resin, the 180° peel strength and the shear strength of PU46 are increased by 24.1% and 91.5% respectively. Additionally, the shear strength on the wood substrate is increased by 320.6%. This study provides an effective method for the preparation of high value-added lignin PSA, and expands the application fields of PSA.

The current work studies the reductive catalytic depolymerization (RCD) of lignin from a novel semi-industrial process. The aim was to obtain aromatic mono-, di-, tri-, and tetramers for further valorization. The substrate and products were characterized by multiple analytical methods, including high pressure size-exclusion chromatography (HPSEC), gas chromatography-mass spectrometry, GC-flame ionization detector (FID), GC-FID/thermal conductivity detector (TCD), and NMR. The RCD was studied by exploring the influence of different parameters, such as lignin solubility, reaction time, hydrogen pressure, reaction temperature, pH, type and loading of the catalyst, as well as type and composition of the organic/aqueous solvent. The results show that an elevated temperature, a redox catalyst, and a hydrogen atmosphere are essential for the depolymerization and stability of the products, while the reaction medium also plays an important role. The highest obtained mono- to tetramers yield was 98% and mono- to dimers yield over 85% in the liquid phase products. The reaction mechanisms influenced the structure of the aliphatic chain in the monomers, but left the phenolic structure along with the methoxy groups largely unaltered. The current work contributes to the development and debottlenecking of the novel and sustainable overall process, which utilizes efficiently all the fractions of wood, in line with the principles of green engineering and chemistry.

The extent to which ectomycorrhizal (ECM) fungi decay soil organic matter (SOM) has implications for accurately predicting forest ecosystem response to climate change. Investigating the distribution of gene traits associated with SOM decay among ectomycorrhizal fungal communities could improve understanding of SOM dynamics and plant nutrition. We hypothesized that soil inorganic nitrogen (N) availability structures the distribution of ECM fungal genes associated with SOM decay and, specifically, that ECM fungal communities occurring in inorganic N-poor soils have greater SOM decay potential. To test this hypothesis, we paired amplicon and shotgun metagenomic sequencing of 60 ECM fungal communities associating with Quercus rubra along a natural soil inorganic N gradient. Ectomycorrhizal fungal communities occurring in low inorganic N soils were enriched in gene families involved in the decay of lignin, cellulose, and chitin. Ectomycorrhizal fungal community composition was the strongest driver of shifts in metagenomic estimates of fungal decay potential. Our study simultaneously illuminates the identity of key ECM fungal taxa and gene families potentially involved in the decay of SOM, and we link rhizomorphic and medium-distance hyphal morphologies with enhanced SOM decay potential. Coupled shifts in ECM fungal community composition and community-level decay gene frequencies are consistent with outcomes of trait-mediated community assembly processes.

International audience; The production of H2 via electrolysis seems to be the best alternative to traditional catalytic reforming processes. The electrolysis of lignin allows to produce pure H2 while valorizing a low-price biomass waste with (theoretically) lower energy requirements than water electrolysis. Previous studies were published in the last years dealing with the electro-oxidation of lignin on Ni-based catalysts. Ni is a robust non-expensive metal that presents a wide variety of oxidation states and phase transitions. To this date, it is still not completely clear how these states/transitions activate the lignin molecule. The aim of this study is to get more insights into the cleavage of the main chemical bonds present in the complex lignin structure over different Ni oxidation states. A Ni/C catalyst, prepared by the polyol method, was thoroughly characterized and tested for the electro-oxidation of both, lignin and 2-phenoxyethanol, where the latter is a model molecule representative of the quintessential β-O-4 linkage in lignin.

Alfalfa (Medicago sativa L.) is the most widely cultivated perennial leguminous forage crop woldwide. MicroRNA156 (miR156) precursor genes from dicotyledonous species are reportedly useful for improving alfalfa plant architecture and abiotic stress resistance. However, there has been no report on whether a miR156 precursor gene from a monocotyledonous species functions in alfalfa. We introduced two tandem precursor genes of miR156, rice Osa-MIR156b and Osa-MIR156c (Osa-MIR156bc), into alfalfa. The expression of miR156 in the transgenic (TG) alfalfa was significantly elevated. Compared to wild-type plants, the TG plants overexpressing miR156 had more branches and leaves and showed improved salt and drought tolerance. Overexpression of miR156 slightly reduced plant height, but the biomass yield of TG plants grown in flowerpots was still increased. Forage quality of TG plants was markedly improved by reduction of acid detergent lignin (ADL) content and increase in crude protein content. The expression of the putative miR156 target genes MsSPL6, MsSPL12, and MsSPL13 in TG plants was repressed by miR156 overexpression, and that of all tested MsSPLs would be sharply increased under drought or salt stress. RNA sequencing revealed that overexpression of miR156 affected the expression of genes associated with abiotic stress resistance and plant development in multiple pathways. This first report of overexpression of monocot miR156 precursors in alfalfa sheds light on the function of miRNA156 precursors from the monocot species rice that could be used for genetic improvement of the dicot forage crop alfalfa.

Lightweight, highly strong and bio-based structural materials remain a long-lasting challenge. Here, inspired by nacre, a lightweight and high mechanical performance cellulosic material was fabricated via a facile and effective top-down approach and the resulting material has a high tensile strength of 149.21 MPa and toughness of 1.91 MJ/m3. More specifically, the natural balsawood (NW) was subjected to a simple chemical treatment, removing most lignin and partial hemicellulose, follow by freeze-drying, forming wood aerogel (WA). The delignification process produced many pores and exposed numerous aligned cellulose nanofibers. Afterwards, the WA absorbed a quantity of moisture and was directly densified to form above high-performance cellulosic material. Such treatment imitates highly ordered “brick-and-mortar” arrangement of nacre, in which water molecules plays the role of mortar and cellulose nanofibrils make the brick part. The lightweight and good mechanical properties make this material promising for new energy car, aerospace, etc. This paper also explains the strengthening mechanism for making biomimetic materials by water molecules-induced hydrogen bonding and will open a new path for designing high-performance bio-based structural materials.

Lignin is a potential renewable raw material for synthesis of aromatic molecules and materials. Particularly, Kraft-type lignins are abundantly available as a byproduct of wood and paper industries. Currently, there are practically no valuable products made using this highly complex polymer. Within this work, we have investigated the straightforward, high-yield depolymerization of two different technical lignins (Indulin AT and alkaline lignin) using only a mixture of green short-chain (C-1-C-3) alcohols and water as solvents. As shown here, at a temperature of 220 degrees C, autogenous pressure, and isopropanol/water as a co-solvent medium, it is possible to cleave Kraft lignin without char-forming side reactions. The obtained so-called "light" oil contains guaiacol-based monomeric units of 23 wt % yield together with liquid oligomers of 13 wt % yield combining liquid-liquid and solid-liquid extraction. Two-dimensional nuclear magnetic resonance analysis of lignin residues showed that the isopropanol/water treatment caused a marked breakdown of the intermolecular beta-O-4 and beta-beta bonds; thus, the depolymerization produced monomers and lignin residues with lower molecular weight. The results suggested a synergistic effect between isopropanol and water. No sign of repolymerization reactions could be observed with this process.

Fast pyrolysis of hydrolysis lignin was studied in fluidized bed units. Hydrolysis lignin, a bioproduct from the lignocellulosic ethanol production process (St1 Cellunolix), was processed in bench scale bubbling fluidized bed (BFB) and pilot scale circulating fluidized bed (CFB) units. Utilization of steam and ethanol as hydrogen sources was tested in a BFB unit. Major technical challenges identified were related to slow reaction rates of lignin degradation and the rapid secondary reactions in the vapor phase resulting in deposit formation and pressure buildup in product gas lines. The carbohydrate content of hydrolysis lignin had a clear correlation to its processability. More challenges with clogging and bed agglomeration were observed with lignin feedstock having lower carbohydrate content. The challenges with the bed agglomeration in the BFB unit were overcome by adding a rapidly rotating mixer in the reactor to break the agglomerates. With the CFB unit, bed agglomeration was not a problem, due to high gas velocities and forces applied to sand and lignin particles. In the BFB unit, the screw feeder was cooled and no significant melting problems were observed. In the CFB unit, melting problems were avoided by feeding the raw material in the cold section of reactor. However, severe increases in the pressure buildup and deposit formation rates were observed in both units. Steam and ethanol was tested, separately, in the BFB unit, to provide excess hydrogen in the system. Based on the product analyses both added hydrogen into the system, but hydrogen ended up mostly in the gas phase. To enhance the hydrogen transfer to the organic liquid, a catalyst active in hydrogen transfer is probably needed.

Lignin is an abundant natural feedstock that offers great potential as a renewable substitute for fossil‐based resources. Its polyaromatic structure and unique properties have attracted significant research efforts. The advantages of an enzymatic over chemical or thermal approach to construct or deconstruct lignins are that it operates in mild conditions, requires less energy, and usually uses non‐toxic chemicals. Laccase is a widely investigated oxidative enzyme that can catalyze the polymerization and depolymerization of lignin. Its dual nature causes a challenge in controlling the overall direction of lignin‐laccase catalysis. In this Review, the factors that affect laccase‐catalyzed lignin polymerization were summarized, evaluated, and compared to identify key features that favor lignin polymerization. In addition, a critical assessment of the conditions that enable production of novel lignin hybrids via laccase‐catalyzed grafting was presented. To assess the industrial relevance of laccase‐assisted lignin valorization, patented applications were surveyed and industrial challenges and opportunities were analyzed. Finally, our perspective in realizing the full potential of laccase in building lignin‐based materials for advanced applications was deduced from analysis of the limitations governing laccase‐assisted lignin polymerization and grafting., Laccases as builders: Similar to their role in the formation of lignin in nature, laccases are capable of building advanced lignin‐based materials, given the optimum laboratory conditions. This Review evaluates the factors that affect laccase‐catalyzed lignin polymerization and grafting reactions. Patented applications of lignin‐based materials produced via laccase catalysis are highlighted and potential routes towards unlocking the full capacity of laccase in lignin valorization are proposed.

Lignin is associated with cell wall rigidity, water and solute transport, and resistance to diverse stresses in plants. Lignin consists of polymerized monolignols (p-coumaryl, coniferyl, and sinapyl alcohols), which are synthesized by cinnamyl alcohol dehydrogenase (CAD) in the phenylpropanoid pathway. We previously investigated cold-induced IbCAD1 expression by transcriptome profiling of cold-stored tuberous roots of sweetpotato (Ipomoea batatas [L.] Lam). In this study, we confirmed that IbCAD1 expression levels depended on the sweetpotato root type and were strongly induced by several abiotic stresses. We generated transgenic sweetpotato plants overexpressing IbCAD1 (TC plants) to investigate CAD1 physiological functions in sweetpotato. TC plants displayed lower root weights and lower ratios of tuberous roots to pencil roots than non-transgenic (NT) plants. The lignin contents in tuberous roots of NT and TC plants differed slightly, but these differences were not significant. By contrast, monolignol levels and syringyl (S)/guaiacyl (G) ratios were higher in TC plants than NT plants, primarily owing to syringyl unit accumulation. Tuberous roots of TC plants displayed enhanced low-temperature (4 °C) storage with lower malondialdehyde and H2O2 contents than NT plants. We propose that high monolignol levels in TC tuberous roots served as substrates for increased peroxidase activity, thereby enhancing antioxidation capacity against cold stress–induced reactive oxygen species. Increased monolignol contents and/or increased S/G ratios might contribute to pathogen-induced stress tolerance as a secondary chilling-damage response in sweetpotato. These results provide novel information about CAD1 function in cold stress tolerance and root formation mechanisms in sweetpotato.

White-rot fungi are thought to hold promise for development of a delignification pretreatment process for wood biorefinery that is less energy-consuming than current processes. However, the reaction must take place over weeks and consumes non-neglectable amounts of saccharides. To establish a biological process for wood biorefinery would first require establishment of an enzymatic approach to delignification. Such an approach has the potential to lower costs and reduce saccharide loss. Here, we attempted enzymatic delignification reactions using manganese peroxidases (MnP), a lignin-degrading enzyme, under several reaction conditions. The delignification rate from beech wood meal (particle size45 μm) of up to 11.0% in 48 h was reached in a MnP reaction supplemented with multiple co-oxidants, glucose, glucose oxidase (GOD) and commercial cellulase. An additional 48-h reaction using fresh MnP/co-oxidants increased the delignification rate to 14.2%. Simultaneous enzymatic delignification and saccharification, which occurs without a need for glucose supplementation, successfully improved the glucose yield to 160% of the reaction without MnP. Development of a more accurate imitation of the mechanisms of delignification that occurs in white-rot fungi has the potential to improve the monosaccharide yield resulting from simultaneous delignification and saccharification.

Greening up the chemical industry by using waste biomass streams as feed is a topic of high relevance. Residual lignins from for example the pulp and paper industry and second-generation bioethanol plants are interesting resources for the synthesis of biobased aromatics and alkylphenols. We here report experimental studies on the catalytic hydrotreatment of Kraft lignin to alkylphenols using non-precious metal, sulfur tolerant catalysts in the form of phosphided NiMo catalysts on different supports (AC, SiO2Al2O3, SiO2, MgO-Al2O3, and TiO2) in the absence of an external solvent. The catalysts were prepared by an incipient wetness impregnation method and characterized in detail (BET surface area, SEM, TEM, X-ray diffraction, and temperature-programmed desorption of NH3/CO2). Hydrotreatment experiments were carried out in a batch autoclave at a temperature of 400 °C, for 2 h and 100 bar initial H2 pressure. The lignin oils were analyzed extensively by GPC, GC-MS, GC×GC-FID, and elemental analysis. The highest monomer yield (51.8 wt% on lignin intake) was obtained with the NiMoP catalyst on SiO2 (5.6 wt% Ni, 9.1 wt% Mo and 5.9 wt% P), which is among the best reported in the literature so far. Of the monomers, alkylphenols are the dominant component group (30.6%), followed by aliphatics (8.1%) and aromatics (5.7%). Clear relations between support characteristics and performance were absent. The only exception is the support acidity, and apparently, intermediate acidity is required for best performance. The SiO2-supported NiMoP catalyst was also applied for the hydrotreatment of Lignoboost and Alcell lignin under the same reaction conditions. Whereas Lignoboost gave highly comparable results to Kraft lignin in terms of oil and monomer yield, Alcell lignin gave a considerably lower monomer yield (34.4 wt% on lignin intake). These results are rationalized by considering P/S exchange in the catalyst formulation during the reaction.

Fungal liquefaction of coal is a promising technology to convert low rank coal into value-added products such as humic acids (HAs) that are extensively used as fertilizer. Use of Pakistani Thar lignite for humic acid extraction can promote agriculture industry in Pakistan. In this study, fifty-five fungal strains were isolated from Thar lignite and screened for their lignite solubilization efficiency. Isolates M13 and MI exhibited highest capacity for lignite solubilization and HA was extracted with 67.4 ± 4.3 percent (w/w) yield. Elemental analysis showed increased nitrogen (0.72–1.39 percent) and oxygen (41.7–48 percent), and decreased carbon (51.8–46.1 percent) and sulphur (1.18–0.73 percent) contents in bio-extracted HA (bHA) compared to chemically extracted HA (cHA). UV/Vis spectroscopy showed increased E4/E6 value from 5.6 ± 0.39 (cHA) to 6.28 ± 0.35 (bHA) indicating reduced molecular mass and aromaticity and increased bioactivity of molecule. FTIR analysis also confirmed these results. HPLC analysis of bHA and cHA showed typical choromatogram of humic acids. Enzyme activity staining indicated the presence of fungal cellulase and xylanase on SDS-PAGE gel. The degradation of lignite macromolecules by lignin degrading fungi is a complex process dependent on alkaline substances, chelators, surfactants and extracellular fungal enzymes.

The rapid accumulation of lignin in the cell wall is one of important immune defense mechanism in response to adversity stress in plants. In this study, we found that the enlargement of the root tubers of Rehmannia glutinosa (R. glutinosa) is arrested under consecutive monoculture stress, and this process is accompanied by abnormal accumulation of lignin. Meanwhile, the function of key catalytic enzyme genes in lignin biosynthetic pathway under consecutive monoculture stress was systematically analyzed, of which roles of core genes were validated using reverse genetics. We elucidated that an abnormal deposition of lignin in R. glutinosa roots, induced by consecutive monoculture stress, and arrested the enlargement of root tubers. Additionally, by manipulating the key catalytic enzyme gene RgCCR6, we were able to alter lignin content of roots of R. glutinosa, thereby affecting tuber enlargement. We speculate that cell lignification is an important defense strategy in resistance against consecutive monoculture stress, but the overreacted defense hindered the normal enlargement of root tubers. The findings provide new insights for effectively improving yield reductions of root crops subjected to environmental stress.

The aim of this work was the enhancement of biohydrogen production by an anaerobic bacterial consortium with incorporation of lignin-mediated iron nanoparticles in the fermentation medium. Lignin magnetic nanoparticles (LMNP), identified as magnetite by XRD, exhibited spherical shape and average particle size of 8.6 nm, while lignin non-magnetic nanoparticles (LNMNP) exhibited high agglomeration and an amorphous nature in TEM and XRD, respectively. The fermentation medium (pH 7) was composed of 88% soft drink wastewater (SDW) and 12% corn steep liquor (CSL) and supplemented with NaHCO3 (1.0 g/L) and cysteine-HCl (0.5 g/L). Under optimal conditions, BioH2 production was 17.67 ± 0.54 mL, after 48 h of fermentation at 37 °C. Addition of LMNP and LNMNP increased BioH2 production in 91.0 and 74.3%, respectively. Additionally, 200 mg/L of LMNP and LNMNP in the fermentation medium improved the BioH2 yields (mL H2/g CODremoved) in 2.8- and 2.3-fold, respectively.

Lignin is a major component of plant-derived soil organic matter (SOM) in soils and sediments. Fe-bearing clay minerals are widely distributed in these environments and often co-exist with lignin. While previous studies have reported the electron shuttling and donating roles of certain redox-active SOM in the dissimilatory reduction of structural Fe(III) in Fe-bearing clay minerals, the role of lignin in this process remains unknown. Here we studied this role by incubating an Fe-rich smectite (nontronite NAu-2) with two types of lignin (soluble and insoluble) in the absence and presence of an Fe(III)-reducing bacterium Shewanella putrefaciens CN32 under anaerobic condition. Lactate was added in some experiments as an extra electron donor. The results demonstrated that both soluble and insoluble lignins abiotically reduced structural Fe(III) in NAu-2. The reduction extent was proportional to lignin concentration. After abiotic reaction, lignin served as either electron shuttle or electron donor in the presence of CN32: (1) When lactate was present, lignin served as an electron shuttle to enhance the rate of Fe(III) reduction; (2) When lactate was absent, lignin served as an electron donor for Fe(III) reduction. Although the ultimate biotic Fe(III) reduction extents were similar in the presence of either soluble or insoluble lignin, the reduction rates with soluble lignin were higher than those with insoluble lignin, likely owing to their different electron transfer mechanisms. After interaction with NAu-2 and/or CN32, soluble lignin structure largely remained intact, but with some decreases of humic/fulvic acid-like and protein-like compounds, aromatic functional groups (e.g., C H, C O, COOH), and aliphatic/aromatic compounds. An increase of semiquinone-like organic radicals was observed after lignin interaction with NAu-2. These chemical changes of lignin were likely coupled with the reduction of structural Fe(III) in nontronite. Upon reduction, the nontronite did not display much dissolution and mineral transformation. The findings of this study provide insights into the role of lignin in promoting mineral-microbe interactions and have significant implications for coupled Fe and C biogeochemical cycles in soils and sediments.

Sclerotinia stem rot (SSR) is an economically and globally significant disease in oilseed rape (Brassica napus) caused by the necrotrophic ascomycete Sclerotinia sclerotiorum. This study explored the role of cell wall reinforcement by lignin as a relevant factor for effective plant defense against attack by this pathogen. Expression of key genes in the phenylpropanoid pathway and the induced synthesis of lignin in infected stem tissues were investigated in a study comparing a susceptible (‘Loras’) and a moderately resistant cultivar (‘Zhongyou 821’ [ZY821]). Data revealed an earlier and more rapid defense activation in ZY821 through upregulation of transcript levels of genes related to key steps in the phenylpropanoid pathway associated with increased lignin deposition in the resistant B. napus genotype. Expression level of BnCAD5, encoding a cinnamyl alcohol dehydrogenase, responsible for conversion of monolignol to lignin, was more rapidly upregulated in ZY821 than ‘Loras’. The similar expression pattern of BnCAD5 and the gene BnF5H, encoding for ferulate-5-hydroxylase, which catalyzes the synthesis of syringyl (S) lignin precursors, suggests that BnCAD5 is involved in S lignin formation. Histological observations confirmed these results, showing an earlier increase of S lignin deposition in the infected resistant genotype. Deposition of guaiacyl lignin was detected in both genotypes and is thus considered a component of basal, cultivar-independent defense response of B. napus to stem rot. The results indicate the importance of cell wall modification for quantitative stem rot resistance by responses in the phenylpropanoid metabolism generating distinct lignin types on different temporal scales.

Raman spectroscopy is widely applied in wood science because of its features of being nondestructive, rapidity, and high resolution. However, Raman scattering is weak, and the Raman signal is easily disturbed by autofluorescence arising from endogenous fluorescent molecules in biological tissue. In this work, a sensitive lignin detection platform was fabricated by a composite with a polyaniline (PANI) nanofiber and toluidine blue (TB) under the excitation of visible light. In this platform, TB acts as a specific marker for lignin, and a PANI nanofiber was used as a reinforcing reagent to improve the Raman intensity of TB. When wood slice is impregnated with TB/PANI, the lignin in wood can be precisely labeled with the TB, and the Raman intensity of TB had a threefold increase at 532 nm excitation. This TB/PANI detection platform is expected to make a significant contribution in qualitative and quantitative analysis of lignin to avoid autofluorescence in various lignin-based biosciences.

Wood carbon (C) concentration is a key wood trait that varies widely among tree species, but our understanding of the factors governing this trait is limited, despite reason to hypothesize that wood C varies systematically across environmental gradients. We compiled a novel database of 1145 geo-referenced wood C observations from 415 species, to elucidate climate correlates of wood C concentrations, and test if these relationships differ across tissue types and major taxonomic divisions (i.e. angiosperms vs gymnosperms). Climate variables, including mean annual temperature (MAT) and precipitation and temperature seasonality, are significantly correlated with wood C concentrations. Relationships between wood C and these variables differ across tissue types and taxonomic divisions, yet there is a negative relationship between wood C and MAT that exists across all tissues and species groups. Wood C concentrations in trees are influenced by climate, with experimental evidence (albeit scant) indicating that climate-driven changes in lignin concentrations likely govern these relationships. Our study presents among the first lines of evidence indicating that wood C concentrations are correlated with environmental conditions, thereby enhancing our understanding of the potential adaptive significance of wood C variation in trees.

Authors Alexander Henn, Nina Forsman, and Monika sterberg declare that they have a financial interest in the development and commercialization of the research presented in this article. Aalto University has filed a provisional patent application (FI 20205555). Funding Information: KAH, NF and TZ thank Business Finland for financing via the LignoSphere project (project number: 2117744). This work was also a part of the Academy of Finland's Flagship Programme under projects No. 318890 and 318891 (Competence Center for Materials Bioeconomy, FinnCERES), financial support for KAH. The authors also thank Dr. Heidi Henrickson for her excellent help with proofreading and guidance, Mr. Rob Hindley for his generous help with linguistic support and proofreading, and Valeria Azovskaya for her helpful advice regarding the graphical material. Publisher Copyright: © 2021 The Authors. Published by American Chemical Society. There is a need for safe and sustainable alternatives in the coating industry. Bio-based coatings are interesting in this perspective. Although various oils and waxes have been used as traditional wood coatings, they often lack sufficient durability. Lignin is an abundant natural polyphenol that can be used to cure epoxies, but its poor water solubility has impeded the use of unmodified lignin in coatings in the past. To address this issue, water-dispersible colloidal lignin particles (CLPs) and an epoxy compound, glycerol diglycidyl ether (GDE), were used to prepare multiprotective bio-based surface coatings. With the GDE/CLP ratios of 0.65 and 0.52 g/g, the cured CLP-GDE films became highly resistant to abrasion and heat. When applied as a coating on wooden substrates, the particulate morphology enabled effective protection against water, stains, and sunlight with very thin layers (less than half the weight of commercial coatings) while retaining the wood's breathability excellently. Optimal hydrophobicity was reached with a coat weight of 6.9 g(CLP)/m2, resulting in water contact angle values of up to 120°. Due to their spherical shape and chemical structure, the CLPs acted as both a hardener and a particulate component in the coating, which removed the need for an underlying binding polymer matrix. Light interferometry measurements showed that while commercial polymeric film-forming coatings smoothened the substrate noticeably, the particulate morphology retained the substrate's roughness in lightweight coatings, allowing for a high water contact angle. This work presents new strategies for lignin applications in durable particulate coatings and their advantages compared to both currently used synthetic and bio-based coatings.

The present study reports a sustainable source of lignin, from termite frass. Lignin was extracted using Klason’s method and subjected to polarization studies to check the inhibition efficiency and measured the electrochemical performance of the coated sample on the carbon steel using electrochemical impedance spectroscopy. The anticorrosive property was determined in a simulated corrosive environment (0.1 M NaOH and 0.5 M NaOH). The morphological analysis of the surface of both bare metal and the lignin-coated ones, before and after exposure to the corrosive environment, was recorded using atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy-dispersive X-Ray spectroscopy (EDX). The lignin showed maximum inhibition efficiency at 600 ppm in 0.5 M NaOH solution. Moreover, the lignin coated on carbon steel exhibited about 70% corrosion inhibition efficiency as recorded by potentiodynamic polarization studies and electrochemical impedance spectroscopy. The AFM and SEM analyses further corroborated the protection of the metal surface from corrosion when coated with lignin. Hence, the study suggests lignin from termite frass as a sustainable biological source suitable for anticorrosive applications. Graphic abstract

The growing demand for energy and materials in modern society pushes scientific research to finding new alternative sources to traditional fossil feedstocks. The exploitation of biomass promises to be among the viable alternatives with a lower environmental impact. Making biomass exploitation technologies applicable at an industrial level represents one of the main goals for our society. In this work, the most recent scientific studies concerning the enhancement of lignocellulosic biomasses through the use of deep eutectic solvent (DES) systems have been examined and reported. DESs have an excellent potential for the fractionation of lignocellulosic biomass: the high H-bond capacity and polarity allow the lignin to be deconvolved, making it easier to break down the lignocellulosic complex, producing a free crystallite of cellulose capable of being exploited and valorised. DESs offer valid alternatives of using the potential of lignin (producing aromatics), hemicellulose (achieving furfural) and cellulose (delivering freely degradable substrates through enzymatic transformation into glucose). In this review, the mechanism of DES in the fractionation of lignocellulosic biomass and the main possible uses for the valorisation of lignin, hemicellulose and cellulose were reported, with a critical discussion of the perspectives and limits for industrial application.

In this work, cellulose was extracted from pineapple leaves by basic hydrolysis and surface-modified by silane coupling agent (Si-69) for use as reinforcing agent in polylactic acid (PLA). The pineapple leaves were subjected to alkali and bleaching treatments to remove hemicellulose and lignin. The corresponding FTIR spectra reveals intensity peaks at 1727 cm-1 assigned to C=O stretching in hemicellulose, 1614 cm-1 and 1539 cm-1 from C=C stretching of lignin and 1241 cm-1 attributed to C-O stretching of lignin, all of which decreased following the chemical treatments to confirm the effective removal of hemicellulose and lignin. These results were consistent with fiber composition analysis where hemicellulose and lignin both favorably decreased from approximately 20% to 5.46% and 0.47%, respectively, after chemical treatments. However, cellulose content unfortunately also decreased with bleaching cycles despite improving the cellulose yield. The cellulose was effectively surface-modified by 5 wt% and 10 wt% of Si-69 as confirmed with C-O-Si stretching at 1240 cm-1 from FTIR. As a reinforcing filler to improve PLA performance, cellulose treated by Si-69 were infused into PLA matrix to obtain composite films by solvent casting. As expected, PLA modified with surface-modified cellulose showed the highest value of tensile strength of 21.75 Mpa among the reinforced filler samples and pure PLA, due to a strong adhesion at the interphase of PLA matrix and cellulose.

This research has been carried on to analyze the capability of a new composite to be effectively used as shielding of gamma radiation. The preparation of a metal-organic composite formed by tungsten and Kraft lignin is presented. Samples have been characterized through X-rays and scanning electron microscopy measurements. The results led to the study of the different phase formations. The microscopic analyzes indicate that two different phases are present in the composite. The absence of oxidation in the process even after the temperature treatment imposed to form the sample has also been noticed. Measurements of the attenuation have been performed to study its ability to absorb gamma radiation. A sample of cobalt 60 (Co-60), for which the peak energies are at 1173 keV and 1332 keV, was used as a source of gamma radiation in the experiment of attenuation. The measured attenuation of gamma radiations when the composite is placed to act as a shield is only 16% smaller than the attenuation obtained for standard pure tungsten. This is a clear indication that the new metal-organic composite is suitable for the fabrication of devices dedicated to shielding radiation, with the advantage of being easier to manipulate.

2-Pyrone-4,6-dicarboxylic acid (PDC), a chemically stable intermediate that naturally occurs during microbial degradation of lignin by bacteria, represents a promising building block for diverse biomaterials and polyesters such as biodegradable plastics. The lack of a chemical synthesis method has hindered large-scale utilization of PDC and metabolic engineering approaches for its biosynthesis have recently emerged. In this study, we demonstrate a strategy for the production of PDC via manipulation of the shikimate pathway using plants as green factories. In tobacco leaves, we first showed that transient expression of bacterial feedback-resistant 3-deoxy-D-arabinoheptulosonate 7-phosphate synthase (AroG) and 3-dehydroshikimate dehydratase (QsuB) produced high titers of protocatechuate (PCA), which was in turn efficiently converted into PDC upon co-expression of PCA 4,5-dioxygenase (PmdAB) and 4-carboxy-2-hydroxymuconate-6-semialdehyde dehydrogenase (PmdC) derived from Comamonas testosteroni. We validated that stable expression of AroG in Arabidopsis in a genetic background containing the QsuB gene enhanced PCA content in plant biomass, presumably via an increase of the carbon flux through the shikimate pathway. Further, introducing AroG and the PDC biosynthetic genes (PmdA, PmdB, and PmdC) into the Arabidopsis QsuB background, or introducing the five genes (AroG, QsuB, PmdA, PmdB, and PmdC) stacked on a single construct into wild-type plants, resulted in PDC titers of ~1% and ~3% dry weight in plant biomass, respectively. Consistent with previous studies of plants expressing QsuB, all PDC producing lines showed strong reduction in lignin content in stems. This low lignin trait was accompanied with improvements of biomass saccharification efficiency due to reduced cell wall recalcitrance to enzymatic degradation. Importantly, most transgenic lines showed no reduction in biomass yields. Therefore, we conclude that engineering plants with the proposed de-novo PDC pathway provides an avenue to enrich biomass with a value-added co-product while simultaneously improving biomass quality for the supply of fermentable sugars. Implementing this strategy into bioenergy crops has the potential to support existing microbial fermentation approaches that exploit lignocellulosic biomass feedstocks for PDC production.

Chinese quince is one kind of crop that has edibility and historical medical applications. However, the high amount of lignin makes processing Chinese quince fruit difficult; on the other hand, this lignin represents a valuable resource if a way of using it in industrial applications could be found. In this study, the structural features and antioxidant activities of Brauns native lignin (BNL) isolated from Chinese quince fruit after oven drying (60 °C, 75 °C, and 90 °C), sun drying, freeze-drying, and subcritical dimethyl ether drying were assessed. The BNL samples had low molecular weights (Mw, 2604–5511 g/mol), high carbohydrate content (6.10–9.95 %), and high phenolic OH content (1.76–2.29 mmol/g). NMR spectra showed that the BNL is of the SGH-type with the relative content of p-hydroxyphenyl units ranging from 13 to 21 %. Oven drying (90 °C) reduced the carbohydrate content and increased the phenolic hydroxyl content. Freeze-drying reduced the relative content of β-O-4′ linkages and increased the H-unit content. In terms of antioxidant activities, all samples possessed high DPPH free radical scavenging capacity (IC50, 0.12−0.22 mg/mL) and strong reducing power. These results indicate that BNL extracted from Chinese quince fruit is a promising source of natural antioxidant and biomass material.

The ionoSolv process is one of the most promising technologies for biomass pretreatment in a biorefinery context. In order to evaluate the transition of the ionoSolv pretreatment of biomass from bench-scale experiments to commercial scale, there is a need to get better insight in process intensification. In this work, the effects of biomass loading, particle size, pulp washing protocols and 100-fold scale up for the pretreatment of the grassy biomass Miscanthus giganteus with the IL triethylammonium hydrogen sulfate, [TEA][HSO4], are presented as a necessary step in that direction. At the bench scale, increasing biomass loading from 10 to 50 wt% reduced glucose yields from 68 to 23% due to re-precipitation of lignin onto the pulp surface. Omitting the pulp air-drying step maintained saccharification yields at 66% at 50 wt% loading due to reduced fiber hornification. 100-fold scale-up (from 10 mL to 1 L) improved the efficacy of ionoSolv pretreatment and increasing loadings from 10 to 20 wt% reduced lignin reprecipitation and led to higher glucose yields due to the improved heat and mass transfer caused by efficient slurry mixing in the reactor. Pretreatment of particle sizes of 1–3 mm was more effective than fine powders (0.18–0.85 mm) giving higher glucose yields due to reduced surface area available for lignin re-precipitation while reducing grinding energy needs. Stirred ionoSolv pretreatment showed great potential for industrialization and further process intensification after optimization of the pretreatment conditions (temperature, residence time, stirring speed), particle size and biomass loading. Pulp washing protocols need further improvement to reduce the incidence of lignin precipitation and the water requirements of lignin washing.

Background Xylanase-containing enzyme cocktails are used on an industrial scale to convert xylan into value-added products, as they hydrolyse the β-1,4-glycosidic linkages between xylopyranosyl residues. In the present study, we focused on xynS1, the glycoside hydrolase (GH) 11 xylanase gene derived from the Streptomyces sp. strain J103, which can mediate XynS1 protein synthesis and lignocellulosic material hydrolysis. Results xynS1 has an open reading frame with 693 base pairs that encodes a protein with 230 amino acids. The predicted molecular weight and isoelectric point of the protein were 24.47 kDa and 7.92, respectively. The gene was cloned into the pET-11a expression vector and expressed in Escherichia coli BL21(DE3). Recombinant XynS1 (rXynS1) was purified via His-tag affinity column chromatography. rXynS1 exhibited optimal activity at a pH of 5.0 and temperature of 55 °C. Thermal stability was in the temperature range of 50–55 °C. The estimated Km and Vmax values were 51.4 mg/mL and 898.2 U/mg, respectively. One millimolar of Mn2+ and Na+ ions stimulated the activity of rXynS1 by up to 209% and 122.4%, respectively, and 1 mM Co2+ and Ni2+ acted as inhibitors of the enzyme. The mixture of rXynS1, originates from Streptomyces sp. strain J103 and acetyl xylan esterase (AXE), originating from the marine bacterium Ochrovirga pacifica, enhanced the xylan degradation by 2.27-fold, compared to the activity of rXynS1 alone when Mn2+ was used in the reaction mixture; this reflected the ability of both enzymes to hydrolyse the xylan structure. The use of an enzyme cocktail of rXynS1, AXE, and commercial cellulase (Celluclast® 1.5 L) for the hydrolysis of lignocellulosic biomass was more effective than that of commercial cellulase alone, thereby increasing the relative activity 2.3 fold. Conclusion The supplementation of rXynS1 with AXE enhanced the xylan degradation process via the de-esterification of acetyl groups in the xylan structure. Synergetic action of rXynS1 with commercial cellulase improved the hydrolysis of pre-treated lignocellulosic biomass; thus, rXynS1 could potentially be used in several industrial applications.

Industrially, lignin in pulp liquor not only obstructed the realization of value-added products, but also threatened the aquatic ecosystem. A magnetic composite Ca(OH)2/Fe3O4, combining the eco-friendliness of Ca-based flocculants with the convenience of magnetic flocculation, was simply compounded to efficiently flocculate lignin from papermaking black liquor. Morphologic and structural features of the flocculant before and after flocculation were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM) and X-ray photoelectron spectroscopy (XPS). The flocculant Ca(OH)2/Fe3O4 presented mesoporous and core-shell structure, which acted directly in the sodium lignin aqueous solution without pH neutralization, maintaining high lignin removal between 91% and 95%. Ca(OH)2/Fe3O4 showed a wider salts (0–1 mol/L NaCl) and pH (9–12.5) tolerance. In actual pulp black liquor, Ca(OH)2/Fe3O4 exhibited high removal of 90.16% and 85.93% for lignin and chemical oxygen demand (COD), respectively. The flocculation performance of Ca(OH)2/Fe3O4 outdistanced that of the traditional flocculant polyacrylamide (PAM). It displayed magnetically separable with a good reusability. The removal of lignin could attain 90.54% even after 6 cycles. Charge neutralization, micro-bridging, destabilization and sedimentation were involved in the process of lignin flocculation. Consequently, Ca(OH)2/Fe3O4 presented huge potential in papermaking black liquor treatment.

Benzene is a widely used commodity chemical, which is currently produced from fossil resources. Lignin, a waste from lignocellulosic biomass industry, is the most abundant renewable source of benzene ring in nature. Efficient production of benzene from lignin, which requires total transformation of Csp2-Csp3/Csp2-O into C-H bonds without side hydrogenation, is of great importance, but has not been realized. Here, we report that high-silica HY zeolite supported RuW alloy catalyst enables in situ refining of lignin, exclusively to benzene via coupling Bronsted acid catalyzed transformation of the Csp2-Csp3 bonds on the local structure of lignin molecule and RuW catalyzed hydrogenolysis of the Csp2-O bonds using the locally abstracted hydrogen from lignin molecule, affording a benzene yield of 18.8% on lignin weight basis in water system. The reaction mechanism is elucidated in detail by combination of control experiments and density functional theory calculations. The high-performance protocol can be readily scaled up to produce 8.5 g of benzene product from 50.0 g lignin without any saturation byproducts. This work opens the way to produce benzene using lignin as the feedstock efficiently., Efficient production of benzene from lignin is attractive and of great importance, but has not been realized. Here, the authors develop a strategy to transform lignin into benzene over a RuW/zeolite catalyst in water, and the yield of benzene can be as high as 18.8% on lignin weight basis.

Despite the great advantages of interconnected porous architectures of three-dimensional carbon as functional materials, apparent common drawbacks restricting their widespread applications are high cost and non-renewable of the carbon precursors and complicated activation procedures. In this study, biomass-derived honeycomb-like multilayered carbon (HMC) is synthesized by electrospraying and direct carbonization for the first time. Poly (methyl methacrylate) (PMMA) is mixed with biomass-derived lignin, the only carbon source, to form lignin/PMMA microspheres and microbowls by electrospraying. One-step carbonization of prepared micromaterials to obtain ultralight HMC, and the microstructures and pore size of carbon materials are controllable by adjusting the applied voltage of electrospraying. The obtained HMC-13 by carbonization of lignin/PMMA microspheres possesses interconnected carbon skeleton, partially graphitized structure and hierarchical pore system composed of macropores, mesopores and micropores. Benefiting from the structural advantages, HMC-13 as electrode of supercapacitor delivers a high specific capacitance of 348 F g−1 at 0.5 A g−1 in aqueous electrolytes. Additionally, the supercapacitor exhibits excellent cycling stability with only 4% capacitance loss after 10 000 cycles. Based on these encouraging results, environmental friendliness and facile synthesis strategy, the biomass-derived ultralight porous carbon material holds great promise for facilitating wasted biomass utilization and developing sustainable energy products.

The increased availability and production of lignocellulosic agroindustrial wastes has originated proposals for their use as raw material to obtain biofuels (ethanol and biodiesel) or derived products. However, for biomass generated from lignocellulosic residues to be successfully degraded, in most cases it requires a physical (thermal), chemical, or enzymatic pretreatment before the application of microbial or enzymatic fermentation technologies (biocatalysis). In the context of enzymatic technologies, fungi have demonstrated to produce enzymes capable of degrading polysaccharides like cellulose, hemicelluloses and pectin. Because of this ability for degrading lignocellulosic material, researchers are making efforts to isolate and identify fungal enzymes that could have a better activity for the degradation of plant cell walls and agroindustrial biomass. We performed an in silico analysis of alpha-glucoronidase in 82 accessions of the genus Aspergillus. The constructed dendrograms of amino acid sequences defined the formation of 6 groups (I, II, III, IV, V, and VI), which demonstrates the high diversity of the enzyme. Despite this ample divergence between enzyme groups, our 3D structure modeling showed both conservation and differences in amino acid residues participating in enzyme-substrate binding, which indicates the possibility that some enzymes are functionally specialized for the specific degradation of a substrate depending on the genetics of each species in the genus and the condition of the habitat where they evolved. The identification of alpha-glucuronidase isoenzymes would allow future use of genetic engineering and biocatalysis technologies aimed at specific production of the enzyme for its use in biotransformation.

In Earth matter evolution, the deoxygenation process plays a central role as plant and animal remains, which are composed by highly oxygenated molecules, were gradually deoxygenated into hydrocarbons to give fossil fuels deep in the Earth crust. The understanding of this process is becoming crucial to the entire world and to the sustainable development of mankind. This review provides a brief summary of the extensive deoxygenation research under mild, potentially sustainable conditions. We also summarize some challenges and opportunities for potential deoxygenation reactions in the future.

The present study aimed to obtain Kraft lignin microparticles by mechanical treatment and compare them with initial Kraft lignin in terms of their chemical, thermal and structural properties, as well as possible antioxidant and antimicrobial effects. Ball milling reduced the particle size from 6.6 µm to 3.1 µm. The zeta potential and polydispersity index measurements revealed greater instability of the microparticles, with a higher tendency to agglomerate, and higher homogeneity, when compared with Kraft lignin. These findings were also evidenced by scanning electron microscopy. The thermal degradation behavior was not affected by the mechanical treatment utilized in the production of microparticles. X-ray diffraction showed crystalline and amorphous regions in the particles. Infrared spectroscopy revealed that the microparticles maintained the characteristic peaks of Kraft lignin, with lower peak intensity. The samples proved high antioxidant potential, as determined by the 2,2-diphenyl-1-picryl-hydrazyl assay, regardless of the concentration studied. Therefore, the results of the study demonstrated that the obtained Kraft lignin microparticles could be suitable for the development of antioxidant food packaging.

Abstract Substituted benzenes such as phenol, benzaldehyde, and anisole are the simplest fragments from the lignin separation feedstocks. We have collected available primary experimental results on vapour pressures, enthalpies of phase transition, and enthalpies of combustion of phenol, benzaldehyde, and anisole. The resulting data on the gas-phase standard molar enthalpies of formation were validated using the quantum chemical method G4. The consistent sets of evaluated thermodynamic data are essential for calculating the energy balances of lignin conversion in the value-added chemicals and materials. Graphic abstract

This study assessed the capacity of leaf litters to adsorb copper ions applied as a copper-based pesticide. Leaf litters of two fruit tree species with different lignin/N ratios were examined to determine their protective role against the incorporation of Cu into soil. A leaf litter Cu-adsorption capacity assay and a degradation assay were performed using table grape (lignin/N = 2.35) and kiwi (lignin/N = 10.85) leaf litters. Table grape leaf litter had a significantly (p = 0.001) higher Cu-adsorption capacity (15,800 mg kg−1) than kiwi leaf litter (14,283 mg kg−1). Following leaf litter degradation, significant differences (p = 0.011) were observed in the release of Cu from Cu-enriched leaf litter into soil, showing that kiwi litter has a greater protective effect against the incorporation of Cu into soil, regardless of the amount of Cu applied. This protective role is reflected in a significantly higher (p = 0.015) Cu concentration in table grape soil (41.71 ± 2.14 mg kg−1) than in kiwi soil (35.87 ± 0.69 mg kg−1). Therefore, leaf litter with higher lignin/N ratio has greater protective role against copper incorporation into soil.