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At least 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Lignin - A green material for antibacterial application — A review

Lignin's antibacterial properties have become increasingly relevant due to the rise of microbial infectious diseases and antibiotic resistance. Lignin is capable of interacting electrostatically with bacteria and contains polyphenols that cause damage to their cell walls. These features make lignin a desirable material to exhibit antibacterial behavior. Therefore, lignin in antibacterial applications offers a novel approach to address the growing need for sustainable and effective antibacterial materials. Recent research has explored the incorporation of lignin in various biomedical applications, such as wound dressings, implants, and drug delivery systems, highlighting their potential as a sustainable alternative to synthetic antibacterial agents. Furthermore, the development of lignin-based nanomaterials with enhanced antimicrobial activity is an active area of research that holds great promise for the future. Here, in this review, we have provided a summary of how lignin can be incorporated into different forms, such as composite and non-composite synthesis of antibacterial agents and their performances. The challenges and future considerations are also discussed in this review article.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Determination of a suitable molar absorption coefficient (ε) for lignin analysis of fibrous plants using the CASA method

In this study, the benchmarking and applicability of the CASA method for the analysis of fibrous plants, such as flax, hemp, and jute, is evaluated. Lignin is a phenolic biopolymer present in plant cell walls and is composed of three primary monomeric units, designated G, S, and H. Various factors, such as the genetic variability, influence the relative proportions of these units in plant samples. Recently, the cysteine-assisted sulfuric acid (CASA) method has been introduced as a rapid method for the quantification of lignin in wood samples. The aim of this study is to establish a suitable molar absorption coefficient (ε, L·g –1 ·cm –1 ) to adapt the CASA method for use with annual plant fibers. This investigation was motivated by the technical advantages of the CASA method, including higher throughput, lower reaction temperatures, and ecological benefits due to the absence of carcinogenic, mutagenic, or reprotoxic (CMR) substances and the need for minimal sample quantities. In this method, lignin solubilization is facilitated by cysteine, which is an amino acid that enhances the reaction kinetics, using a one-hour incubation period. However, as with any spectrophotometric technique, the CASA method depends on a molar absorption coefficient (ε) that varies according to the ratio of the aromatic units within the polymer. To evaluate the suitability of CASA for quantifying lignin in economically significant plant fibers, we investigate the impact of the unit ratios on the accuracy of ε. The results are compared with those of two widely recognized lignin analytical methods: the Klason method, which is a gravimetric reference method, and the acetyl bromide soluble lignin method, which is the most commonly used spectrophotometric approach. The final ε obtained in this study reveals a relative difference in lignin content ranging from –8 % to +9 % based on a comparison between the CASA and Klason methods across different industrial hemp varieties. As a result, using known G:S ratios in annual fibrous plants, ε can be estimated from our results.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Systems biology-guided understanding of white-rot fungi for biotechnological applications: A review

Plant-derived biomass is the most abundant biogenic carbon source on Earth. Despite this, only a small clade of organisms known as white-rot fungi (WRF) can efficiently break down both the polysaccharide and lignin components of plant cell walls. This unique ability imparts a key role for WRF in global carbon cycling and highlights their potential utilization in diverse biotechnological applications. To date, research on WRF has primarily focused on their extracellular 'digestive enzymes', while knowledge of their intracellular metabolism remains underexplored. Systems biology has been demonstrated to be a powerful approach to elucidate biological processes in numerous organisms, including WRF. Thus, here we review systems biology methods applied to WRF to date, highlight observations related to their intracellular metabolism, and conduct a comparative extracellular proteomic analysis to establish further correlations between WRF species, enzymes, and cultivation conditions. Lastly, we discuss biotechnological opportunities of WRF as well as challenges and future research directions.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Lytic polysaccharide monooxygenase synergized with lignin-degrading enzymes for efficient lignin degradation

Even though the discovery of lytic polysaccharide monooxygenases (LPMOs) has fundamentally shifted our understanding of biomass degradation, most of the current studies focused on their roles in carbohydrate oxidation. However, no study demonstrated if LPMO could directly participate to the process of lignin degradation in lignin-degrading microbes. This study showed that LPMO could synergize with lignin-degrading enzymes for efficient lignin degradation in white-rot fungi. The transcriptomics analysis of fungi Irpex lacteus and Dichomitus squalens during their lignocellulosic biomass degradation processes surprisingly highlighted that LPMOs co-regulated with lignin-degrading enzymes, indicating their more versatile roles in the redox network. Biochemical analysis further confirmed that the purified LPMO from I. lacteus CD2 could use diverse electron donors to produce H 2 O 2 , drive Fenton reaction, and synergize with manganese peroxidase for lignin oxidation. The results thus indicated that LPMO might uniquely leverage the redox network toward dynamic and efficient degradation of different cell wall components.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Molecular simulation of lignin-related aromatic compound permeation through gram-negative bacterial outer membranes

Lignin, an abundant aromatic heteropolymer in secondary plant cell walls, is the single largest source of renewable aromatics in the biosphere. Leveraging this resource for renewable bioproducts through targeted microbial action depends on lignin fragment uptake by microbial hosts and subsequent enzymatic action to obtain the desired product. Recent computational work has emphasized that bacterial inner membranes are permeable to many aromatic compounds expected from lignin depolymerization processes. In this study, we expand on these findings through simulations for 42 lignin-related compounds across a gram-negative bacterial outer membrane model. Unbiased simulation trajectories indicate that spontaneous crossing for the full outer membrane is relatively rare at molecular simulation timescales, primarily due to preferential membrane partitioning and slow diffusion within the lipopolysaccharide layer within the outer membrane. Membrane partitioning and permeability coefficients were determined through replica exchange umbrella sampling simulations to overcome sampling limitations. We find that the glycosylated lipopolysaccharides found in the outer membrane increase the permeation barrier to many lignin-related compounds, particularly the most hydrophobic compounds. However, the effect is relatively modest; at industrially relevant concentrations, uncharged lignin-related compounds will readily diffuse across the outer membrane without the need for specific porins. Together, our results provide insight into the permeability of the bacterial outer membrane for assessing lignin fragment uptake and the future production of renewable bioproducts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

A broad specificity β-propeller enzyme from Rhodopseudomonas palustris that hydrolyzes many lactones including γ-valerolactone

Lactones are prevalent in biological and industrial settings, yet there is a lack of information regarding enzymes used to metabolize these compounds. One compound, γ-valerolactone (GVL), is used as a solvent to dissolve plant cell walls into sugars and aromatic molecules for subsequent microbial conversion to fuels and chemicals. Despite the promise of GVL as a renewable solvent for biomass deconstruction, residual GVL can be toxic to microbial fermentation. Here, we identified a Ca 2+ -dependent enzyme from Rhodopseudomonas palustris (Rpa3624) and showed that it can hydrolyze aliphatic and aromatic lactones and esters, including GVL. Maximum-likelihood phylogenetic analysis of other related lactonases with experimentally determined substrate preferences shows that Rpa3624 separates by sequence motifs into a subclade with preference for hydrophobic substrates. Additionally, we solved crystal structures of this β-propeller enzyme separately with either phosphate, an inhibitor, or a mixture of GVL and products to define an active site where calcium-bound water and calcium-bound aspartic and glutamic acid residues make close contact with substrate and product. Our kinetic characterization of WT and mutant enzymes combined with structural insights inform a reaction mechanism that centers around activation of a calcium-bound water molecule promoted by general base catalysis and close contacts with substrate and a potential intermediate. Similarity of Rpa3624 with other β-propeller lactonases suggests this mechanism may be relevant for other members of this emerging class of versatile catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

One-pot generation of lignin microspheres and digestible substrate with a polyol-DES pretreatment in high solid loading

Previous lignin microspheres (LMS) preparation needs multiple steps with very low yield and high cost. Herein, we developed a high-solid deep eutectic solvent (DES) pretreatment for an effective lignin fractionation and enzymatic saccharification of moso bamboo under mild temperature (110 °C) with high-solid loading. Lignin was significantly removed from the plant cell wall, and cellulose properties (e.g., crystallinity and degree of polymerization) were also altered during the pretreatment. As a result, the enzymatic digestibility of the pretreated bamboo was dramatically increased. Uniform micro-spherical lignin was directly produced from the pretreatment system, and its particle size could be regulated by controlling the solid loadings and pretreatment temperatures. The lignin microspheres formation mechanism was investigated by analyzing the lignin's size distribution, molecular weight distribution, chemical structure, and hydrophobicity. The DES showed excellent recyclability, and the recycled DES could still remove 42.78% lignin even after 7th circulation associated with 100% glucan saccharification. Further, the mass balance based on 1000 g biomass showed that 196.28 g LMS was directly recovered, which exhibited a high RhB adsorption. Besides, 404.91 g glucose and 36.67 g xylose were obtained after the enzymatic saccharification process. Specifically, GAPI analysis exhibited a near total green and yellow portions of the pictogram, indicating our DES process was green enough to make this biorefinery sustainable. Overall, the proposed DES generated synergistic productions of digestible solid and LMS which could contribute to establish a green and sustainable biorefinery sequence with diverse outputs in one pot.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Exceptional thermal stability of additively manufactured CoCrFeMnNi high-entropy alloy with cellular dislocation structures

CoCrFeMnNi high-entropy alloy (HEA) was additively manufactured (AM) by laser powder-bed fusion (L-PBF). The AM CoCrFeMnNi has prominent cellular dislocation structures with a small number of Mn-rich oxides. The thermal stability of the AM CoCrFeMnNi was investigated by isochronal annealing treatment at various temperatures from 400 to 1300°C for 1h. Microstructural analysis shows slow dislocation recovery, retarded recrystallization process, and precipitation of additional Cr-Mn based oxides during thermal annealing, resulting in exceptional thermal stability and retained high hardness at elevated temperatures. Further, by thermodynamic calculations, a low stored energy of 1.31 MJ/m 3 and a high activation energy of 353 kJ/mol for recrystallization were estimated for the AM CoCrFeMnNi. The exceptional thermal stability of the AM CoCrFeMnNi HEA is mechanistically attributed to the low crystallographic misorientations across the dislocation cell walls, sluggish atomic diffusion, and the pinning effects of the oxide nanoprecipitates.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Hydrogen influences thermal activation parameters for dislocation glide during low cycle fatigue of 316L stainless steel

Measurements of activation areas are used to investigate the effect of hydrogen on the kinetics of dislocation glide during cyclic deformation in cold-worked 316L stainless steel. Non-charged and hydrogen-precharged (H-precharged) specimens were tested in low cycle fatigue (LCF) under plastic strain control. A series of plastic strain rate changes was performed periodically at the peak true plastic strain from the first cycle to half-life, and at various plastic strain values around stable hysteresis loops near half-life to determine the operational activation area, Δ a ∗. Both material conditions demonstrate a rapid increase in Δ a ∗ during the initial rapid softening followed by a region of approximately constant values coinciding with a reduced rate of softening. Near half-life, hydrogen reduces Δ a ∗ at a given true stress due to its effect on the activation distance and obstacle spacing. The magnitudes of Δ a ∗ reveal that bypassing solutes, cutting forest dislocations, and initiating cross slip are important mechanisms of thermally activated dislocation glide at all amplitudes, except hydrogen suppresses cross slip at the lowest plastic strain amplitudes. These results are supported by electron microscopy characterization of deformed microstructures. A Haasen plot analysis indicates that forest dislocations control the kinetics of deformation in both material conditions. It also reveals the presence of athermal obstacles in both non-charged and H-precharged conditions, likely dense dislocation tangles and cell walls. Additionally, the effect of hydrogen on microstructure evolution (by reducing the propensity for cross slip) leads to a dependence of athermal stress on plastic strain amplitude.

Activation area↗
DOE OSTI2025

Comparative transcriptomics of CAZy enzymes in white- and brown-rot agaricomycetes: Evolutionary insights into lignocellulose degradation and the relevance of GH16 glycoside hydrolase functional divergence

White-rot and brown-rot fungi (WRF and BRF, respectively) decompose lignocellulose, the main structural component of plant biomass, through distinct mechanisms. This study examines the transcriptomic responses of three WRF species (Pleurotus ostreatus, Phanerochaete chrysosporium, and Heterobasidion irregulare) and two BRF species (Fomitopsis schrenkii and Rhodonia placenta) grown on poplar wood (W) and glucose (G) as sole carbon sources. RNA-seq analysis revealed upregulation of carbohydrate-active enzymes (CAZymes) linked to lignocellulose degradation. WRF displayed a broader enzymatic repertoire, whereas BRF employed a more selective approach. Among these responses, GH16 glycoside hydrolases were consistently upregulated across all species, including BRF. Since GH16 enzymes are involved in both plant hemicellulose modification and cell wall remodeling, their wood-induced expression may reflect multiple processes rather than a single conserved wood-decay mechanism. Structural and phylogenetic analyses revealed species-specific divergence, consistent with potential functional specialization. These findings broaden our understanding of fungal enzymatic strategies and highlight GH16 enzymes as candidates for further study. Beyond the immediate context of wood decay, this work has broader implications for fungal ecology, evolutionary biology, and biotechnological applications such as biomass conversion and sustainable bioenergy.

Fungal ecological strategies↗
DOE OSTI2021

Effects of different pelleting technologies and parameters on pretreatment and enzymatic saccharification of lignocellulosic biomass

Densification of lignocellulosic biomass is beneficial for its logistics, and in some situations, also for its application in biorefineries. In this study, industrial pellets and laboratory-made pellets produced at different die temperatures (90, 125 °C) from wheat straw, beech, and pine were pretreated (by dilute acid and alkali) and enzymatically hydrolyzed to study the effects of pelleting on pretreatment and sugar yield. The results showed that industrial pelleting positively affected sugar yield of the three biomasses for both acid and alkaline pretreatments, while laboratory pelleting affected sugar yield differently related to pretreatment types and biomass species. Pelleting disturbed biomass cell wall structure and affected the stability of hemicellulose and β-O-4' linkages in lignin. The extent of hemicellulose solubility during acid pretreatment and the amount of lignin β-O-4' ether linkages present in acid pretreated substrates could serve as indicators of the effect of pelleting on sugar yield. The structural modifications caused by pelleting and their effects on the enzymatic sugar yield correlate tightly to pelleting technology, pretreatment method, and biomass species. As a result, the discrepant effects between industrial and laboratory pelleting on sugar yield observed in this study should be considered when designing future studies.

09 BIOMASS FUELS↗
DOE OSTI2024

Biomolecular budget of persistent, microbial-derived soil organic carbon: The importance of underexplored pools

The details of how soil microorganisms contribute to stable soil organic carbon pools are a pressing knowledge gap with direct implications for soil health and climate mitigation. It is now recognized that microbial necromass contributes substantially to the formation of stable soil carbon. However, the quantification of necromass in soils has largely been limited to model molecules such as aminosugar biomarkers. The abundance and chemical composition of other persistent microbial residues remain unresolved, particularly concerning how these pools may vary with microbial community structure, soil texture, and management practices. We use yearlong soil incubation experiments with an isotopic tracer to quantify the composition of persistent residues derived from microbial communities inhabiting sand or silt dominated soil with annual (corn) or perennial (switchgrass) monocultures. Persistent microbial residues were recovered in diverse soil biomolecular pools including metabolites, proteins, lipids, and mineral-associated organic matter (MAOM). The relative abundances of microbial contributions to necromass pools were consistent across cropping systems and soil textures. The greatest residue accumulation was not recovered in MAOM but in the light density fraction of soil debris that persisted after extraction by chemical fractionation using organic solvents. Necromass abundance was positively correlated with microbial biomass abundance and revealed a possible role of cell wall morphology in enhancing microbial carbon persistence; while gram-negative bacteria accounted for the greatest contribution to microbial-derived carbon by mass at one year, residues from gram-positive Actinobacteria and Firmicutes showed greater durability. Together these results offer a quantitative assessment of the relative importance of diverse molecular classes for generating durable soil carbon.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Higher levels of mixed-linkage (1,3;1,4)-β-glucan in transgenic grasses may impact soil C processing

Carbohydrates, including mixed-linkage glucan (MLG), in grass cell walls make them a valuable potential feedstock for biofuel production. Hence, the development of transgenic grasses with elevated levels of MLG is being actively pursued worldwide. Changes in chemical and physical root characteristics of MLG-overproducing transgenic plants can affect processing of the root-derived carbon (C) by soil microorganisms, impacting soil C cycling. Here, this study is the first attempt to elucidate the impact of MLG-related genetic modifications on root traits, root decomposition, and soil C processing. We explored four genotypes of Brachypodium ( Brachypodium distachyon ): a wildtype, a loss-of-function mutant with low MLG, an MLG overexpressing line, and a line lacking MLG hydrolase (with high MLG), incubating their roots in soils of two contrasting vegetation histories: monoculture switchgrass and polyculture restored prairie. The four genotypes exhibited contrasting root MLG and soluble sugar concentrations, and different growth phenotypes. Roots with the highest MLG content resulted in a ∼55 % increase in microbial biomass C compared to wildtype in both soils. However, the genotype effects on C mineralization rates were influenced by the vegetation history, with significant effects observed only in the soil from switchgrass but not prairie origin. While further work is required to understand the full impact of MLG-overproducing plants on soil C accrual, our findings suggest that their influence on soil C processes cannot be discounted.

Brachypodium distachyon↗
DOE OSTI2023

Insights into substrate coordination and glycosyl transfer of poplar cellulose synthase-8

Cellulose is an abundant cell wall component of land plants. It is synthesized from UDP-activated glucose molecules by cellulose synthase, a membrane-integrated processive glycosyltransferase. Cellulose synthase couples the elongation of the cellulose polymer with its translocation across the plasma membrane. Here, we present substrate- and product-bound cryogenic electron microscopy structures of the homotrimeric cellulose synthase isoform-8 (CesA8) from hybrid aspen (poplar). UDP-glucose binds to a conserved catalytic pocket adjacent to the entrance to a transmembrane channel. The substrate’s glucosyl unit is coordinated by conserved residues of the glycosyltransferase domain and amphipathic interface helices. Site-directed mutagenesis of a conserved gating loop capping the active site reveals its critical function for catalytic activity. Molecular dynamics simulations reveal prolonged interactions of the gating loop with the substrate molecule, particularly across its central conserved region. These transient interactions likely facilitate the proper positioning of the substrate molecule for glycosyl transfer and cellulose translocation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Metabolic modulation: Pneumocystis phosphoglucomutase is a target influencing host recognition

Herein, this manuscript explores the significance of the phosphoglucomutase (PGM) enzyme in Pneumocystis spp., focusing on its role in fungal surface mannoprotein formation. Through expression of the Pneumocystis murina Pmpgm2 in a Saccharomyces cerevisiae pgm2Δ strain, we demonstrate restoration of binding to the mannose receptor (MR) and macrophages to wildtype yeast levels in this complemented strain. Gas Chromatography-Mass Spectroscopy (GC-MS) confirmed reduced mannose content in the pgm2Δ yeast strain compared to the wild-type and complemented Pmpgm2 cDNA-expressing strains. This study underscores fungal PGM function in dolichol glucosyl phosphate biosynthesis, crucial for proper cell wall mannoprotein formation. Furthermore, highlighting the conservation of targetable cysteine residues across fungal pathogens, PGM inhibition maybe a potential therapeutic strategy against a broad spectrum of fungal infections.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Metabolism of Syringyl Lignin-Derived Compounds in Pseudomonas putida Enables Convergent Production of 2-Pyrone-4,6-Dicarboxylic Acid

Valorization of lignin, an abundant component of plant cell walls, is critical to enabling the lignocellulosic bioeconomy. Biological funneling using microbial biocatalysts has emerged as an attractive approach to convert complex mixtures of lignin depolymerization products to value-added compounds. Ideally, biocatalysts would convert aromatic compounds derived from the three canonical types of lignin: syringyl (S), guaiacyl (G), and p-hydroxyphenyl (H). Pseudomonas putida KT2440 (hereafter KT2440) has been developed as a biocatalyst owing in part to its native catabolic capabilities but is not known to catabolize S-type lignin-derived compounds. Here, we demonstrate that syringate, a common S-type lignin-derived compound, is utilized by KT2440 only in the presence of another energy source or when vanAB was overexpressed, as syringate was found to be O-demethylated to gallate by VanAB, a two-component monooxygenase, and further catabolized via extradiol cleavage. Unexpectedly, the specificity (kcat/KM) of VanAB for syringate was within 25% that for vanillate and O-demethylation of both substrates was well-coupled to O2 consumption. However, the native KT2440 gallate-cleaving dioxygenase, GalA, was potently inactivated by 3-O-methylgallate. To engineer a biocatalyst to simultaneously convert S-, G-, and H-type monomers, we therefore employed VanAB from Pseudomonas sp. HR199, which has lower activity for 3MGA, and LigAB, an extradiol dioxygenase able to cleave protocatechuate and 3-O-methylgallate. This strain converted 93% of a mixture of lignin monomers to 2-pyrone-4,6-dicarboxylate, a promising bio-based chemical. Overall, this study elucidates a native pathway in KT2440 for catabolizing S-type lignin-derived compounds and demonstrates the potential of this robust chassis for lignin valorization.

2-pyrone-4,6-dicarboxylic acid↗
DOE OSTI2026

Engineered plants for the production of the antioxidants arbutin and gallate

The shikimate pathway is a crucial metabolic route for the biosynthesis of numerous valuable chemicals. In this study, we engineered the shikimate pathway in plants via expression of microbial enzymes to produce the two important antioxidants gallate and arbutin. The engineered pathways utilize the aromatics protocatechuate and 4-hydroxybenzoate as metabolic intermediates. Through transient expression in Nicotiana benthamiana leaves, we first identified biosynthetic routes for the production of gallate from either chorismate or 3-dehydroshikimate. Gallate production was then achieved in Arabidopsis using a genetic background that overproduces protocatechuate and via expression of a mutated version of the 4-hydroxybenzoate hydroxylase PobA from Pseudomonas sp. Arbutin production was obtained in Arabidopsis using a genetic background that overproduces 4-hydroxybenzoate and via expression of the monooxygenase MNX1 from Candida parapsilosis. The best Arabidopsis transgenic lines accumulated gallate and arbutin in the range of 0.25 and 0.93 dry weight % (dwt%), respectively. Using sorghum for large-scale in planta production, the titers of gallate and arbutin produced from the intermediate 4-hydroxybenzoate reached 0.58 dwt% and 0.50 dwt%, respectively, in mature transgenic plants, surpassing levels typically observed in plants that naturally produce these compounds. Gallate and arbutin were readily extracted from plant tissues using methanol solvent. Analysis of extractive-free biomass showed only trace amounts of gallate and its precursors 4-hydroxybenzoate and protocatechuate crosslinked to cell walls, suggesting that they mainly occur as soluble conjugated forms stored in the vacuole. This study presents alternative synthesis routes using plant hosts for the eco-friendly production of gallate and arbutin.

Antioxidant↗
DOE OSTI2023

Atomistic Simulations of Polydisperse Lignin Melts Using Simple Polydisperse Residue Input Generator

Understanding the physics of lignin will help rationalize its function in plant cell walls as well as aiding practical applications such as deriving biofuels and bioproducts. Here, in this work, we present SPRIG (Simple Polydisperse Residue Input Generator), a program for generating atomic-detail models of random polydisperse lignin copolymer melts i.e., the state most commonly found in nature. Using these models, we use all-atom molecular dynamics (MD) simulations to investigate the conformational and dynamic properties of polydisperse melts representative of switchgrass (Panicum virgatum L.) lignin. Polydispersity, branching and monolignol sequence are found to not affect the calculated glass transition temperature, T g . The Flory–Huggins scaling parameter for the segmental radius of gyration is 0.42 ± 0.02, indicating that the chains exhibit statistics that lie between a globular chain and an ideal Gaussian chain. Below T g the atomic mean squared displacements are independent of molecular weight. In contrast, above T g , they decrease with increasing molecular weight. Therefore, a monodisperse lignin melt is a good approximation to this polydisperse lignin when only static properties are probed, whereas the molecular weight distribution needs to be considered while analyzing lignin dynamics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗