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Fungal necromass is increasingly recognized as a major component of soil organic matter, and identifying the factors that govern its formation is critical for understanding and predicting the global carbon cycle. Among these factors, the biochemical composition of mycelial residues at senescence, particularly melanin content, has been consistently identified as a key determinant of the fraction of fungal necromass that persists in soils. However, even non-melanized mycelial residues exhibit a recalcitrant fraction that resists microbial decomposition, and the reasons for this persistence are not well understood. To address this gap, we asked whether the growth stage at which a single non-melanized fungal species dies governs the decay of its necromass in soil. Using Neurospora crassa , we produced seven necromass types that ranged from early exponential growth to prolonged starvation and decomposed them in forest soil. Necromass derived from biomass experiencing net growth at the time of harvest decomposed up to ten times faster than necromass from starved cultures, which were undergoing biomass loss. By the end of decomposition, only about 10 % of necromass from early-growth-stage biomass remained, while nearly 65 % of necromass from starved biomass persisted. Differences in mycelial biochemical traits, particularly C:N ratio and the degree of branching of glucans, which varied with fungal growth stage at death, explained variation in both decay rates and the size of the persistent fractions. Our findings suggest that the growth stage of fungi at death is a key factor driving fungal necromass decay profiles, with potentially large consequences for the contribution of fungal necromass to soil organic matter stocks.

Diethylamine (DEA) is a known precursor to some of the most toxic chemical warfare agents (CWA) as both V-agents and Fourth Generation Agents (FGAs) contain the dialkylamine functionality. DEA is also a readily available commercial substance with extensive use in the chemical industry for legitimate purposes. Because of this potential dual use, it is desirable to develop methods to trace the origin of dialkylamines if they are used for illicit purposes. We herein demonstrate that it is possible to differentiate six commercial batches of DEA using position-specific isotope analysis (PSIA) by both ²H and ¹³C NMR. Using a high-field NMR spectrometer together with a cryogenic ²H probe, we have produced ²H-{¹H} NMR data with high accuracy and precision. The PSIA by NMR results show that the intramolecular ²H ratios of all six DEAs are significantly different while two of the six DEAs have unique ¹³C ratios. Further, the intramolecular isotopic variations can be used to link the DEAs to different suppliers. The two nuclei separately contribute to isotopic profiles of the DEAs. However, combining the two techniques provides a higher-resolved isotopic profile that can differentiate all DEAs and thus be useful in forensic investigations of illegal use of chemical weapons.

Processing of biomass residues for material and energy recovery generate effluents containing complex organic mixtures. Analyses of bulk parameters are conventional for characterization and classification of such effluents, where the limited information offered impedes the development of molecular level management practices. This study assessed the potential of solvent-selective complexity reduction of effluent dissolved organic matter (DOM) from anaerobic bioprocessing of biomass residues for 1H NMR spectroscopy. The DOM were acquired after filtration and drying of samples from seven full scale anaerobic bioreactor facilities with effluents used as biofertilizer. The 1H NMR spectra of DOM in indigenous solvent (water) revealed source dependent characteristics primarily due to variable abundance of aliphatic CCH in lipids and peptides, OCCH in carbohydrates, and olefinic and aromatic subunits. Dimethyl sulfoxide solubilized larger proportion of nonfunctionalized aliphatic and aromatic molecules, with 1H NMR features also varying depending on the DOM source. Methanol, however, reduced the 1H NMR spectral variability and dissolved sets of aliphatic and aromatic molecules from the dried DOM with similar 1H NMR features irrespective of their origin. Among the other solvents studied, the reactive dissolution by trifluoroacetic acid decomposed aliphatic units while enriching aromatics (i.e., CarH:CCH of 0.7 compared to 0.2 in water), also forming small (oligo)saccharides and peptide fragments. Acetone, dichloromethane, and acetonitrile extracted alkyl-rich molecules with varying degrees of functionalization. Acetonitrile separated a fraction enriched in aliphatic carboxylic acids, while dichloromethane mainly dissolved nonfunctionalized aliphatic hydrocarbons. It is proposed that a simple process of filtration, drying, and dissolution of effluent DOM in different solvents substantially reduces the complexity and heterogeneity of the organic mixtures enabling the structural discrimination of diverse molecular classes by 1H NMR spectroscopy.

In vivo proton magnetic resonance spectroscopy is a non-invasive technique used to measure biochemical molecules such as choline, glutamate, glutamine, and γ-Aminobutyric acid (GABA), many of which are relevant to anxiety and pain. However, the relationship between these neurotransmitters/metabolites and their implications for anxiety and subjective experience of pain is not yet fully understood. The objective of this cross-sectional study was to investigate the association between anxiety and pain ratings with levels of total choline, glutamate and GABA in brain regions known to be involved in anxiety and emotional experience of pain, specifically pregenual anterior cingulate cortex (pgACC) and dorsal anterior cingulate cortex (dACC). The levels of the neurotransmitters/metabolites were measured using GABA-edited Mescher–Garwood PRESS for GABA measurements, with the OFF-sequence measurements for total choline (tCho) and Glx (combined glutamate + glutamine). The total choline (tCho) signal in our analysis included glycerophosphocholine (GPC) and phosphocholine (PC), which is consistent with standard practices in MRS studies. This approach ensures a robust estimation of tCho concentrations across participants. The study collected data from 38 participants (17 males and 21 females). The analysis revealed a significant correlation between anxiety ratings before a standardized pain provocation and the rated pain unpleasantness during the pain provocation. tCho correlated negatively with these parameters in pgACC. A linear regression analysis indicated that tCho levels in pgACC have a significant negative association with anxiety and perceived pain when controlling for age, depressive symptoms, and alcohol and tobacco intake. We also found that sex significantly moderates the relationship between pgACC choline levels and pain unpleasantness. The study suggests that levels of choline, an essential precursor of acetylcholine, are associated with anxiety and perceived pain. These levels may influence how Glx and GABA contribute to affective pain experiences by modulating the balance between excitatory and inhibitory signals. However, future research is needed to identify the mechanisms involved. Furthermore, the study indicates that sex is a significant factor in this relationship, with lower choline levels being associated with higher pain ratings in females but not in males. This highlights the significance of addressing sex as a biological factor in pain research to better understand the different responses to treatments and to facilitate the development of more effective interventions in the future.

Dry and unproductive Scots pine forests in the northern boreal forest zone provide conditions where ground-dwelling lichens can thrive. These lichens are a crucial winter forage for reindeer. Reindeer reduce lichen biomass both by consumption and trampling, leading to cascading effects on microclimate, litter inputs, and soil carbon dynamics. To investigate long-term impacts of reindeer exclusion, we assessed the plant biomass, soil nutrients, and soil organic carbon (SOC) quantity and quality in three dry pine forest sites in northern Finland, where reindeer have been excluded for over 50 years. Within exclosures, lichen biomass was 4.5 times higher and dwarf shrub biomass nearly doubled compared to grazed controls. These vegetation changes were associated with a 33% higher soil moisture and 0.8 °C lower summer soil temperatures at 8 cm depth beneath the thicker lichen mats. The organic layer SOC stock was 28% higher in exclosures. Spectroscopic analysis using ¹³C NMR spectroscopy revealed 9.5% higher O-alkyl carbon (carbohydrates) content and lower methoxy (–5.1%), alkyl (–6.9%), and carbonyl (–8.7%) content, reflecting a younger, more labile carbon pool. Despite these changes, soil nutrient concentrations and C∶N ratios remained unchanged between treatments, suggesting that altered SOC storage and composition result primarily from increased litter inputs and microclimatic changes.  We conclude that in lichen-rich boreal forests, long-term reindeer exclusion enhances SOC stocks and promote a shift toward more decomposable soil organic matter, with potential implications for carbon stability following disturbance. 

Two major challenges in processing and applying lignin materials are their rigidity - being brittle at room temperature and lacking flowability when heated - and their heterogeneity, which causes wide and inconsistent variations in thermal properties. External plasticization is a resource-efficient way to improve the processability and mechanical properties of lignin and lignin-containing materials. However, how plasticizers distribute themselves within the lignin matrix and change its molecular superstructure is not known. In this work, the dispersal of plasticizer and its effect on lignin morphology and molecular mobility were studied using polarization transfer solid-state NMR (ssNMR) and small-angle X-ray scattering (SAXS). Two softwood lignins (Lignoboost and isolated from Norway spruce) were plasticized with three different plasticizers (glycerol, triacetin and diethyl phthalate). The molecular mobility of lignin-plasticizer blends under the glass transition temperature was found to differ substantially, with aprotic plasticizers enabling higher mobility in both types of lignins. The spin diffusion of lignin prior to plasticization was heterogeneous, indicating a heterogeneous chemical environment in the low nanometer range. Upon plasticization, the heterogeneity remained but changed in character. Plasticizer was now distributed unevenly between two lignin phases, but the two phases had achieved more similar dynamics. This convergence suggests the formation of a material with narrower range in physical properties - in line with the observed narrowing of the glass transition upon plasticization. Lignin blended with highly compatible plasticizers were found to have a more swollen morphology as revealed by SAXS. These findings indicate that an appropriate plasticizer will both reduce the temperature and the width of the glass transition, yield a more homogeneous material as well as form a glass that can accommodate stress.

Earthworms, as detritivores, play a significant role in breaking down soil organic carbon (SOC). The introduction of non-native earthworms to arctic ecosystems has, therefore, raised concerns about the potential impact they may have on one of the world's largest SOC reservoirs. Earthworms could also have considerable effects on plant productivity, and the lack of experimental studies quantifying their impact on carbon (C) reservoirs in both soil and plants makes it difficult to predict the effect of earthworms on ecosystem C storage. Here we experimentally tested how earthworms known to be non-native to arctic ecosystems (Aporrectodea spp. and Lumbricus spp.) affect C reservoirs in soil and plants (above and belowground separately) in two common tundra vegetation types (heath and meadow). Earthworms lowered the mean SOC pool and substantially altered SOC quality in meadow soils by increasing the proportion of aromatic-C compounds. Simultaneously, earthworms increased the C pool stored in plant biomass, which counteracted earthworm-induced SOC losses in meadow ecosystems. A positive earthworm effect on belowground biomass in heath soil facilitated a net ecosystem uptake of ∼0.84 kg C m−2 over the 4-year study period. The higher C uptake into plant biomass in the heath resulted in a notable increase of SOC but lower δ13C values, likely because of recently captured C being sourced from roots or litter. Our observations of vegetation-specific feedbacks between plants, earthworms, and soils advance our understanding of non-native earthworms' impact on SOC dynamics and C budgets in high-latitude ecosystems.

Aims: Plant inputs are the primary organic carbon source that transforms into soil organic matter (SOM) through microbial processing. One prevailing view is that lignin plays a major role in the accumulation of SOM. This study investigated lignin decomposition using wood from different genotypes of Populus tremula as the model substrate. The genotypes naturally varied in lignin content and composition, resulting in high and low lignin substrates.

Methods: The wood was inoculated with fresh soil and decomposition was interpreted through mass loss and CO2 produced during a 12-month lab incubation. Detailed information on the decomposition patterns of lignin was obtained by Two-dimensional Nuclear magnetic resonance (2D NMR) spectroscopy on four occasions during the incubations.

Results: The lignin content per se did not affect the overall decomposition and ~ 60% of the mass was lost in both substrates. In addition, no differences in oxidative enzyme activity could be observed, and the rate of lignin decomposition was similar to that of the carbohydrates. The 2D NMR analysis showed the oxidized syringyl present in the initial samples was the most resistant to degradation among lignin subunits as it followed the order p-hydroxybenzoates > syringyl > guaiacyl > oxidized syringyl. Furthermore, the degradability of β–O–4 linkages in the lignin varied depending on the subunit (syringyl or guaiacyl) it is attached to.

Conclusions: Our study demonstrates that lignin contains fractions that are easily degradable and can break down alongside carbohydrates. Thus, the initial differences in lignin content per se do not necessarily affect magnitude of SOM accumulation.

To produce chitosan is an interesting research. Chitosan is an important polysaccharide in terms of its various applications in industries and is produced from chitin, an abundant biopolymer in crustacean shell biomass wastes. Traditional processes for chitosan manufacture are commonly based on highly concentrated alkaline or acid solutions which are, however, severely eroding and harmful to the environment. In this study, we have described a ‘greener’ method using 1-ethyl-3-methylimidazolium acetate, [Emim][OAc] ionic liquid (IL), for decrystallization of shrimp crystalline chitin flakes followed by a microwave-mediated NaOH or tetrabutylammonium hydroxide, [TBA][OH], solution-based deacetylation for chitosan production. The decrease in crystallinity in IL pre-treated chitin was confirmed by XRD and SEM analysis which subsequently benefited chitosan production with up to 85% degree of deacetylation (%DDA) in shorter time periods (1-2 hours) and lower alkaline concentrations (20-40%). The %DDA in chitin/chitosan was estimated via FT-IR and NMR analysis. Notably, we could regenerate the ionic liquids: in case of [Emim][OAc] 97 wt.% and in case of [TBA][OH] 83 wt.% could be reused. Roles of ionic liquids in the process were discussed. Molecular dynamics (MD) simulations showed the roles of [TBA]+ cations in the molecular driving forces of [TBA][OH]-induced deacetylation mechanism. The strategy promises a sustainable and milder reaction approach to the existing highly corrosive alkaline- or acid-involved processes for chitosan production.

The major ampullate Spidroin 1 (MaSp1) is the main protein of the dragline spider silk. The C-terminal (CT) domain of MaSp1 is crucial for the self-assembly into fibers but the details of how it contributes to the fiber formation remain unsolved. Here we exploit the fact that the CT domain can form silk-like fibers by itself to gain knowledge about this transition. Structural investigations of fibers from recombinantly produced CT domain from E. australis MaSp1 reveal an α-helix to β-sheet transition upon fiber formation and highlight the helix No4 segment as most likely to initiate the structural conversion. This prediction is corroborated by the finding that a peptide corresponding to helix No4 has the ability of pH-induced conversion into β-sheets and self-assembly into nanofibrils. Our results provide structural information about the CT domain in fiber form and clues about its role in triggering the structural conversion of spidroins during fiber assembly.