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Background: Electroconvulsive therapy (ECT) is the most effective treatment for severe and treatment-resistant depression, but its biological mechanisms remain poorly understood. Given the pivotal role of mitochondria in cellular energy metabolism and their proposed involvement in the pathology of depression, we aimed to investigate whether ECT alters mitochondrial metabolism.

Methods: We included 102 patients with major depressive disorder referred for ECT at 7 Swedish hospitals. Fasting serum samples were collected at 3 time points: immediately before the first ECT session (T0), 30 minutes after the first session (T1), and before the sixth session (T2). Proton nuclear magnetic resonance spectroscopy was used to quantify metabolites related to the tricarboxylic acid cycle and amino acid metabolism.

Results: Acutely (T0→T1), serum levels of citrate, glucose, glutamine, and pyruvate increased significantly, while formate and phenylalanine decreased. Across the treatment course (T0→T2), alanine and pyruvate levels increased, whereas the ketone bodies acetoacetate, acetone, and 3-hydroxybutyrate decreased significantly. An exploratory analysis indicated that the reduction in ketone bodies (T0→T2) was confined to patients showing clinical improvement, as defined by the Clinical Global Impressions-Improvement scale.

Conclusions: ECT induces both acute and sustained alterations in mitochondrial energy metabolism. These findings suggest that ECT modulates systemic mitochondrial function, warranting further investigation into how these metabolic changes relate to clinical improvement.

Lignin, a complex polymer of phenylpropane units, is a crucial component of the cell walls of vascular plants, providing structural integrity, functionality for the transport of water and nutrients, and enhanced resistance to microbial attack. This chapter delves into the intricate structure of lignin, highlighting its diverse chemical composition and exploring the underlying biosynthetic pathways. In addition to structural insights, this chapter explores advanced analytical techniques used to characterize lignin, including, for example, methods based on spectroscopy, chromatography, and mass spectrometry. This chapter also highlights the various industrial, environmental, and biotechnological applications of lignin analysis. Finally, we address current challenges in lignin analysis and propose future directions to advance the field. This comprehensive examination of lignin structure and analytics aims to enhance our understanding and utilization of this vital biopolymer.

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.

Developing effective fractionation methods remains challenging in biorefining. γ-Valerolactone (GVL) is a promising green solvent, yet its application in softwood biorefineries is still underexplored. In this study, GVL pretreatment for softwood biorefining was assessed at laboratory and pilot scales. The effects of temperature (170–210 °C), time (20–60 min), and GVL-to-water ratios (20:80 – 80:20 %) on the biorefining of spruce sawdust were initially investigated through lab-scale experiments using a 1-L reactor. A GVL/water solution at a 40:60 ratio, assisted by 0.4 g of sulfuric acid per 100 g of biomass, enabled the solubilization of up to 81.4 % of lignin and nearly the entire hemicellulosic fraction, while effectively preserving cellulose, which was subsequently saccharified with over 90 % conversion. Lignin was regenerated from the liquors and characterized using pyrolysis-gas chromatography/mass spectrometry, high-performance size-exclusion chromatography, Fourier-transform infrared spectroscopy, and 1H-13C heteronuclear single-quantum coherence nuclear magnetic resonance spectroscopy. The biorefinery concept was successfully scaled up and validated at pilot scale in a 50-L reactor, where enzymatic saccharification of the resulting cellulosic pulp produced hydrolysates that, upon fermentation, yielded 231.4 g of ethanol per kilogram of pulp. Lignin regenerated from the pilot-scale pretreatment liquors (118.9 g per kilogram of raw sawdust) and the lignin-rich saccharification residue (182.7 g/kg) were subjected to hydrothermal liquefaction, and the resulting biocrudes were characterized to assess their potential for biofuel formulation. The study showed the suitability of GVL for spruce biorefining to achieve high recovery of digestible cellulose, lignin and hemicelluloses fractions, that are subsequently valuable for chemicals and fuels production.

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.

Wood is the most abundant renewable natural resource composed of different polysaccharides and lignin, but its utilisation is hampered by intermolecular linkages between these components forming lignin-carbohydrate complexes (LCCs) causing recalcitrance. The links between glucuronoxylan and the γ-C of lignin (γ-ester linkages) are thought to contribute to one-third of LCCs, but direct evidence for their natural occurrence and their role in recalcitrance has been scarce so far. To address these issues, Phanerochaete carnosa glucuronoyl esterase (PcGCE), hydrolysing γ-ester linkages, was expressed in cell walls of developing wood in hybrid aspen (Populus tremula L. × tremuloides Michx.). The enzyme reduced HSQC 2D NMR signals corresponding to the γ-esters and xylan in dioxane-extracted LCCs without altering glucuronoxylan content or structure. This increased acid solubility of lignin and lignin content. Reduced wood recalcitrance was shown by increased sugar yields and glucose production rates (by approx. 20%) in saccharification without pretreatment and increased xylan extractability by subcritical water (by approx. 70%). Moreover, trees expressing PcGCE exhibited greater primary and secondary growth. Transcriptomics and metabolomics analyses in developing wood suggested that growth could have been induced by a higher transcription of SMR2 and RPOTmp, which was likely triggered by the secondary cell wall integrity signalling. The results provide evidence for the natural existence of LCC γ-esters and their significant contribution to lignocellulose recalcitrance. Furthermore, they show that reducing γ-ester linkages could increase plant productivity.

Microbial exopolysaccharides (EPSs) have attracted increasing attention due to their versatile applications across diverse areas. However, large-scale production of EPSs remains challenging due to the high production costs, primarily driven by the use of synthetic carbon sources. This study demonstrates the potential of quinoa stalk hydrolysates as a sustainable alternative for EPS production using a halotolerant bacterial strain that was isolated from a hypersaline environment and termed SU4M. The bacterial isolate was identified through 16S rRNA and gyrB sequencing as a Bacillus swezeyi strain, and was then cultivated in quinoa stalk hydrolysates. The hydrolysates were produced by acid-catalyzed hydrothermal pretreatment using either sulfuric acid or phosphoric acid, followed by enzymatic saccharification. Fermentation experiments conducted in both shake flasks and bioreactors demonstrated that B. swezeyi SU4M utilized glucose from the hydrolysates efficiently, resulting in significantly higher biomass (5.1 ± 0.1 g L−1) and EPS production (1.2 ± <0.1 g L−1) compared to synthetic media (4.3 ± 0.1 g L−1 and 1.1 ± <0.1 g L−1). The kinetic analysis revealed distinct substrate consumption rates and growth patterns, with hydrolysates enhancing EPS yields under single-pulse fed-batch conditions. Advanced characterization techniques, including compositional analysis, Fourier transform infrared (FTIR) spectroscopy, 1H and 1H-13C heteronuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR), high-performance size-exclusion chromatography (HPSEC), and thermogravimetric analysis (TGA), confirmed that the EPSs derived from hydrolysates were heteropolysaccharides with close structural similarities to those obtained from synthetic media. These findings underscore the potential of quinoa stalk hydrolysates as a biobased alternative to synthetic media as a substrate for EPS production.

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.

The main protease M^pro, nsp5, of SARS-CoV-2 (SCoV2) is one of its most attractive drug targets. Here, we report primary screening data using nuclear magnetic resonance spectroscopy (NMR) of four different libraries and detailed follow-up synthesis on the promising uracil-containing fragment Z604 derived from these libraries. Z604 shows time-dependent binding. Its inhibitory effect is sensitive to reducing conditions. Starting with Z604, we synthesized and characterized 13 compounds designed by fragment growth strategies. Each compound was characterized by NMR and/or activity assays to investigate their interaction with M^pro. These investigations resulted in the four-armed compound 35b that binds directly to M^pro. 35b could be cocrystallized with M^pro revealing its noncovalent binding mode, which fills all four active site subpockets. Herein, we describe the NMR-derived fragment-to-hit pipeline and its application for the development of promising starting points for inhibitors of the main protease of SCoV2.

Nitrogen can be taken up by trees in the form of nitrate, ammonium and amino acids, but the influence of the different forms on tree growth and development is poorly understood in angiosperm species like Populus. We studied the effects of both organic and inorganic forms of nitrogen on growth and wood formation of hybrid aspen trees in experimental conditions that allowed growth under four distinct steady-state nitrogen levels. Increased nitrogen availability had a positive influence on biomass accumulation and the radial dimensions of both xylem vessels and fibers, and a negative influence on wood density. An optimal level of nitrogen availability was identified where increases in biomass accumulation outweighed decreases in wood density. None of these responses depended on the source of nitrogen except for shoot biomass accumulation, which was stimulated more by treatments complemented with nitrate than by ammonium alone or the organic source arginine. The most striking difference between the nitrogen sources was the effect on lignin composition, whereby the abundance of H-type lignin increased only in the presence of nitrate. The differential effect of nitrate is possibly related to the well-known role of nitrate as a signaling compound. RNA-sequencing revealed that while the lignin-biosynthetic genes did not significantly (FDR <0.01) respond to added NO_3- , the expression of several laccases, catalysing lignin polymerization, was dependent on N-availability. These results reveal a unique role of nitrate in wood formation and contribute to the knowledge basis for decision-making in utilizing hybrid aspen as a bioresource.