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The cellulose-water interface is a dynamic environment mostly dominated by interactions between water molecules and hydroxyl groups protruding from the top layer of the polysaccharide chains. This interface has attracted increasing interest within the context of hydrolysis with glycosyl hydrolases, and studies on the role of tightly bound and free water has emerged. At the molecular level, cellulose-bound water has been considered important to allow enzymatic hydrolysis at industrial relevant conditions, i.e. at high dry matter (HDM) contents. In the presence of lytic polysaccharide monooxygenase enzymes, the hydrolysis can with effective yields be run at well beyond the dry matter limit previously set by the 1st generation of enzyme preparations lacking LPMOs. The oxidative cleavage of the cellulose chain performed by LPMOs allow a higher level of synergism with GH in terms of accessibility of the cellulose surface. In this work, we studied how cellulose oxidation by LPMO increases the cellulose-water interaction and the impact of this on cellulose saccharification. Low-field NMR, water constraint and enzyme kinetics at high dry matter contents were used to characterize the cellulose-water interaction and its implications in enzymatic cellulose hydrolysis.

Wood-feeding termites effectively degrade plant biomass through enzymatic degradation. Despite their high efficiencies, however, individual glycoside hydrolases isolated from termites and their symbionts exhibit anomalously low effectiveness in lignocellulose degradation, suggesting hereto unknown enzymatic activities in their digestome. Herein, we demonstrate that an ancient redox-active enzyme encoded by the lower termite Coptotermes gestroi, a Cu/Zn superoxide dismutase (CgSOD-1), plays a previously unknown role in plant biomass degradation. We show that CgSOD-1 transcripts and peptides are up-regulated in response to an increased level of lignocellulose recalcitrance and that CgSOD-1 localizes in the lumen of the fore- and midguts of C. gestroi together with termite main cellulase, CgEG-1-GH9. CgSOD-1 boosts the saccharification of polysaccharides by CgEG-1-GH9. We show that the boosting effect of CgSOD-1 involves an oxidative mechanism of action in which CgSOD-1 generates reactive oxygen species that subsequently cleave the polysaccharide. SOD-type enzymes constitute a new addition to the growing family of oxidases, ones which are up-regulated when exposed to recalcitrant polysaccharides, and that are used by Nature for biomass degradation.

The bleach plant of a pulp and paper (P&P) mill presents a major source of wastewater containing toxic organic matter characterized as chemical oxygen demand (COD). Due to their high oxidizing power, oxidoreductases hold promise to be a key solution for the removal of dissolved organic material. Here, four oxidoreductases from different enzyme families were selected to treat bleach plant effluents. Haloperoxidase treatment of the final effluent resulted in the highest levels of decolorization (71%) and reduction of aromatic compounds (36%). Using single compound analysis, 27 low molecular weight compounds were found to be persistent throughout the wastewater treatment process and, therefore, classified as hard COD. The tested enzymes efficiently removed several of the identified COD compounds. Hence, this study suggests that the application of oxidoreductases will serve as an environmental-friendly solution for reducing waste from P&P production.

Processing of lignocellulosic biomass is complex due to the heterogeneity of the substrate, but also due to lengthy unit operations, which complicates process control including for enzymatic saccharification. Methods for predicting enzymatic saccharification yield based on the properties of the pretreated biomass would be advantageous to process optimization and control. Biomass-water interaction measurements provide a method for quickly predicting biomass recalcitrance. Correlating water retention value (WRV) and enzymatic saccharification yield (ESY) on pretreated biomass has shown promise, especially when assessing only single biomass types pretreated with one specific chemistry. However, with comparisons between different types of biomasses, predictive powers have been low. We investigate the effect of pretreatment chemistry on the predictive power of WRV, when keeping the biomass static. Wheat straw was pretreated with dilute acid, hydrothermal, or alkaline chemistries at five different temperatures. Furthermore, low field nuclear magnetic resonance was used to measure water constraint in the pretreated materials, to better understand how biomass-water interactions change with pretreatment severity and chemistry. We show that the correlation of WRV and ESY is highly pretreatment dependent, while WRV strongly predicts ESY within each pretreatment chemistry. While ESY and WRV correlated under all chemistries, the direction of the correlations were divergent, suggesting a more complex interplay between recalcitrance and biomass-water interactions. Using T2 relaxation profiles, reductions in hemicellulose composition was related to the decrease in size of the most constrained water population present in the pretreated biomasses for all chemistries, suggesting a new identification of this population of constrained water.

Lytic polysaccharide monooxygenases (LPMOs) are copper‐containing enzymes capable of oxidizing crystalline cellulose which have large practical application in the process of refining biomass. The catalytic mechanism of LPMOs still remains debated despite several proposed reaction mechanisms. Here, we report a long‐lived intermediate (t½ = 6 ‐ 8 minutes) observed in an LPMO from Thermoascus aurantiacus (TaLPMO9A). The intermediate with a strong absorption around 420 nm is formed when reduced LPMO‐Cu(I) reacts with sub‐equimolar amounts of H2O2. UV‐vis absorption spectroscopy, electron paramagnetic resonance, resonance Raman and stopped‐flow spectroscopy suggest that the observed long‐lived intermediate involves the copper center and a nearby tyrosine (Tyr175). Additionally, activity assays in the presence of sub‐equimolar amounts of H2O2 showed an increase in the LPMO oxidation of phosphoric acid swollen cellulose. Accordingly, this suggests that the long‐lived copper‐dependent intermediate could be part of the catalytic mechanism for LPMOs. The observed intermediate offers a new perspective into the oxidative reaction mechanism of TaLPMO9A and hence for the biomass oxidation and the reactivity of copper in biological systems.

Photobiocatalysis holds great promise toward the development of sustainable and environmentally friendly processes, harnessing light to drive biocatalytic reactions. However, photobiocatalysis at the interface of insoluble substrates, such as cellulose, has not been studied in much detail. In this context, the catalytic enhancement of lytic polysaccharide monooxygenases (LPMOs) by light is of great interest to the biorefinery field due to their capacity to oxidatively cleave such recalcitrant polysaccharides which can facilitate the degradation of lignocellulose. It has previously been reported that light-driven LPMO reactions have a huge catalytic potential, but effective continuous illumination in reactors may be challenging. Therefore, we investigated the impact of intermittent illumination. We show that illumination intervals as short as 1 s/min enable LPMO catalysis on phosphoric acid-swollen cellulose (PASC) to the same level as continuous illumination. Additionally, time-resolved measurements indicate that reductant depletion, and not enzyme inactivation, limits light-driven LPMO reactions. This study shows that a 60-fold reduction in illumination time enhances LPMO catalysis while protecting reaction elements, e.g., the reductant. Most importantly, the significant enhancement of LPMO catalysis with minimal and intermittent illumination is promising toward an application of photobiocatalytic depolymerization of lignocellulose where shading and light scattering minimize light availability and continuity.

Emissions of greenhouse gases (GHG) are linked to global warming and adverse climate changes. Meeting the needs of the increasing number of people on the planet presents a challenge for reducing total GHG burden. A further challenge may be the size of the average person on the planet and the increasing number of people with excess body weight. We used data on GHG emissions from various sources and estimated that obesity is associated with ~20% greater GHG emissions compared with the normal-weight state. On a global scale, obesity contributes to an extra GHG emissions of ~49 megatons per year of CO2 equivalent (CO2eq) from oxidative metabolism due to greater metabolic demands, ~361 megatons per year of CO2eq from food production processes due to increased food intake, and ~290 megatons per year of CO2eq from automobile and air transportation due to greater body weight. Therefore, the total impact of obesity may be extra emissions of ~700 megatons per year of CO2eq, which is about 1.6% of worldwide GHG emissions. Inasmuch as obesity is an important contributor to global GHG burden, strategies to reduce its prevalence should prioritize efforts to reduce GHG emissions. Accordingly, reducing obesity may have considerable benefits for both public health and the environment.

Current dietary guidelines advocate more plant-based, sustainable diets on the basis of scientific evidence about diet-health relations but also to address environmental concerns. Here, we critically review the effects of plant-based diets on the prevalence of obesity and other health outcomes. Plant-based diets per se have limited efficacy for the prevention and treatment of obesity, but most have beneficial effects in terms of chronic disease risk. However, with the considerable possibilities of translating plant-based diets into various types of dietary patterns, our analysis suggests that potential adverse health effects should also be considered in relation to vulnerable groups of the population. A transition to more plant-based diets may exert beneficial effects on the environment, but is unlikely to affect obesity, and may also have adverse health effects if this change is made without careful consideration of the nutritional needs of the individual relative to the adequacy of the dietary intake.

Photobiocatalysis holds great promise toward the development of sustainable and environmentally friendly processes, harnessing light to drive biocatalytic reactions. However, photobiocatalysis at the interface of insoluble substrates, such as cellulose, has not been studied in much detail. In this context, the catalytic enhancement of lytic polysaccharide monooxygenases (LPMOs) by light is of great interest to the biorefinery field due to their capacity to oxidatively cleave such recalcitrant polysaccharides which can facilitate the degradation of lignocellulose. It has previously been reported that light-driven LPMO reactions have a huge catalytic potential, but effective continuous illumination in reactors may be challenging. Therefore, we investigated the impact of intermittent illumination. We show that illumination intervals as short as 1 s/min enable LPMO catalysis on phosphoric acid-swollen cellulose (PASC) to the same level as continuous illumination. Additionally, time-resolved measurements indicate that reductant depletion, and not enzyme inactivation, limits light-driven LPMO reactions. This study shows that a 60-fold reduction in illumination time enhances LPMO catalysis while protecting reaction elements, e.g. the reductant. Most importantly, the significant enhancement of LPMO catalysis with minimal and intermittent illumination is promising toward an application of photobiocatalytic depolymerization of lignocellulose where shading and light scattering minimize light availability and continuity., SCOPUS: ar.j, info:eu-repo/semantics/published

Agricultural residues, such as straw, offer an opportunity to produce biofuels and chemicals in biorefineries without compromising food production. The ideal “dual-purpose cultivar” would have high yield of grain and straw. In addition, the straw should be easy to process in a biorefinery: It should have good degradability, high concentration of carbohydrates, and low concentration of ash. Nitrogen (N) is an essential nutrient important for plant growth, crop yield and grain quality. However, N production and application comes with a high cost and high environmental footprint. The N application should consequently be based on an economical optimum. Limited knowledge exists on how N application affects the potential of straw for biorefining, for example, straw yield and quality. This study, conducted over three cropping seasons, investigated the effect of N supply on the biorefining potential and included 14 wheat cultivars and one triticale cultivar. The N supply directly affected the yield of straw and grain. In addition, the protein concentration in grain and straw increased, but the composition of the straw with respect to carbohydrates and lignin was largely unaffected by N supply. The only significant change was a lower silicon concentration at increasing N application rate, which could be beneficial for lignin valorization in biorefineries. Likely due to the negligible changes in cell wall composition, the effect of N application rate on straw degradability was not significant. N application should therefore primarily be optimized with respect to grain quality and overall yield of grain and straw. Differences between cultivars were also minor with respect to their performance in a biorefinery process. From a breeding and agronomic perspective, focus should therefore be put on maximizing the biomass output from the field, that is, selecting the cultivar with highest grain and straw yield and optimizing the application of fertilizer to get optimum N use effic

Hydrothermal pretreatment is commonly used for enhancing enzymatic hydrolysis of lignocellulosics. Spruce and wheat straw were pretreated with increasing severity and lignin characteristics were analysed. The effect of enzymatically isolated lignin on the hydrolysis of Avicel and the adsorption of a cellobiohydrolase onto lignin was measured. Non-pretreated lignins had only a minor effect on Avicel hydrolysis. The structural changes in lignin accompanying hydrothermal pretreatment were associated with increased binding and inactivation of the cellulase on the lignin surface. The inhibitory effect was more pronounced in spruce than in wheat straw lignin. However, similar pretreatment severities caused similar levels of inhibition in Avicel hydrolysis for both biomass sources. The combined severity factor of the pretreatment correlated well with the inhibitory effect of lignin.

Herein is detailed a biofuel composition and a process for the manufacture of a biofuel composition comprising lignin and ethanol as its main combustible components and having total ash below 1% w/w based on total mass of dry matter in the biofuel composition.

Briquetting of plant biomass with low bulk density is an advantage for handling, transport, and storage of the material, and heating of the biomass prior to the briquetting facilitates the densification process and improves the physical properties of the briquettes. This study investigates the effects of preheating prior to briquetting of wheat straw (WS) on subsequent hydrothermal pretreatment and enzymatic conversion to fermentable sugars. WS (11% moisture content) was densified to briquettes under different conditions; without preheating or with preheating at 75 or 125°C for either 5 or 10 min. Subsequent hydrothermal pretreatment was done for both un-briquetted WS and for briquettes. Enzymatic saccharification was afterwards performed for all samples. The results showed that as expected, nonpretreated WS briquettes gave very low sugar yields (22–29% of the cellulose content), even though preheating at 125°C prior to briquetting (without pretreatment) improved sugar yields somewhat. When combined with pretreatment, briquetting with preheating showed neutral or negative effects on sugar yield. This result suggests that moderate preheating (75°C for 5 min) before briquetting improved bulk density and compressive resistance of briquettes without impeding subsequent enzymatic conversion. However, excessive preheating (75 or 125°C for 10 min) before briquetting may result in irreversible structural modifications that hinder the interaction between biomass and water during pretreatment, thereby decreasing the accessibility of cellulose to enzymatic saccharification.