Danish Technological Institute

In commercial microalgae cultivations with high cell density, individual cells are exposed to rapid shifts in the illumination conditions, due to a limited light penetration combined with the fluid circulation patterns. The impact of these shifts on the physiological state of the cells must be precisely assessed, to obtain reliable predictions of the productivity of the cultivation, and to evaluate the degree of light utilization and the illumination needs. To this end, in this study we present a first-principles dynamic model that encompasses the processes of photon capture, electron transport, photoinhibition, pH regulation and carbon fixation, at the molecular level. These processes are characterized in terms of several cellular rates, including electron transport, photodamage, photorespiration, pH variation in stroma and lumen, ATP and NADPH formation and consumption, carbon fixation, and O 2 and CO 2 exchange across the cell membrane. The rates, grounded it a state-of-the-art understanding of the photosynthetic machinery in the chloroplast, are incorporated into a system of 10 differential equations, which yields macroscopic predictions of oxygen production, carbon consumption and biomass growth rate. The computational simulation showed results in significant agreement with multiple literature sources, thereby validating the mechanistic modelling framework. The resulting model, based on a characterization of fundamental photosynthetic components, is therefore broadly applicable, and can be adapted to different microalgae species. • A dynamic mechanistic model for photosynthesis-associated processes has been developed. • The model encompasses photon capture, electron transport, photoinhibition, pH regulation and carbon fixation. • Literature-based parametrization led to results in good agreement with available empirical data.

ABSTRACTUnsustainable soil management, climate change, and land degradation jeopardize soil biodiversity and soil‐mediated ecosystem functions. Although the transition from conventional to organic agriculture has been proposed as a potential solution to alleviate these pressures, there is limited evidence of its effectiveness in enhancing belowground biodiversity across different biogeographical regions, climates, and land degradation levels. In this study, we holistically assessed the status of soil biodiversity, from microorganisms to meso‐ and macrofauna, in agroecosystems distributed across four continents. We identified the primary environmental community composition drivers and assessed the effects of the transition from conventional to organic management (no chemical inputs) on soil ecology. Our findings highlight the mean temperature and precipitation of the warmest and coldest quarters of the year, aridity, pH, and soil texture as the primary drivers of the different soil biodiversity components. Overall, organic farming has a significant but small impact on soil biodiversity compared to the other community drivers. On top of that, the results demonstrate the importance of a regional‐specific context for a future generalized transition towards organic soil management. Specifically, under the most arid conditions in our study, organic management showed potential to buffer biodiversity loss in highly degraded soils, with a significant increase in diversity for prokaryotes and protists compared to conventionally managed soils. Therefore, the combination of a global and, simultaneously, regional‐specific approach supports the hypothesis that a shift towards organic agriculture would maximize its beneficial impact on belowground diversity in highly degraded soils under arid conditions over the coming years, being a crucial tool to increase resilience and adaptation to global change for agriculture.

Plastic accumulation has become a major global concern due to the lack of efficient and environmentally friendly strategies to manage the end-of-life of these materials. Among the most used families of plastics is polyurethane (PU), which is valued for its versatility and low production cost. A promising strategy to address the end-of-life challenges of PU is employing efficient PU-degrading enzymes. Notably, an extracellular lipase from the I.3 family originating from Pseudomonas sp. MIS38 has shown significant promise in this regard. In this study, we investigated the enzyme’s capability to hydrolyze a PU fragment. Employing QM/MM computational methodologies, we studied the hydrolysis mechanism of MIS38 lipase and found it to follow the prototypical serine esterase mechanism involving acylation and deacylation stages. The rate-limiting step occurred between the formation of the acyl-enzyme intermediate and the formation of the second tetrahedral intermediate. The Gibbs activation barrier for this step was 19.67 kcal·mol–1, confirming the lipase’s potential to biodegrade PU efficiently. More importantly, we observed that the enzyme preferentially cleaved the C–N bond instead of the C–O bond. This preference was due to the arrangement of the active site and the substrate, which made C–N the more favorable cleavable site. Furthermore, we find that the C–O group is not a suitable cleavable bond due to steric hindrances. This study suggests that the mechanism of urethane bond hydrolysis is more complex than currently assumed because bond cleavage is context-dependent and may differ depending on the enzyme and the substrate.

Abstract Trees grown in outdoor animal farming systems may provide green biomass as a potential feed source, remove nutrients through uptake in biomass and, hence, reduce the risk of nutrient loss. We investigated the effects of harvest time during the growing season in three field experiments with willow and one with poplar, harvested either during the previous winter or one year earlier. Green biomass including shoots and leaves was either harvested 24th June or 24th September 2021. Regrowth in the subsequent growing season was measured in November 2022 in two of the willow experiments. Biomass yield and removal of N and P with harvested biomass was measured. The nutrient concentration in the biomass decreased significantly from June to September whereas the yield of dry matter (DM), N and P increased. For example, for the willow clone Tordis harvested the previous winter, the N concentration in DM decreased from 2.86% to 1.27% (corresponding to 17.9 and 7,9% crude protein in DM), whereas the DM yield increased from 0.9 to 8.5 Mg ha−1, and removal of nutrients increased from 32 to 114 kg N ha−1 and from 3.8 to 16.5 kg P ha−1. Regrowth of willow was negatively affected by harvest during the growing season; total DM yield over a full harvest rotation was reduced 46–48% and 34–40% when harvesting in June or September compared to no harvest during the growing season. Optimal harvest strategy in willow and poplar may differ whether the purpose is feed production, nutrient removal or maximum DM production.

This study analyzed the polyphenol composition in fiveCannabis sativaL. varieties (Finola, Ferimon, Fedora 17, Futura 75, and Santhica) across plant parts (buds, leaves, and stems) and growth stages (June-September 2022). Microflow LC-MS and spectrophotometry screened 25 polyphenols, quantifying 17 (flavan-3-ols, flavanols, and flavanones). Seasonal dynamics significantly influenced all compound classes, with the polyphenol content decreasing during bud development. Buds exhibited the highest diversity and abundance compared to leaves/stems. Distinct varietal profiles emerged: Finola (early maturing) showed peak bud polyphenols in June, while Santhica (late-maturing) peaked in September. Flavan-3-ol characterization identified catechin as the dominant monomer, followed by epicatechin and procyanidin B1. These findings highlight the impact of harvest timing and cultivar selection on bioactive compound profiles, offering insights into optimizing hemp cultivation and valorizing polyphenols in food, pharmaceutical, or agricultural industries.