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Application of Basidiomycota-derived biocatalysts in organic synthesis
(2026) Nikitenkova, Valeriia
The increasing demand for sustainable and selective methods of organic synthesis drives the replacement of traditional energy-intensive processes often based on toxic chemical reagents. Biocatalysis offers an attractive alternative that allows efficient transformations to be carried out under mild and environmentally friendly conditions. White-rot fungi represent a particularly promising source of such biocatalysts, as approaches based on these fungi exhibit high enzyme stability and unique enzymatic pathways compared to other biocatalytic methods based on bacteria or yeasts. Their non-toxic nature, along with straightforward application and accessibility, makes them attractive for various biotechnological processes. Nevertheless, the practical application of fungi as biocatalysts, including both growing cultures and storable lyophilized mycelium, remains insufficiently explored in preparative organic synthesis. The present dissertation focuses on the disclosing of biocatalytic potential of the white-rot fungus Bjerkandera adusta, chosen for its non-toxic nature, rich enzymatic profile, and simple cultivation on inexpensive substrates. The work investigates the biocatalytic potential of both, the growing culture and the lyophilized mycelium with the aim of developing practical, selective, and green preparative approaches for the transformation of organic compounds. Particular attention is given to the ability of B. adusta to carry out oxidation and reduction reactions under mild and environmentally friendly conditions. Lyophilized mycelium of B. adusta was shown to catalyze clean and selective oxidations of aromatic alcohols to the corresponding aldehydes under “on-water-on-air” conditions. The catalytic activity observed in the lyophilized mycelium was shown to be associated with the presence of aryl-alcohol oxidases. High conversion rates without overoxidation were achieved under mild conditions, and the lyophilisate retained its oxidative activity over extended storage periods, highlighting its practical value for further applications. The oxidative potential of the lyophilisate of B. adusta was further demonstrated through the selective conversion of α,β-unsaturatedalcohols into valuable (E)-allylic aldehydes. The addition of small amounts of organic co-solvents enhanced substrate conversion while maintaining high chemoselectivity. Notably, B. adusta also mediated the isomerization of (Z)-2-nonenal to the corresponding (E)-diastereomer without further carbonyl group oxidation or CC-double bond reduction, which is rarely achieved under such conditions. Comparative experiments with lyophilisates of Pleurotus species confirmed the special catalytic efficiency of B. adusta in these reactions. In contrast, growing cultures of B. adusta exhibited reductive activity, selectively converting anthranilic acid into 2-aminobenzaldehyde while completely suppressing overreduction to the corresponding alcohol. This transformation proceeds in aqueous aerobic conditions and displays strict regioselectivity, with only the o-isomer accepted as a substrate.
Physiologische Untersuchungen zur reproduktiven Kältetoleranz beitragender Mechanismen bei Sorghum (Sorghum bicolor L. Moench)
(2026-02) Neitzert, Luisa
Die aus den semiariden Regionen Afrikas stammende Sorghumhirse (Sorghum bicolor) birgt ein hohes Potential für die Ausweitung des Anbaus in die gemäßigten Breiten: eine hohe Wasser- und Nährstoffnutzungseffizienz, vielseitige Nutzungsmöglichkeiten, Resistenz gegen den Maiswurzelbohrer und ein mit Mais vergleichbares Ertragspotenzial mit deutlichen Vorteilen unter Trockenstress. Für eine Etablierung in den gemäßigten Regionen Europas stellt die Kälteempfindlichkeit im reproduktiven Stadium eine zentrale Hürde dar. Daraus ergibt sich ein klarer Forschungs- und Züchtungsbedarf, der ein physiologisches Verständnis der zugrundeliegenden Mechanismen voraussetzt. Es konnte bestätigt werden, dass die frühe reproduktive Phase ist bei Sorghumhirse das empfindlichste Zeitfenster gegenüber Kälte. Ein zentrales Ergebnis ist zudem die Relativierung der in der Literatur beschriebenen, durch Kälte eingeschränkten Pollenfertilität mit einhergehenden Ertragsverlusten. Entgegen früherer Annahmen gingen bei den untersuchten Genotypen Ertragsminderungen nicht zwingend mit verringerter Pollenfertilität einher. Zusätzliche Bestäubungsexperimente zeigten, dass die männliche Komponente nicht der erstlimitierende Faktor ist. Diese Ergebnisse sprechen dafür, dass Kälte den Ertrag nicht primär über eine eingeschränkte Pollenfertilität begrenzt wir, sondern dass das weibliche Blütenorgan vermutlich stärker als bisher angenommen zur kälteinduzierten Ertragsdepression beitragen könnte. Auf hormoneller Ebene konnte außerdem gezeigt werden, dass der kältetolerante Genotyp in der Lage ist, Abscisinsäure unter Kältestress niedrig zu halten, während der empfindliche Genotyp höhere Konzentrationen aufweist. Im Unterschied zu Reis lässt sich der dort postulierte Mechanismus, das hohe Abscisinsäure-Gehalte und ein zu geringer Pool an bioaktiven Gibberellinen zu einer gestörten Pollenentwicklung führen, für Sorghum nicht bestätigen. Zusätzlich wurde ein antagonistischer Zusammenhang zwischen Gibberellinsäure und Jasmonsäure beobachtet, welcher durch Kältestress nicht beeinträchtigt wurde. Reproduktive Kältetoleranz ist ein komplexes, polygenes Merkmal. Hinsichtlich der Vererbung zeigen F1-Hybriden keine überwiegenden maternalen oder paternalen Effekte, was für eine biparentale Vererbung spricht und somit gegen die Möglichkeit, Toleranz ausschließlich in einem heterotischen Pool zu fixieren. Zusammenfassend leistet diese Arbeit einen Beitrag zum besseren Verständnis der reproduktiven Kältetoleranz in Sorghum bicolor. Des Weiteren eröffnen sie Perspektiven für künftige Forschungs- und Züchtungsarbeiten hinsichtlich kältetoleranter und ertragsstabiler Sorghumsorten für die Ausweitung des Anbaus in gemäßigte Breiten, insbesondere vor dem Hintergrund globaler Ernährungs- und Ressourcenherausforderungen.
Effects of breeding for short-tailedness in sheep on parameters of reproduction and lamb development
(2025) Hümmelchen, Hannah; Wagner, Henrik; Brügemann, Kerstin; König, Sven; Wehrend, Axel
Background: Sheep's tail docking is a widespread practice, which is banned or critically discussed in some countries to improve animal welfare. Objective: The aim was to determine the influence of breeding for short-tailedness (ST) or long-tailedness (LT) in sheep on the development of reproduction parameters and lamb performance. Method: One hundred forty-nine ewes were mated with four rams according to tail length. Pregnancy and pregnancy loss rates were calculated. During pregnancy, the progesterone levels (P4) of the ewes were measured. The weight and length of the 254 lambs were recorded up to 14 weeks of life. Litter size, placenta weight, sex, stillbirths, vitality, morbidity and mortality of the lambs were also documented. Results: No significant differences were found for P4 and placental weight for the two mating groups (ST and LT). Although the pregnancy rate for ST was slightly lower (75.71%) than for LT (87.34%), there was only a low significant difference (p = 0.07). The sex distribution was 61 (48.80%) male and 64 (51.20%) female lambs in the ST group and 67 (51.94%) male and 62 (48.06%) female lambs in the LT group. The twinning rate was not significantly different (ST 75.20%; LT 75.97%), and no significant difference was found in the average body length and vitality of the lambs. However, LT lambs showed better weight gains that were marginally significant (p = 0.09). Conclusion: This study found no evidence that reproductive parameters or lamb performance were affected by selective breeding based on tail length.
Pig tail length is associated with the prevalence of tail malformations but not with inflammation of the tail
(2025) Egerer, Christiane; Gerhards, Katharina; Becker, Sabrina; Engel, Petra; König, Sven; Reiner, Gerald
Evaluating hydrological model performance using varying amounts of participatory monitoring water level data
(2025) Mitze, Fabian; Jacobs, Suzanne Robin; Breuer, Lutz; Zeballos, Jazmin Campos; Weeser, Björn
In the context of participatory monitoring projects in hydrology, the collection of water level data by laypersons is used as a simple and cost-effective alternative to automatic water level sensors, especially in poorly gauged catchments in remote areas of countries in the Global South. Such data can be used for the development of hydrological models to support water resources management. However, a common problem with participatory monitoring approaches is the irregularity of data collection and its decreasing frequency over time. Determining the amount and timing of data collection required for satisfactory model calibration is critical. To investigate this further, we examined daily water levels from a four-year project in western Kenya. We set up scenarios that represented datasets of different lengths and seasonal starting points for measurements. These scenarios were then used to calibrate a simple rainfall-runoff model. The data were supplemented with satellite data on evapotranspiration to improve the simulated water balance. The model runs were filtered using a water balance filter, and the Kling-Gupta-Efficiency (KGE) was used to compare model efficiencies. While a single month of water level data collected during the rainy seasons was sufficient to achieve good model performance (KGE ≥ 0.75), several months of data were required for simulations starting in the dry seasons. Similar results were found for the validation period, with lower overall model performance (KGE ≥ 0.6). Water level data collected during high flows generally led to an improvement in model performance compared to data collected during low flows. However, after a certain threshold, more water level data did not lead to further substantial model improvement. Based on the analysis of different datasets, this study demonstrated that short-term participatory monitoring programs that collect water level data during the wet season have the potential to provide sufficient input to calibrate a hydrological model.