Green manure crops for low fertility soils

Organic crop production is growing, but crop yields are still below potential. The purpose of our project “Nutrients for higher organic yields (NutHY)” is to increase yields and resource efficiency in organic crop production by optimizing nutrient supply. Growing green manure is an important tool to improve fertilization by biological nitrogen (N) fixation but also by mobilization and release of other nutrients such as phosphorus (P). However, development and performance of green manure are affected by low soil nutrient availability that is often reported as a problem in organic arable farms, especially with regard to P. Poster at DOK-Monte Veritá Conference, 6-11 October, 2019, Congressi Stefano Fanscini, Monte Veritá, Switzerlan

Hyperbolic Hubbard-Stratonovich transformations and bosonisation of granular fermionic systems

The present work consists of two parts. The first part deals with hyperbolic Hubbard-Stratonovich transformations. Such transformations are used to derive non-linear sigma models that describe the low energy behaviour of disordered electron systems. For a long time the mathematical status of hyperbolic Hubbard-Stratonovich transformations of Pruisken-Schäfer type remained unclear. Only recently the two special cases of pseudounitary and pseudoorthogonal symmetry were proven . In this thesis we prove the transformation for a general (essentially semisimple) symmetry group. The proof is descriptive and shows explicitly the connection to the standard Gaussian integrals. In the second part we develop a novel method to bosonise granular fermionic systems. The method is related to the method of coherent states. In particular it is not based on the well known bosonisation of (1+1)-dimensional systems. One approach is to use the colour-flavour transformation to transform the Grassmann path integral representation of a grand canonical partition function in a way that allows to eliminate the Grassmann variables. The result is a path integral in generalised coherent states with special boundary conditions

Catch Crops in Organic Farming Systems without Livestock Husbandry - Simulations with the DAISY model

This paper presents simulations of the soil-plant-atmosphere model DAISY based on an organic crop rotation with incorporation of different catch crops following pea as a leguminous cash crop. Special emphasise was put on the simulation of N-mineralisation/-immobilisation and of soil microbial biomass N. The DAISY model was able to simulate soil mineral N and soil microbial biomass N after soil incorporation of catch crop plant residues to some extend. Several processes need further attention and may be integrated into the DAISY model: (1) soil tillage induced mobilisation of organic material including considerable amounts of organic N, (2) winter killing of sensitive plant species and varieties, (3) decomposition of plant residues at the soil surface as occurring after winter killing, (4) decomposition of easily decomposable plant residues at low temperatures, (5) soil microbial residues as an organic pool temporarily protected against turnover. Furthermore, reliable criteria for the subdivision of green plant residues into an easily decomposable pool and a more recalcitrant pool have to be developed

Effects of Different Lengths of a Nucleic Acid Binding Region and Bound Nucleic Acids on the Phase Behavior and Purification Process of HBcAg Virus-Like Particles

Virus-like particles (VLPs) are macromolecular structures with great potential as vehicles for the targeted administration of functional molecules. Loaded with nucleic acids, VLPs are a promising approach for nanocarriers needed for gene therapy. There is broad knowledge of the manufacturing of the truncated wild-type lacking a nucleic acid binding region, which is mainly being investigated for vaccine applications. Whereas for their potential application as a nanocarrier for gene therapy, hepatitis B core antigen (HBcAg) VLPs with a nucleic acid binding region for efficient cargo-loading are being investigated. VLP structure, loading, and phase behavior are of central importance to their therapeutic efficacy and thereby considerably affecting the production process. Therefore, HBcAg VLPs with different lengths of the nucleic acid binding region were produced in E. coli. VLP attributes such as size, zeta potential, and loading with host cell-derived nucleic acids were evaluated. Capsid’s size and zeta potential of the VLP constructs did not differ remarkably, whereas the analysis of the loading with host cell-derived nucleic acids revealed strong differences in the binding of host cell-derived nucleic acids dependent on the length of the binding region of the constructs, with a non-linear correlation but a two-zone behavior. Moreover, the phase behavior and purification process of the HBcAg VLPs as a function of the liquid phase conditions and the presence of host cell-derived nucleic acids were investigated. Selective VLP precipitation using ammonium sulfate was scarcely affected by the encapsulated nucleic acids. However, the disassembly reaction, which is crucial for structure homogeneity, separation of encapsulated impurities, and effective loading of the VLPs with therapeutic nucleic acids, was affected both by the studied liquid phase conditions, varying pH and concentration of reducing agents, and the different VLP constructs and amount of bound nucleic acids, respectively. Thereby, capsid-stabilizing effects of the bound nucleic acids and capsid-destabilizing effects of the nucleic acid binding region were observed, following the two-zone behavior of the construct’s loading, and a resulting correlation between the capsid stability and disassembly yields could be derived

Development of methods for the production and purification of streptavidin from Streptomyces avidinii and heterologous hosts

Müller J. Development of methods for the production and purification of streptavidin from Streptomyces avidinii and heterologous hosts. Bielefeld: Universität Bielefeld; 2016.The biotin-binding protein streptavidin (SAV) is applied in a large variety of methods due to its extremely high affinity to the vitamin biotin, ranging from protein purification and use as a bioinsecticide to tumor staining. However, common processes for the production and purification of the protein show a diverse range of serious deficiencies like low productivities and concentrations of product, the application of the toxic and flammable organic solvent methanol in heterologous production, and labile, expensive gel materials used for affinity chromatography of SAV. Hence, this project focused on the development of advanced strategies for the production and purification of the protein, targeting an economical and sustainable supply of SAV for common applications. Optimization of process conditions for the natural producer Streptomyces avidinii led to a highly ecological bioreactor fed-batch process based on the constant feeding of glucose. Reproducibly yielding 39.2 µM of SAV in 14 days (114 nM/h), this strategy surpassed previously reported concentrations for this host by the factor 12.7. Continuous cultivation indicated that even higher productivities can be achieved at dilution rates in the range of 0.2 1/h. A systematic variation of the rotary frequency of the stirrer revealed shear-sensitive properties of the streptomycete. Moreover, shake flask studies led to a selection of efficient strategies for the control of morphology. Heterologous expression of the SAV gene was analyzed applying three hosts: the Gram-negative bacterium Escherichia coli and the yeasts Pichia pastoris and Hansenula polymorpha. For E. coli, broad optimization of process conditions allowed a more holistic view of the production of SAV by this biotechnological model bacterium. Application of the periplasmic ’leaky mutant’ JW1667-5 (Δlpp-752::kan), the constitutive β-lactamase promoter from E. coli, the bglA-leader peptide from Bacillus amyloliquefaciens, and addition of the non-ionic surfactant Triton led to the secretion of more than 90 % of SAV to the medium. Bioreactor fed-batch fermentation at 30 ° C resulted in 2.6 ±0.2 µM of highly bioactive SAV in 40 h (65.2 nM/h), exceeding all reference concentrations for the soluble, secretory production of full-length SAV by E. coli. For P. pastoris, a new strategy for the methanol-free production of a shortened form of SAV based on the constitutive GAP promoter was developed. This study demonstrates for the first time that SAV can be produced in a growth-associated manner by the biotin auxotrophic yeast, obviating the need for an induction by methanol. Productivity was greatly enhanced by successive cooling and acidification throughout the cultivation. Model-based evaluation of the optimized conditions in the bioreactor revealed that the majority of product accumulated in the late phase of fermentation at diminishing growth rates. This is atypical for GAP promoter-based production processes, since the activity of PGAP is usually known to be positively correlated to the growth rate of the host. The final fed-batch process led to 4.2±0.1 µM of SAV in 72 h (57.8 nM/h). Compared to literature, the proportion of biotin-blocked binding sites Qblocked was lowered from 20 % to 0±2 %. The yeast H. polymorpha has not been used for the production of SAV prior to this project. Establishing this host for the production of SAV included genetic aspects, process development, and up-scaling to the bioreactor. Like observed for E. coli, cultivation at 30 instead of 37 ° C turned out to be beneficial, resembling typical conditions for the natural producer S. avidinii. Application of the FMD promoter and a full-length SAV gene allowed the accumulation of SAV in the absence of methanol (’derepression’). However, production was enhanced upon induction by the organic solvent. A three-stage process, consisting of a batch phase and two phases of DO-stat feeding of glucose and methanol, respectively, yielded 11.4±0.2 µM of SAV in 216 h (52.5 nM/h). These properties resemble reference results reported for the methanol-based expression of a full-length SAV gene using P. pastoris. Remarkably, Qblocked was as low as 1.1±3.8 %. In addition to these studies, a novel fluorometric assay was developed for the rapid detection of biotin-blocked binding sites of SAV based on the heat-based displacement of biotin from the binding pocket. Model-based evaluation of association and dissociation courses led to conditions allowing the detection of all biotin-blocked binding sites in a sample independent of the degree of biotin saturation. This new strategy facilitates analysis of the bioactivity and host toxicity of SAV during heterologous production. Furthermore, it may simplify the development of methods for the non-denaturing separation of SAV and biotin by revealing changes of the overall concentration of SAV rather than the concentration of biotin-free binding sites. To demonstrate the latter feature, the assay was used for the development of methods for the partial recovery of biotin-blocked binding sites of SAV by hydrogen peroxide treatment and UV radiation. Incubation in the presence of hydrogen peroxide at elevated temperatures resulted in the recovery of up to 30 % of biotin-blocked binding sites of a completely biotin-saturated sample of SAV without major effects on the overall bioactivity of SAV. Purification of SAV was studied by aqueous two-phase extraction, thermal inactivation of contaminating proteins, diafiltration, dialysis, and ammonium sulfate precipitation. The efficiency of the methods was assessed by SDS-PAGE analysis and determination of total protein. The results indicate that for many applications the direct use of crude supernatants or SAV purified by these simple and inexpensive procedures may be sufficient, whereas purification by chromatography may be necessary if high product purities are required

Ljubljanska dolenjščina: potrditev Riglerjeve teorije

Jurij Japelj provided data that clearly shows that the eighteenth-century Ljubljana dialect used the reflex u: for circumflexed o: and neoacute-stressed o with early lengthening, which agrees with Jakob Rigler’s theory of the historical basis of standard Slovenian phonology.Jurij Japelj navaja podatek, iz katerega je očitno, da je ljubljanščina 18. stoletja za cirkumflektirani in zgodaj podaljšani novoakutirani etimološki o: imela odraz u:, kar je skladno s teorijo Jakoba Riglerja o zgodovinski osnovi slovenskega knjižnega glasovja