60 https://www.uni-bremen.de/en/roggatz/research-1 research to dynamical ecochemestry on biofilms, carbon sequestration in the ocean and microorganism interaction on interfaces en University of Bremen Wed, 13 May 2026 20:56:09 +0200 Wed, 13 May 2026 20:56:09 +0200 University of Bremen content-719538 Thu, 02 Apr 2026 10:46:38 +0200 https://www.uni-bremen.de/en/roggatz/research-1#c719538 <p>Communities of photosynthetic and nutrient-degrading microorganisms are of fundamental importance to life on Earth. They rely on chemical interactions via a range of specific molecules to regulate their interactions, “communicate,” and function efficiently. Microalgae-bacteria communities in aquatic systems share microhabitats where abiotic conditions fluctuate significantly on a daily cycle, as the interplay of photosynthesis and respiration leads to strong gradients in pH and oxygen levels.  Such abiotic conditions can impair communication by altering the molecules and thereby disrupting the associated interactions, as recent studies by the team on macroorganisms have shown.</p> <p>The DIALMOD project investigates the temporal and spatial dynamics of chemical communication in marine biofilms composed of diatoms and bacteria. By combining biological, chemical-analytical, and computational methods for high-resolution analysis, the project aims to determine whether there is a chemical clock that controls interactions within marine communities.</p> Content content-719541 Tue, 07 Apr 2026 10:49:04 +0200 https://www.uni-bremen.de/en/roggatz/research-1#c719541 <p>Soils play a vital role in global and local ecosystem processes, such as the carbon and nitrogen cycles, which can, however, be severely impaired by pesticide contamination. A widely used active ingredient is copper, a heavy metal frequently employed as a fungicide in agriculture. At higher concentrations, copper can be harmful to both terrestrial and aquatic organisms. Therefore, the use of copper in agriculture can have significant impacts on non-target species and ecosystem function. Copper exerts its toxic effects, among other things, through the formation of reactive oxygen species (ROS), which is based on its ability as a redox-active transition metal to accept and donate electrons.<br />The ROSCAR project investigates the interaction of various soil properties relevant to redox processes, such as clay, iron mineral, and organic content, as well as pH, on copper-induced ROS formation, specifically for both conventional and nanoparticle-based copper compounds. This is studied both abiotically in artificial soil media and biotically with regard to the effects on the antioxidant system and the fitness of various soil organisms. The focus is on soil invertebrates such as springtails and enchytraeids, as well as plants that interact directly with the soil and the pollutants it contains, such as copper, through the excretion of root exudates. In addition, interactions with climate-induced environmental stressors, such as elevated temperatures or more frequent drying and wetting cycles, are being investigated, as these can also promote ROS formation.</p> <p>The findings from this project can help bridge the gap between soil and plant protection and also have practical relevance for agriculture, e.g., through recommendations for a more sustainable use of copper-based pesticides that take into account not only the copper compound applied but also the specific soil conditions.</p> <p>ROSCAR is funded by the Central Research Funding Office of the University of Bremen and the German Research Foundation (DFG).</p> Content content-719545 Thu, 02 Apr 2026 10:43:02 +0200 https://www.uni-bremen.de/en/roggatz/research-1#c719545 Content content-719539 Tue, 07 Apr 2026 10:44:24 +0200 https://www.uni-bremen.de/en/roggatz/research-1#c719539 <p>The Transregional Collaborative Research Center <strong>TRR 420 CONCENTRATE</strong>, funded by the German Research Foundation (DFG), investigates how carbon is stored in the ocean. In the marine carbon cycle, sugar molecules (glycans) produced by algae are normally completely broken down by bacteria. Surprisingly, however, large amounts of these compounds are found in the water and even on the seafloor.</p> <p>CONCENTRATE is investigating why some of this carbon escapes degradation and may be sequestered in the ocean over the long term, with direct implications for the climate. Researchers from the University of Bremen, the University of Greifswald, and other partner institutions are studying the underlying processes at all levels, from the molecular to the ecological.</p> <p><strong>Subproject B7 (ACID) – Processes at Microscopic Interfaces</strong></p> <p>Subproject B7 (ACID) of the Dynamic Ecological Chemistry Research Group investigates how environmental conditions at microscopic interfaces influence the degradation of glycans.</p> <p>Many processes in the ocean take place at surfaces, such as on cells or particles. There, active microenvironments are created where microorganisms, enzymes, and substrates are concentrated. At the same time, strong chemical gradients form, for example in oxygen, carbon dioxide, or pH. These conditions change over the course of a day and a year due to processes such as photosynthesis, respiration, or temperature. The central question is how these dynamic conditions influence the activity of CAZymes (carbohydrate-active enzymes). These enzymes control the conversion and degradation of glycans.</p> <p>By combining laboratory experiments and modeling, the research investigates the effects of environmental changes at the microscopic level and how they contribute to carbon storage in the ocean.</p> Content content-719542 Thu, 02 Apr 2026 10:41:50 +0200 https://www.uni-bremen.de/en/roggatz/research-1#c719542 <p><br />Objective: Development of novel magnetic resonance imaging techniques for the in situ characterization of living biofilms and the factors limiting their productivity.</p> <p>Collaborative project within SPP2494 Productive Biofilm Systems with Prof. Sven Kerzenmacher & Dr. Ekkehard Küstermann</p> <p>This project will advance the methodological development of magnetic resonance imaging (MRI) to investigate the spatial distribution of biomass density, mass transport properties, and substrate (O₂ and H₂) and pH gradients in hydrogenotrophic and/or aerophilic biofilms in order to determine their influence on reaction rates and biomass growth.<br />To this end, a C. necator biofilm will be examined via MRI during its growth. Using various MR techniques, both the morphology and the spatially resolved pH, O₂, and H₂ concentrations within the biofilm will be characterized, and locally resolved effective diffusion coefficients will be determined.<br />Furthermore, the influence of quorum-sensing molecules on the architecture and productivity of C. necator biofilms as a function of local pH and oxygen conditions is investigated using the developed magnetic resonance imaging methods.</p> Content