Fritz Hartmann Frimmel

Extracellular polymeric substances were extracted from the bacterial strain Pseudomonas putida and the fungal species Aureobasidium pullulans using three different methods (formaldehyde–NaOH, ethylenediaminetetraacetic acid (EDTA) and cation-exchange-resin). The composition of the extracellular polymeric substances (EPS) was analysed by biochemical and high-resolution solid state ¹³C nuclear magnetic resonance (NMR) spectroscopic methods. The EPS yield was strongly dependent on the extraction method, with the formaldehyde–NaOH method showing the best extraction efficiency. The NMR method revealed that when using the EDTA extraction method, about 40% of the EDTA accumulated in the EPS and that was responsible for the apparent high extraction yields. EPS protein content determined by the NMR method was up to 30% higher than the protein content determined using the biochemical (Lowry) method for P. putida and for A. pullulans. The average protein carbon content determined by the NMR method was approximately 70% of the total carbon content. NMR results could be supported by elemental analysis, which showed a high nitrogen content (~10%) in the EPS. The carbohydrate carbon content detected with both methods in the cell aggregates and the EPS was approximately 20% in each. In this study, quantitative ¹³C cross-polarisation magic angle spinning NMR spectroscopy was conducted on unlabeled cell strains, and EPS and could be used to quantify protein and carbohydrate of different samples.

The impact of selected pollutants on the structure and activity of nitrifying bacterial populations within fixed bed biofilm reactors was examined. Clofibrinic acid and ibuprofen as pharmaceutically active compounds were added to a synthetic wastewater fed to the biofilm reactors and the concentrations of chloride and dissolved organic carbon were also varied. Clear impacts of increased salt and dissolved organic carbon concentrations on nitrification activity and nitrifying bacterial populations were observed whereas clofibrinic acid (up to 100 µg/l) and ibuprofen (10 µg/l) showed no impact on the nitrification activity. The exposure to clofibrinic acid also showed no significant influence on the nitrifying bacterial population, while the addition of ibuprofen resulted in a slight shift of the population to a lower abundance of the β‐proteobacteria.