Biofilm analysis

Laser scanning microscopy (LSM) is a powerful technique for examination of 3-dimensional microbial communities. In combination with various fluorescence staining techniques, 1-photon or 2-photon excitation can be used to record signals in multiple channels. By means of LSM the distribution of cellular and polymeric constituents as well as the microhabitat can be examined in biofilms and bioaggregates.

(cooperation with J. R. Lawrence, Environment Canada, Saskatoon)

Biofilm matrix

Extracellular polymeric substances (EPS) of interfacial microbial communities have a key role in terms of biofilm functionality. Fluorescence lectin-binding analysis (FLBA) represents a useful approach for staining of lectin-specific EPS glycoconjugates. FLBA allows in situ detection of glycoconjugates in relation to the producing microorganisms.

(cooperation with J. R. Lawrence, Environment Canada, Saskatoon)

Antifouling compounds

Biofouling on ship hulls continues to be a scientific and practical challenge. After banning tributyltin as a toxic antifouling compound there is still no satisfactory replacement. Therefore several research groups explore a range of different strategies in order to control biofouling.

(cooperation with Fraunhofer Institute and several SME’s)

Biofilms and mineral formation

Organic films and biofilms are ubiquitous on every aquatic interface. They represent an active biological structure which is involved in the cycling of elements. Cellular constituents may produce gradients whereas polymeric constituents create microhabitats, both are important for mineral formation.

(DFG research group 571)

PCB biofilms

Polychlorinated biphenyls (PCB’s) are critical environmental contaminants as they are recalcitrant and may find their way into the food chain. The microbial degradation of PCB droplets in a biofilm microcosm revealed a characteristic pattern which was supported by chemical analysis, molecular biology studies and laser microscopy.

(cooperation with W.-R. Abraham, HZI Braunschweig)

Fungal highway

Fungal filaments in soil are able to bridge saturated and unsaturated locations. This feature may be of advantage to other microorganisms. In fact it was shown that bacteria may take the “fungal highway” in order to reach their substrate. Key element for this option is the fungal cell surface which is covered by an aqueous film along which the bacteria can migrate.

(cooperation with H. Harms, L. Y. Wick, UFZ Leipzig)

Viruses in river snow

Viruses from the aquatic environment are usually detected after filtration and staining on membranes. Nevertheless viruses are also attached to aquatic aggregates, an aspect which was largely neglected. Therefore the possibility to examine viruses on hydrated river aggregates by means of laser microscopy was elaborated.

(cooperation with P. Peduzzi, University of Vienna)

Aquifer microbiology

Groundwater aquifers of industrial areas are often contaminated with aromatic hydrocarbons. Frequently this habitat becomes anoxic. Consequently the anaerobic degradation of benzene was investigated in laboratory microcosms. By using different approaches the microbial community involved in degradation of benzene was studied.

(cooperation with M. Kästner, H. Richnow, C. Vogt, UFZ Leipzig)

Biofilm strength

Knowing the mechanical strength of biofilms is of utmost significance for wanted and unwanted biofilms. Fluid dynamic gauging (FDG) was used to measure the cohesive strength of biofilms developed in rotating disc reactors. In parallel biofilms were visualised before and after FDG showing a stable base biofilms with a high amount of EPS.

(cooperation with H. Horn, TU Munich and D. C. Hempel, TU Braunschweig)

Biofilm detachment

Microbial biofilm history includes biofilm development and biofilm detachment. Especially in long-term experiment detachment becomes a major aspect in terms of structure and function of the microbial communities. The critical parameters are: substrate availability, hydrodynamic conditions and community composition.

(cooperation with H. Horn, TU Munich)


Biofouling in technical systems represents a big challenge. One out of many examples is represented by fouling of paper machines. A Deinococcus geothermalis strain isolated from paper machine water showed multiple strategies for attachment to surfaces. Strikingly was the production of several types of glycoconjugates which seem to be involved in attachment, colony formation and movement across surfaces.

(cooperation with M. S. Salkinoya-Salonen, University of Helsinki)


Beggiatoa species are known to exist at the oxic-anoxic interface in aquatic habitats. In addition, Beggiatoa are involved in the turnover of nitrogen and sulphur compounds. In order to understand the behaviour and metabolism of Beggiatoa microsensor, stable isotope and advanced microscopy techniques were employed.

(cooperation with D. de Beer, MPI for Marine Microbiology, Bremen)

Phototrophic biofilms

Aquatic biofilms exposed to light are dominated by phototrophic micro-organisms. Cyanobacteria and unicellular algae generate energy, reduce carbon dioxide and provide organic substrates as well as oxygen which drive processes in the overall biofilm community. Practical implications include biofouling but also bioremediation. Production of extracellular polymeric substances (EPS) may enhance the stabilisation of sediments and soils.

(EU project PHOBIA – The Netherlands, Denmark, Italy, Portugal, Germany)

Rock biofilms

Endolithic phototrophic biofilm communities are pioneering organisms in extreme habitats. They form a distinct layer just a few mm below the rock surface. In this study dolomite rock from the Swiss Alps was examined by means of 1-photon and 2-photon laser scanning microscopy. The data showed different types of phototrophs partly embedded in a dense layer of EPS.

(cooperation with R. Bachofen, University of Zuerich, Switzerland)