(German title: Untersuchung der Adhäsion terrestrischer Cyanobakterien auf unterschiedlichen Oberflächen)

The cultivation of phototrophic microorganisms as a biofilm can make biotechnological processes simpler and more efficient. The product purification of secreted substances is facilitated by immobilized cells and higher productivities can be achieved in continuous processes, as the growth rate can be decoupled from the dilution rate. Although the cultivation of terrestrial cyanobacteria in submerged systems is possible, changes in the cell morphology and EPS of Nostoc flagelliforme, for example, have been described, resulting in low yields and cell viability. This is where the project would like to start and investigate the relationship between the ratio of biomass to EPS and the adhesion strength of the biofilm over the cultivation period on different substrates. On the one hand, the adhesion behavior provides information about the point in time after inoculation of the reactor at which the biofilm cannot be washed off the surfaces by the addition of medium in the form of aerosol. To determine the adhesion of single-cell organisms, a force-distance curve is recorded using an atomic force microscope. For this method, either a single cell must be fixed to the cantilever or several cells must be immobilized on the cantilever. As cyanobacteria grow in cell clusters that cannot be separated, various methods for immobilizing a biofilm on the cantilever have already been tested, but have not yet been successful. This shows that determining the forces acting between the cyanobacterial cells and the surface is not trivial. A flow chamber is now to be constructed in which different surfaces can be variably inserted. The biofilm is to be cultivated on the surfaces in an aerosol reactor and then flowed over with different flow velocities in the flow chamber. The forces acting on the biofilm can be calculated using the flow velocity.