Isabelle Barth

For my doctoral thesis, I am investigating the effects of shear forces on the morphology and production of filamentous fungi. Filamentous fungi such as Penicillium have been established in the biotechnological industry for many years. A well-known example is the production of antibiotics or the production of citric acid by Aspergillus niger. Filamentous fungi produce a very wide range of interesting substances that are just waiting to be researched. In my work, I am focusing on the filamentous fungus Penicillium sp. IBWF 040-09, which is of interest because it produces a protease-inhibiting substance that could help in the fight against African sleeping sickness.

The growth of filamentous fungi can occur in two forms, either as pellets (small spheres) or as free mycelia (filaments). Depending on which growth form (morphology) occurs, production can be favored or reduced. My aim is to find the mechanical influencing factors and to optimize the reactor together with a doctoral student in mechanical engineering. It has already been shown that different flow conditions cause morphological changes in the fungus. The shear forces in the medium are to be determined by investigating the mixing time and CFD calculations. The interdisciplinary approach in our ParaMorphoPharm project should make it possible to obtain new bioreactor geometries in order to influence the fungal morphology during fermentation in the desired direction. In the project I am also working closely with two research groups at the Johannes Gutenberg University Mainz and a research group at the Technical University of Bingen, which are testing the extracts and the substances they contain against cancer cells or important targets against diseases or viruses.

A normal work day takes place almost completely in the lab. It consists of planning experiments, fermentation, i.e. growing the fungus and analyzing the experiment. After appr. one week of fermentation, it is possible to extract the products from the biomass formed. The analysis is carried out by separating the extract into different fractions using chromatography and performing an inhibition assay, i.e. a test that can detect the inhibition of a protease. This extraction process consists of many individual steps, which also have to be adapted and optimized. In addition to fermentation, I also carry out mixing time experiments in which a video of a color reaction is made and analyzed with different flows. This is used to assess the bioreactor setup and as a comparison for the CFD simulations of the flow. These results can then be used to plan new fermentations with other stirrers, internals or other bioreactor geometries. I am also considering new experiments with which I can quantify and qualify the growth form. To do this, I first plan the setup on paper. If individual parts are then required, I can design them using CAD and produce them using the 3D printer.