Sonja Raetz successfully defended her Master thesis: “Bioactivity of enzymatically produced chitosans with blockwise acetylation patterns”.

Today, Sonja Raetz successfully defended her Master thesis on the use of enzymatically produced chitosans for plant protection, supported by Prof. Bruno Moerschbacher, and by Prof. Jochen Schmid from the Institute for Molecular Microbiology and Biotechnology. In contrast to our previous work using chitinases and chitosanases on chemically produced chitosans with random acetylation patterns, Sonja targeted our new biotechnologically produced chitosans with blockwise distribution of acetyl groups, combined with enzymes which due to their unique cleavage specificities were expected to yield very specific and very unusual oligomeric products when hydrolysing the chitosan polymers. Unfortunately, the chitosanase she selected based on a recent publication turned out to be just an ordinary chitosanase with no interesting features. On the other hand, the second enzyme, our chitinosanase from the fungus Alternaria alternata, yielded the expected oligomers with block-distribution of acetyl groups. Sonja was supervised by Dr.Carolin Richter in the functional analysis of the chitosan polymers and oligomers regarding their antimicrobial and phytostimulatory activities, supported by Dr. Stefan Cord-Landwehr who helped with their structural analysis. She also travelled to the Max Planck Institute for Plant Breeding Research in Cologne to learn handling powdery mildew as a pathogen of Arabidopsis, a plant-pathogen system she then successfully established in our lab. After her defense, Sonja fortunately keeps working with us for a while, to finalise testing her new chitosansin her new bioassay.