Sven Basa successfully defended his PhD thesis

Today, Sven Basa successfully defended his PhD thesis, supported by his first and second referees, Prof. Bruno Moerschbacher and Prof. Andreas Hensel, from the Institute for Pharmaceutical Biology and Phytochemistry, as well as his third doctoral committee member, Prof. Jens Leker, from the Institute of Business Administration, the latter two from the Faculty of Chemistry and Pharmacy of our University. Sven continued work from previous doctoral candidates from our group who had found that when a chitosan polymer is degraded by different chitosanolytic enzymes, the resulting products can differ strongly in their bioactivities. When applied to healthy plants, these products acted either as elicitors of induced defence reactions, or as priming agents sensitizing plant cells for the perception of elicitors. The activities depend not only on the enzyme used for their production, but also on the plant species investigated. In a systematic approach involving a broad range of well characterised, recombinant chitinases, chitosanases, and chitin deacetylases, and sophisticated mass spectrometric structural analysis of their products, Sven unambiguously showed that the bioactivities of the chitosan oligomers not only depend on their degrees of polymerisation and acetylation, but also on their pattern of acetylation. Using mono-acetylated chitosan tetramers, he achieved the first proof ever that the position of the acetyl group critically determines the bioactivities of chitosans - a real breakthrough for chitosan structure-function analyses which he just published on the preprint server ChemRxiv.