Biogeochemical survey of highly polar metabolites using mass spectrometry and metabolomics.

High polar metabolites can be found in phytoplankton and play crucial ecological and biochemical roles. These compounds are part of microbial communication, adaption to oxidative and osmotic stress but also serve as nutrient source of sulphur or carbon. The most abundant representatives of these chemicals are d imethylsu lfoniopropionate (DMSP) and dimethylsu lfoxoniu m propionate (DMSOP). Both are important due to their influence on global climate, acting as natural precursors of methane and d imethylsu lfide. This project aims to evaluate workflows for the detection of high-polar metabolites using UPLC/MS. The methods will be applied to both, laboratory cultures and environmental samples. A focus of this thesas are environmental samples obtained by the metabolomics protocol of the TREC project (transversing European coastline). This proiect is led by the European Molecular Biology Laboratory (EMBL) and took place from 2023 to 2024. During the project time samples of the coastal ecosystems were taken at 140 European sites with a high environmental diversity. Since samples were taken in the deep, coastal and shallow water a broad spectrum of data supposed to allow the study of microbial interaction at different sea levels. ln this thesis both untargeted and targeted metabolomics approaches will be employed on the obtained and received filter samples. Untargeted analyses aim to discover novel metabolites, while targeted metabolomics screening of known compounds. This will help improve the understanding of microbial interactions in complex communities. By combining these approaches, this work seeks to contribute to a deeper understanding of microbial ecology in marine environments, with relevance to symbiosis, predator-prey interactions, and chemotaxis.

PhD start: 08/01/2025