Janina Groninga

High-resolution mass spectrometry imaging of molecular biomarkers and isotopic signals for micrometer-scale mapping of microbial communities and metabolic activity in marine sediment

Despite the great relevance of marine subsurface sediment for our Earth's biogeochemical cycles,  our understanding of the complex, local biogeochemistry, the composition, and zonation of microbial communities within the ocean floor, and how they are shaped by changing geochemical and physical conditions is still limited. One powerful tool to study microbial life in subsurface sediment are molecular biomarkers. These structurally diverse molecules can provide us with a fingerprint of the microbes inhabiting the sediment.

Recently, MARUM scientists successfully adopted matrix-assisted-laser desorption mass spectrometry imaging (MALDI-MSI), a high-resolution technique allowing microscale visualization of biomarker distributions on a sample's surface from medical and biological sciences.

The exceptionally high resolution of MSI can shed new light onto the unaltered, millimeter-to-micrometer-scaled spatial distribution of multiple diagnostic biomarkers previously inaccessible.

In my Ph.D. project, I will focus on enabling micrometer-scaled visualization via MALDI-MSI for a wide range of known microbial metabolites and untargeted mass spectrometry imaging to shed light on the plethora of molecular biomarkers still hidden in the ocean floor sediment. Additionally, I will develop a new method for applying stable isotopes in MALDI-MSI.

In summary, my Ph.D. project explores the vast potential of highly resolved MSI on sediment samples and develops new methods for studying environmental influences on microbial communities in subsurface sediments via unaltered, microscale visualization of molecular biomarkers and isotopic signals.