SPP1158 Antarctica

Microbial-induced pedogenesis: Microaggregates as nucleus for initial soil formation

01/02/2025 to 31/01/2029

In Antarctica, soil development begins immediately after the retreat of the ice and snow masses. Our previous research in Antarctica has shown that the terrestrial microbiome reacts quickly to environmental changes and that soil structure and soil aggregates form with distinct physical boundaries. We therefore assume that the processes of soil formation are initially spatially segmented and that microhabitats develop inside and on the surfaces of aggregates. In order to better understand the interactions between microorganisms, initial soil formation and microhabitats, we therefore want to analyze aggregate interiors and exteriors separately. With this approach, we go beyond the established analysis of physical, chemical and microbiological properties of whole aggregates or aggregate size fractions, whose spatial resolution is not high enough to gain detailed insights into initial pedogenic processes including microbially induced soil formation.

This approach requires new methods and strategies for combining existing measurement techniques. With the fluorescence labelling of microorganisms on aggregate surfaces and the separation of labelled and unlabeled cells inside the aggregate using the flow cytometer technique, the inner and outer spheres of aggregates are to be examined separately. In addition, the measurement data of the soil architecture and the element contents, which have different spatial resolutions depending on the measurement technique, are synchronized and combined with the data of the microbiological analyses. In this way, the different measurement methods (micromorphology, fluorescence microscopy, X-ray computed tomography (µCT), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and secondary ion mass spectrometry in the nanometer range (NanoSIMS)) can be evaluated in a spatially differentiated manner on the micro- and nanometer scale. Finally, we train machine learning algorithms with all analysis data and model the initial soil formation including the microbiome for the first time.

With our research, we want to expand our knowledge of how and to what extent microorganisms initiate and promote soil formation in cold deserts such as the Antarctic, and to better understand the processes of polar soil formation and habitat development for microorganisms. The expected results can make an important contribution to the understanding of biogeochemical cycles (research topic C "Response to environmental change") and the importance of key species (research topic D "Improved understanding of polar processes and mechanisms") for the development of terrestrial ecosystems in Antarctica under climate change.