Lay summary
About 25 % of the global population is depending on drinking water from karstic groundwater resources. Consequently, alpine karst research has to provide the basic scientific understanding which enables to take all necessary steps for long term maintaining of the ecological integrity of the respective alpine catchment areas.

The proposed study will be the first comprehensive attempt to establish an ultra-deep sequencing framework of autochthonous karstic aquifer communities in the Central European Region. Arising from earlier results, the hypothesis of a distinct assemblage of autochthonous microbial endokarst communities (AMEC), reflecting hydrogeology and lithological composition of an aquifer, has the potential to blaze the way for a plethora of questions, ranging from evolutionary aspects and survival strategies to speculations about endemic subsurface communities. The rapid development in high throughput parallel sequencing approaches and novel tools like total community divergence measures, now allow to verify and expand the AMEC-concept by comparing autochthonous aquifer communities on a regional scale. However, microbial communities present in alpine karst aquifers sometimes have to withstand tremendous changes of environmental parameters such as water levels and nutrient availability. Microbes overcome these challenges often by altering their protein expression profiles but not by immediate genomic rearrangements. Consequently, the mere study of individual genes and their regulation is not sufficient to fully understand microbial adaptation strategies and post-genomic analyses such as proteomics is urgently needed to investigate structure and physiology of complex microbial consortia at a molecular level.

This study aims at building the base for a robust eco-phylogenetic framework in the karstic subsurface at an unprecedented resolution. It will furthermore use in situ and lab experiments to shed light on interactions between attached autochthonous communities and the prevailing hydrogeological conditions. A multi-parametric statistical approach including a wealth of lithological, hydrological, chemical and microbiological background data will put the results in a broader context and establish a basis for pointed research questions in karstic groundwater environments that will reach far beyond the Central European Region. Thereby, this project will not only be groundbreaking for basic research in the relatively young field of environmental microbiology, but it will also be important for sustainable water resource management and provide fundamental data for eco-toxicology and risk assessment in groundwater aquifers.