NOVAC – Novel viruses of terrestrial subsurface archaea impacting global carbon cycling

• Applicant: Professor Dr. Alexander Probst
• Subject Area: Microbial Ecology and Applied Microbiology
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 429483359

The (deep) continental subsurface is home to a great abundance and diversity of archaea and bacteria, yet little is known about the viruses that infect these organisms. Of particular interest are dominant primary producers as they jump-start the food chain in these oligotrophic ecosystems and could in theory be an important target for viruses. In this proposal we hypothesize that Altiarchaeota, an uncultivated group of autotrophic subsurface archaea that occur in hot spots across the globe, are frequent targets of novel viruses that consequently impact carbon cycling. In preliminary results, we were able to bioinformatically identify putative viruses infecting Altiarchaeota and showed the actual infection of one of these viruses in the ecosystem using direct-geneFISH. Building on this prerequisite knowledge, we will first identify mobile genetic elements that infect Altiarchaeota, in public datasets collected from subsurface locations across the globe. These elements will include viruses, one of which will be investigated in detail regarding its microdiversity in our main study site in Germany. In our second goal, we will visualize and calculate the infection rates of the selected virus in the ecosystem using a combination of direct-geneFISH, superresolution microscopy and Raman microscopy. In the third goal, we plan to identify the structure of the predicted virus using three independent microscopy approaches. These approaches include direct-geneFISH-mediated atomic force microsopy and transmission electron microscopy as well as immunogold labeling of viral proteins with antibodies generated from predicted and heterologously expressed proteins. These approaches will ultimately result in a comprehensive dataset of one uncultivated virus-host relationship in order to unravel the different infection stages of a virus in the actual ecosystem. The results of this proposal will shed new light on the diversity and function of deep subsurface viruses that infect autotropic archaea and thus alter carbon cycling in these environments.

• DFG Programme: Research Grants