Microbial diversity and biogeochemical interactions in the seismically active and CO₂- rich Eger Rift ecosystem

Area of Science:

• Geomicrobiology
• Deep Biosphere Research
• Environmental Science

Background:

• The Eger Rift exhibits seismic activity and high carbon dioxide (CO2) levels, creating a unique deep biosphere.
• Geogenic hydrogen (H2) pulses during earthquakes may fuel microbial processes, but their role is poorly understood.
• Understanding microbial life in geologically active subsurface environments is crucial.

Purpose of the Study:

• To investigate the impact of geological activity on microbial communities in the Eger Rift subsurface.
• To analyze the geological, geochemical, and microbiological characteristics of a 238m deep drill core.
• To determine the diversity and distribution of bacterial and archaeal populations.

Main Methods:

• Drilling and core sample collection from six lithostratigraphic zones.
• Geological, geochemical, and microbiological analyses of rock and sediment samples.
• Assessment of bacterial and archaeal community diversity and distribution.

Main Results:

• A low-biomass, yet diverse archaeal community was identified, including methanogenic archaea.
• Elevated ion concentrations (sodium, sulfate) were found in specific sediment and rock layers.
• Microbial communities comprised common soil/water bacteria, freshwater cyanobacteria, and anaerobic, autotrophic, acidophilic sulfur-cycling taxa.
• Evidence for methanogenic, halophilic, and ammonia-oxidizing archaea was detected.

Conclusions:

• The Eger Rift subsurface supports diverse microbial life, utilizing geologically derived CO2 and H2.
• Microbial communities are influenced by geological activity, geochemistry, and groundwater movement.
• The findings highlight the potential for microbial life in volcanically and tectonically active deep subsurface environments.