Geological gas-storage shapes deep life.

Area of Science:

• Microbial Ecology
• Geomicrobiology
• Environmental Microbiology

Background:

• Deep sedimentary aquifers are utilized for natural gas storage globally.
• Microbial communities, particularly sulfate-reducing and methanogenic microorganisms, are hypothesized to influence aquifer function during gas storage.

Purpose of the Study:

• To investigate the impact of natural gas storage on sulfate-reducing and methanogenic microbial groups in deep aquifers.
• To identify specific microbial taxa involved and their ecological roles.

Main Methods:

• High-throughput sequencing was employed to analyze microbial diversity.
• Geological factors and proximity to stored gas were correlated with microbial community composition.

Main Results:

• Microbial diversity showed significant variation with geological level.
• The ratio of sulfate-reducing Firmicutes to deltaproteobacteria was influenced by the distance to stored natural gas.
• A unique aquifer, previously storing hydrogen-rich town gas, exhibited dominance of methanogenic archaea over sulfate-reducers, with observed sulfate decrease potentially linked to stimulated sulfate-reducers.

Conclusions:

• Decades-old transient gas storage activities significantly impact the composition of deep subsurface microbial communities.
• The stability of these gas-impacted ecosystems suggests the long-term sustainability of in situ biotic methanation projects in geological reservoirs.