Successional Trajectories of Deep Subsurface Microbiomes in Response To Experimental Dihydrogen Injection.

Area of Science:

• Environmental microbiology
• Geomicrobiology
• Biogeochemical cycling

Background:

• Converting gas storage to dihydrogen (H2) storage necessitates understanding microbial impacts.
• Prokaryotic consumption and community shifts affect H2 storage quality and efficiency.
• Deep aquifer conditions (pressure, temperature) influence microbial responses to H2.

Purpose of the Study:

• To identify consistent community-level microbial responses to dihydrogen injection in simulated deep aquifers.
• To assess the ecological dynamics and potential predictability of microbial communities during H2 storage transitions.

Main Methods:

• Analysis of five dihydrogen pulse experiments in pressurized bioreactors simulating deep aquifer conditions.
• Monitoring microbial community composition and geochemical parameters over time.
• Utilizing amplicon sequence variants (ASVs) to track microbial populations.

Main Results:

• Consistent decline in fermentative ASVs due to environmental filtering.
• Initial dominance of hydrogenotrophic sulfate reducers, leading to sulfate depletion in some cases.
• Emergence of methanogenic archaea and potential deterministic succession patterns (e.g., Thermodesulfovibrio, Methanothermobacter).

Conclusions:

• Microbial dynamics are critical for dihydrogen storage in deep aquifers.
• Predictable ecological succession may occur under specific geochemical conditions, despite initial variability.
• Potential selection pressures and dispersal limitations influence community structure.