Effects of high CO2 concentrations on ecophysiologically different microorganisms.

Area of Science:

• Environmental microbiology
• Geological carbon sequestration

Background:

• Carbon capture and storage (CCS) involves injecting CO2 into deep geological formations.
• Potential leakage of CO2 into shallow aquifers necessitates understanding microbial responses.

Purpose of the Study:

• To assess the impact of elevated CO2 concentrations and pressure on diverse microorganisms.
• To provide data for risk assessment of CO2 leakage from geological storage sites.

Main Methods:

• Exposing aerobic (Pseudomonas putida, Bacillus subtilis) and anaerobic (Thauera aromatica, Desulfovibrio vulgaris) microorganisms to varying CO2 concentrations (atmospheric to 100%).
• Conducting experiments simulating deep CO2 storage conditions with pressures up to 5000 kPa.
• Monitoring microbial growth parameters (lag-phase, growth rate, cell yield) and viability.

Main Results:

• Elevated CO2 concentrations prolonged lag-phases and reduced growth rates and cell yields in a concentration-dependent manner.
• High CO2 levels up to 100% significantly inhibited microbial growth.
• Pressures ≥1000 kPa combined with high CO2 concentrations led to a significant decrease in living cells within 24 hours.

Conclusions:

• Microbial communities in shallow aquifers are vulnerable to CO2 leakage from deep storage.
• High CO2 concentrations and pressures pose a severe lethal threat to microorganisms.
• Findings are critical for evaluating the environmental impact and safety of CO2 storage projects.