Flow Cytometry Assessment of Microalgae Physiological Alterations under CO₂ Injection

Area of Science:

• Environmental Science
• Biotechnology
• Ecotoxicology

Background:

• Carbon capture and storage (CCS) is crucial for CO2 mitigation but carries risks of leakage.
• CO2 leakage can lead to significant environmental impacts, such as drastic pH drops.
• Effective monitoring tools are needed to assess the ecological consequences of potential CO2 leaks.

Purpose of the Study:

• To evaluate specific biological endpoints as potential biomarkers for CO2 exposure.
• To determine if flow cytometry can be integrated into risk assessment and monitoring programs for CCS.
• To assess the sensitivity, timeliness, cost-effectiveness, and interpretability of proposed biomarkers.

Main Methods:

• The study utilized Scenedesmus (Acutodesmus) obliquus as a model organism.
• Flow cytometry was employed to measure growth rate (GR), esterase activity (EA), membrane potential (MP), and DNA content.
• Algae were exposed to high levels of injected CO2 to simulate leakage scenarios.

Main Results:

• High CO2 levels significantly affected esterase activity, membrane potential, and growth rates in the algae.
• DNA content did not exhibit a clear or consistent response to elevated CO2 conditions.
• The measured endpoints demonstrated sensitivity, timeliness, and ease of measurement, fulfilling key biomarker criteria.

Conclusions:

• Growth rate, esterase activity, and membrane potential, analyzed via flow cytometry, are proposed as reliable biomarkers for CCS monitoring.
• These endpoints are suitable for inclusion in risk assessment and environmental monitoring programs related to CCS.
• The study highlights the utility of flow cytometry in detecting CO2-induced stress in aquatic ecosystems.