Bacteria That Trap Carbon: Bacillus megaterium Offers Cleaner Pathway for CO₂ Mineralization

In the fight against climate change and unsustainable construction practices, scientists have discovered that the soil bacterium Bacillus megaterium can directly convert carbon dioxide (CO₂) into calcium carbonate (CaCO₃)—without relying on the ammonia-generating urease pathway commonly used in biocementation.

This cleaner microbial method of CO₂ mineralization not only offers a powerful carbon capture tool but also presents a sustainable alternative to cement in building applications.

“This is a major advancement in microbially induced carbonate precipitation (MICP) with real-world implications for eco-friendly construction and climate resilience,” said Dr. Dimitrios Terzis, co-author of the study.

Key Findings

94% of CaCO₃ was formed from CO₂, not from urea breakdown.
The carbonic anhydrase pathway was dominant in CO₂-rich environments.
This route avoids harmful ammonia production, which is typical in ureolytic MICP.
Crystals produced included calcite, vaterite, and aragonite—valuable polymorphs in construction.
The method is effective even in mildly acidic CO₂-enriched conditions.

Why This Matters

Current MICP technologies heavily rely on ureolytic bacteria like Sporosarcina pasteurii, which convert urea into carbonate but release ammonium, a toxic byproduct that demands costly wastewater treatment.

In contrast, B. megaterium:

Captures atmospheric CO₂ directly
Bypasses urea entirely under certain conditions
Offers a non-polluting biomineralization pathway

This makes it ideal for low-carbon construction, soil stabilization, and carbon-negative building materials.

How It Works

Under high CO₂ conditions, B. megaterium activates its carbonic anhydrase (CA) enzyme, which catalyzes the conversion of gaseous CO₂ into bicarbonate. This bicarbonate then reacts with calcium ions to precipitate CaCO₃.

By contrast, under normal conditions, the urease pathway is activated, breaking down urea into ammonium and carbonate. But in closed systems with high CO₂, the CA pathway is preferred.

“This dual enzymatic ability makes B. megaterium a powerful and flexible bioengineer,” the authors wrote.

Applications

Eco-friendly biocement for green construction
Carbon sequestration in closed-loop systems
Bio-restoration of stone monuments
Soil stabilization and environmental remediation

Bacillus megaterium_ New Era in Carbon Sequestration

Reference

Cappa, M., Perego, C., Terzis, D., & Principi, P. (2025). Bacillus megaterium favours CO₂ mineralization into CaCO₃ over the ureolytic pathway. Scientific Reports, 15(1), 21861. https://doi.org/10.1038/s41598-025-07323-9