Engineering living building materials for enhanced bacterial viability and mechanical properties

Area of Science:

• Materials Science
• Biotechnology
• Civil Engineering

Background:

• Living building materials (LBMs) integrate microorganisms to create novel construction materials.
• A recent advancement includes hydrogel-based LBMs utilizing microbially induced calcium carbonate precipitation (MICP).

Purpose of the Study:

• To evaluate key LBM design factors: gel/sand ratio, trehalose inclusion, and MICP pathways.
• To understand how these factors influence mechanical properties and failure modes.

Main Methods:

• Investigated LBMs with varying gel/sand ratios (0.13 and 0.30) to observe failure modes.
• Assessed the effect of trehalose on bacterial viability under low humidity.
• Compared MICP efficiency using different bacterial strains (heterotrophic ureolytic Escherichia coli, ureolytic Synechococcus, and CO2-concentrating Synechococcus).

Main Results:

• Distinct failure modes were observed in non-saturated (gel/sand = 0.13) and gel-saturated (gel/sand = 0.30) LBMs.
• Trehalose inclusion preserved bacterial viability without compromising mechanical strength.
• LBMs with Escherichia coli showed the greatest mechanical enhancement compared to controls and other microbial pathways.

Conclusions:

• LBM properties can be tailored by controlling microstructure and selecting appropriate MICP pathways.
• The choice of microorganism and its metabolic pathway critically impacts material performance.
• This research provides insights for designing more robust and functional living building materials.