Indian-led study suggests Martian perchlorate could aid bacteria-made bricks for habitats

A team led by researchers at the Indian Institute of Science investigated how a chlorine‑rich salt found on Mars, perchlorate, affects a soil‑binding bacterium used for biocementation. They spiked a Mars analog with perchlorate at laboratory concentrations and monitored a robust strain of Sporosarcina pasteurii for growth, extracellular material production and the mechanical quality of the resulting regolith bricks. As anticipated, the salt stressed the bacterial cells: growth slowed and cells aggregated, reflecting a physiological response to the toxin. Unexpectedly, the stressed bacteria secreted more extracellular matrix, and microscopy showed the matrix forming micro‑scale connections between cells and calcium carbonate crystals. Those microbridges correlated with increased crystal formation and a stronger consolidated material when a natural binder and a catalytic nickel source were present. The team frames this as a context‑dependent effect: perchlorate alone harms cells, but in a formulated mix the altered bacterial response can enhance particle bonding. The experiments used a commonly adopted Mars global simulant with carefully introduced perchlorate to avoid handling hazards; results therefore reflect controlled lab conditions rather than direct Martian field data. Next steps the authors identify include testing the biocementation workflow under carbon dioxide‑rich atmospheres and probing nutrient transport pathways through the extracellular matrix hypothesis. If the phenomenon holds under Martian pressures and temperatures, it could lower mass and cost penalties by reducing the amount of terrestrial construction material that must be launched. The work also raises biosafety and planetary protection questions: leveraging an in situ toxicant to benefit Earth microbes on Mars demands careful study of long‑term viability and contamination risk. Published in PLOS One, the paper connects microbiology, materials science and mission logistics in a practical line of inquiry for sustained Mars presence. Overall, the study reframes perchlorate from an exclusively problematic contaminant to a conditional enabler of engineered regolith consolidation, but it leaves open critical environmental and operational validations before deployment.