Abstract EANA2026-121

Identifying biosignatures of early life requires understanding how microbial activity becomes encoded in the mineral record. Extracellular polymeric substances (EPS) produced by microorganisms play a fundamental role at the interface between life and minerals. These organic matrices influence sediment stabilization, mineral nucleation, and the formation of biosignatures that can persist in the geological record long after the degradation of the original biomass. EPS are therefore increasingly recognized as key agents in the formation of both microbially induced sedimentary structures (MISS) and authigenic minerals, making them highly relevant to the search for evidence of past life on Earth and other planetary bodies.

Particularly valuable in this context are modern evaporitic environments, where EPS-rich microbial mats thrive under conditions—including high salinity, aridity, and fluctuating water availability—that resemble those inferred for portions of early Earth and early Mars. Research conducted in the coastal sabkhas of Qatar has provided new insights into the interactions between microbial communities, EPS, sediments, and mineral formation in such extreme settings, suggesting that microbial processes may strongly influence both the preservation of morphological biosignatures and the precipitation of carbonate and sulfate minerals over geological timescales.

These observations highlight the central role of EPS in controlling mineral nucleation, a process that may be sensitive to gravitational conditions. To explore this possibility, AstroBioMineralization, a project proposed for the International Space Station, aims to investigate whether EPS-mediated biomineralization can occur under microgravity conditions. By comparing minerals formed in space with their terrestrial counterparts, this study will help evaluate the robustness of microbial–mineral interactions beyond Earth and contribute to our understanding of biosignature formation in planetary environments.