Potential Cell Preservation in Mars-relevant Clay Minerals

This study investigates the potential of Fe-nontronite, a clay mineral found on Mars, to preserve biological cells and retain biosignatures such as trace metals. The research explores the preservation potential of nontronite by reacting it with cells under the following conditions: 1) reacting cells with nontronite precursors at low temperature and 2) reacting cells with the already synthesized nontronite made at high temperature. Microbial species Shewanella oneidensis and Geobacter metallireducens, known for their relevance to iron-rich environments, were introduced in intact and lysed forms to assess their interactions with each condition of nontronite. Preliminary results from scanning electron microscopy (SEM) showed that the synthesized nontronite samples exhibit crystallinity typical of nontronite clay minerals. In existing literature, enhanced crystallinity in clay minerals is associated with better preservation of trace metals as the structured mineral environment can protect cells from degradation. We hope to observe similar protective qualities in our nontronite samples. As the research continues, we are working on imaging the remaining samples and completing the setup of additional experimental conditions. Further mineralogical analysis and structural evaluation using techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM) and inductively coupled plasma mass spectrometry (ICP-MS) will be conducted. This research aims to contribute to astrobiology by exploring how nontronite can preserve biosignatures, helping to identify materials and conditions on Mars that may protect evidence of past life. This study hopes to provide valuable insights into the role of Martian analog minerals in preserving biological materials.