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Abstract EANA2025-58


Preservation of Microbial Signatures in Continental Sabkhas: Implications for Mars Analog Studies

Barbara Cavalazzi (1), Alice Tarozzi (1), Fulvio Franchi (2), Yelena Caddeo (3), Francesca Mancini (3), Alessia Cassaro (4), Claudia Pacelli (4), Lesedi Lebogang (5), Trash H. Kashay (5), Youcef Sellam (6), Sakina Kallef (7), Monica Pondrelli (3)
(1) Università di Bologna, Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Bologna, Italy (2) Università degli studi di Bari – Aldo Moro, Dipartimento di Scienze della Terra e Geoambientali, Bari, Italy (3) International Research School of Planetary Sciences, Università d’Annunzio, Dipartimento di Ingegneria e Geologia, Pescara, Italy (4) Italian Space Agency, Science and Innovation Directorate, Rome, Italy (5) Botswana International University of Science and Technology, Department of Mineral Resources, School of Earth Sciences and Engineering, Palapye, Botswana (6) University of Bern, Physics Institute, Space Reseach and Planetary Sciences, Bern, Switzerland (7) Université Kasdi MERBAH, Département des Sciences Biologiques, Ouargla, Algérie


Continental sabkhas are dynamic evaporitic environments marked by high salinity, episodic water influx, and extreme diurnal temperature fluctuations. These conditions not only sustain microbial life adapted to environmental stress, but also promote rapid mineral precipitation capable of encapsulating and preserving biosignatures.

In this study, we investigate the biogeochemical pathways involved in biosignature preservation across two contrasting sabkha systems: Makgadikgadi (Botswana) and Tanezrouft (Algeria). Our multidisciplinary approach—combining field observations, petrographic analyses, and microbiological profiling—examines how biomineralisation, desiccation–rehydration cycles, and evaporite dynamics shape microbial preservation potential.

We focus in particular on the in-situ precipitation of halite and gypsum crusts and their ability to entomb extracellular polymeric substances (EPS), microbial sheaths, and organic residues. Despite differing climatic and geographic contexts, both sites exhibit convergent processes that enhance biosignature retention.

These findings refine current models of microbial fossilisation in terrestrial saline environments and offer key insights for astrobiology. The sabkhas examined here represent valuable analogues for Martian evaporitic terrains, where similar depositional settings have been identified by orbital and rover missions.

By highlighting the interplay between microbial ecology and sedimentary mineral dynamics, this research contributes to the development of more effective biosignature detection strategies for upcoming planetary exploration missions.

 

Acknowledgments: This research was supported by the National Recovery and Resilience Plan (NRRP), Mission 4, Component 2, Investment 1.1, Call No. 104 (2.2.2022), funded by the European Union – NextGenerationEU (Grant No. 2022LFXTKY) issued by the Italian Ministry of University and Research – MUR.