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Abstract EANA2026-114


Poly-ploidy as mitigation strategy of Haloarchaea to radiation-induced DNA damages

Julian Leusner (1,2), Katharina Runzheimer (1), Kristina Beblo-Vranesevic (1), and Stefan Leuko (1)
(1) German Aerospace Center (DLR), Institute of Aerospace Medicine, Department Applied Aerospace Biology, Aerospace Microbiology Working group, Linder Hoehe, 51147 Cologne, Germany (2) Universita degli studi di Napoli Federico II, Dipartimento di Biologia, Via Cinthia 80126 Napoli, Italy


The habitability of extraterrestrial hypersaline environments remains a central question in astrobiology. Hypersaline brines on Earth are considered promising analog systems because evaporitic salt deposits and transient saline waters have been proposed for ancient and present-day Mars, too. Similar to the evaporation of ancient Martian oceans, the Zechstein Sea underwent extensive desiccation in the late Permian, leaving behind thick evaporite deposits that today harbor specialized halophilic microorganisms.

In this study, we investigate the adaptation of two halophilic archaeal isolates from Zechstein evaporites to near-saturated brine conditions and evaluate the potential relationship between polyploidy and radiation tolerance. Growth phase-dependent genome copy numbers will be quantified by qPCR in Halorubrum sp. AS12 and Haloarcula sp. NS06. Subsequently, both strains will be exposed to polychromatic UV-radiation (200-400 nm), and survival rates will be determined via plating assays. We hypothesize that elevated genome copy numbers enhance resistance to radiation-induced DNA damage by facilitating efficient homologous recombination and genome repair.

This work aims to clarify the role of regulated polyploidy as an adaptive strategy of haloarchaea under extreme environmental stress. Beyond its contribution to genome maintenance, polyploidy has also been proposed to function as an intracellular phosphate reservoir during nutrient limitation and desiccation. Understanding the relationship between genome copy number and diverse stress resistance may provide insights into microbial survival strategies in hypersaline extraterrestrial environments and contribute to assessments of planetary habitability.