Life at the Edge: A Study on the Prokaryotic Communities Associated with Assale Lake and its Salt Flat (Danakil Depression, Ethiopia).

Supervisor: Ricardo Amils Pibernat (CBMSO- Univ. Autónoma Madrid).
Located on the triple-junction between the Somalian, Nubian and Arabian plates, the hypersaline system comprising the Assale lake and its surrounding salt flat, represents a unique environment for which ecological studies have never been carried before. Despite of its immense potential for harbouring halophilic and/or halotolerant microorganisms, previous attempts to isolate its strains were rather frustrating and a second attempt of culturing was carried during this work, along with a deep analysis of the physico-chemical parameters and community composition present in this environment. The outcomes of this study reveal a system that gathers features observed in other superficial hypersaline environments with that presented by the deep-sea brines, what is especially true concerning the lake itself. As for deep-brines, the Assale lake displays a reduced prokaryotic abundance, along with an unusual predominance of archaea over bacteria, what may result from a high concentration of chaotropic ions on these environments. Moreover, most of the archaeal isolates obtained from these habitats were shown to consist of new species or even new genera of halobacteria, a fact probably coming as a result of the isolation of the system from other habitats for millions of years. The data obtained reinforces the singularity of the Assale’s salt deposits and further work carried on this environment will contribute greatly for a better understanding of the different processes taking place in submarine brine lakes and other hypersaline water bodies present around the world.