Life on the edge: active microbial communities in the Kryos MgCl 2-brine basin at very low water activity

Steinle, Lea and Knittel, Katrin and Felber, Nicole and Casalino, Claudia and de Lange, Gert and Tessarolo, Chiara and Stadnitskaia, Alina and Sinninghe Damsté, Jaap S. and Zopfi, Jakob and Lehmann, Moritz F. and Treude, Tina and Niemann, Helge. (2018) Life on the edge: active microbial communities in the Kryos MgCl 2-brine basin at very low water activity. ISME Journal, 12. pp. 1414-1426.

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Official URL: https://edoc.unibas.ch/73084/

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The Kryos Basin is a deep-sea hypersaline anoxic basin (DHAB) located in the Eastern Mediterranean Sea (34.98°N 22.04°E). It is filled with brine of re-dissolved Messinian evaporites and is nearly saturated with MgCl2-equivalents, which makes this habitat extremely challenging for life. The strong density difference between the anoxic brine and the overlying oxic Mediterranean seawater impedes mixing, giving rise to a narrow chemocline. Here, we investigate the microbial community structure and activities across the seawater–brine interface using a combined biogeochemical, next-generation sequencing, and lipid biomarker approach. Within the interface, we detected fatty acids that were distinctly 13C-enriched when compared to other fatty acids. These likely originated from sulfide-oxidizing bacteria that fix carbon via the reverse tricarboxylic acid cycle. In the lower part of the interface, we also measured elevated rates of methane oxidation, probably mediated by aerobic methanotrophs under micro-oxic conditions. Sulfate reduction rates increased across the interface and were highest within the brine, providing first evidence that sulfate reducers (likely Desulfovermiculus and Desulfobacula) thrive in the Kryos Basin at a water activity of only ~0.4 Aw. Our results demonstrate that a highly specialized microbial community in the Kryos Basin has adapted to the poly-extreme conditions of a DHAB with nearly saturated MgCl2 brine, extending the known environmental range where microbial life can persist.
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Geowissenschaften
05 Faculty of Science > Departement Umweltwissenschaften > Geowissenschaften > Geochemie Stoffkreisläufe (Lehmann)
UniBasel Contributors:Zopfi, Jakob
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Nature Publishing Group
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:14 Sep 2020 07:23
Deposited On:14 Sep 2020 07:23

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