Life on the edge: active microbial communities in the Kryos MgCl2-brine basin at very low water activity.

Steinle, Lea, Knittel, Katrin, Felber, Nicole, Casalino, Claudia, de Lange, Gert, Tessarolo, Chiara, Stadnitskaia, Alina, Sinninghe Damsté, Jaap S., Zopfi, Jakob, Lehmann, Moritz F., Treude, Tina and Niemann, Helge (2018) Life on the edge: active microbial communities in the Kryos MgCl2-brine basin at very low water activity. The ISME Journal, 12 (6). pp. 1414-1426. DOI 10.1038/s41396-018-0107-z.

[img] Text
Steinle.pdf - Reprinted Version
Restricted to Registered users only

Download (1311Kb) | Contact

Supplementary data:

Abstract

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.

Document Type: Article
Keywords: CARBON ISOTOPIC FRACTIONATION; ANAEROBIC METHANE OXIDATION; SULFATE-REDUCING BACTERIA; HYPERSALINE ANOXIC BASINS; PHOSPHOLIPID FATTY-ACID; RED-SEA; MEDITERRANEAN SEA; BLACK-SEA; MASS-SPECTROMETRY; LIPID BIOMARKER; RV Meteor; M83/3
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
NIOZ
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1038/s41396-018-0107-z
ISSN: 1751-7362
Projects: PERGAMON
Expeditions/Models/Experiments:
Date Deposited: 31 May 2018 06:51
Last Modified: 01 Feb 2019 15:06
URI: http://oceanrep.geomar.de/id/eprint/43205

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...