Impact of paleoclimate on the distribution of microbial communities in the subsurface sediment of the Dead Sea

Article Article scientifique Article Impact of paleoclimate on the distribution of microbial communities in the subsurface sediment of the Dead Sea eng 2015 author Thomas Camille 739432 author Ionescu Denisse 690730 author Ariztegui Daniel 0000-0001-7775-5127 133805 DSDDP scientific team 546-561 10.1111/gbi.12151 1472-4669 A long sedimentary core has been recently retrieved from the Dead Sea Basin (DSB) within the framework of the ICDP-sponsored Dead Sea Deep Drilling Project. Contrasting climatic intervals were evident by distinctive lithological facies such as laminated aragonitic muds and evaporites. A geomicrobiological investigation was conducted in representative sediments of this core. To identify the microbial assemblages present in the sediments and their evolution with changing depositional environments through time, the diversity of the 16S rRNA gene was analyzed in gypsum, aragonitic laminae, and halite samples. The subsurface microbial community was largely dominated by the Euryarchaeota phylum (Archaea). Within the latter, Halobacteriaceae members were ubiquitous, probably favored by their ‘high salt-in' osmotic adaptation which also makes them one of the rare inhabitants of the modern Dead Sea. Bacterial community members were scarce, emphasizing that the ‘low salt-in' strategy is less suitable in this environment. Substantial differences in assemblages are observed between aragonitic sediments and gypsum–halite ones, independently of the depth and salinity. The aragonite sample, deposited during humid periods when the lake was stratified, consists mostly of the archaeal MSBL1 and bacterial KB1 Candidate Divisions. This consortium probably relies on compatible solutes supplied from the lake by halotolerant species present in these more favorable periods. In contrast, members of the Halobacteriaceae were the sole habitants of the gypsum–halite sediments which result from a holomictic lake. Although the biomass is low, these variations in the observed subsurface microbial populations appear to be controlled by biological conditions in the water column at the time of sedimentation, and subsequently by the presence or absence of stratification and dilution in the lake. As the latter are controlled by climatic changes, our data suggest a relationship between local lacustrine subsurface microbial assemblages and large-scale climatic variations over the Dead Sea Basin. Dewey 550 Swiss National Science Foundation Dead Sea Deep Drilling Project: The Swiss contribution (DSDDP-CH) - Phase II 149221 CH Project funding 42 Département des sciences de la Terre 154 false 664 Limnology and Geomicrobiology Geobiology 13 6 cfd35b33-7ebe-4499-913e-56e240b30603 Article (Published version) Restricted Thomas_et_al-2015-Geobiology.pdf 3088544 application/pdf restrictedAccess Faculté des sciences / Section des sciences de la Terre et de l'Environnement / Département des sciences de la Terre

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Impact of paleoclimate on the distribution of microbial communities in the subsurface sediment of the Dead Sea	Geobiology			2015	539	1

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Ionescu, Denisse