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Main research field: At present, I am actively working on the microbiology of microbial mats and stromatolites. One original aspect of my current research is the study of the influence of microbial mats on the preservation and early stages of fossilization of macroorganisms.
STSM title: Identification of extremophilic microbial species isolated from Dallol samples (Ethiopia) using molecular methods and analysis of chemical data
Host institution: Ecologie Systematique Evolution Laboratory. UMR CNRS UPSud-AgroParisTech 8079, Orsay CEDEX. (FR).
Host scientist: David Moreira
Period: 2016-07-06 to 2016-08-03
In January 2016, I took part in a 12-days multidisciplinary expedition to the Dallol hydrothermal area (Danakil depression, Afar region of Ethiopia). Hydrothermal activity in this region is part of the manifestations of the African rift. The Dallol hydrothermal site results from the interaction between the salty Red Sea waters, the runoff and the heat from a magmatic chamber located well below the 2,000 meters of salt. This makes this site unique as it develops its hydrothermal activity in salt-saturation conditions (up to 50%), creating a landscape with numerous colored hydrothermal chimneys made of salt (see figures).The water running out of those chimneys is very hot (up to 108 °C) and acidic, with pH values that can even be negative (up to -2.4!). Therefore, Dallol exhibits a combination of extreme physico-chemical parameters -salt saturation, acidity, high temperature- which is unique on Earth. Because of the presence of the African rift, this site has attracted the attention of geologists since long ago. However, nothing was known about the eventual presence of microbial life adapted to the multi-extreme conditions of this region. Nevertheless, because of the paucity of natural environments combining two or more of those physico-chemical extremes, the potential diversity of multi-extremophilic microorganisms remains largely unknown and poorly explored. This motivated our January 2016 expedition which allow to collect diverse water and mineral samples in a large variety of environments, with temperatures ranging from 40 to 108 °C, pH from -2.4 to 5, and salinity from 20 to 50%.The microbial diversity detection was carry out by D. Moreira and P. López-García laboratory in Osay (France) and the isolation of microorganisms is being done in my lab in the Universidad Autonoma of Madrid (Spain) using a variety of growth media designed to mimic the natural conditions found in Dallol.
During my stay in the Orsay laboratory, we advanced the characterization of the microbial diversity in the Dallol samples and the analysis of the physico-chemical (P-C) characteristics of the samples taken. Several sequences of archaeal 16S rDNAs were obtained. Most of them belong to the order Halobacteriales (Euryarchaeota), from the families Halobacteriacea and Haloferacaceae. Interestingly, several clones showed a large phylogenetic distance to the order Halobacteriales, indicating the presence of new species adapted to this particular environment.
The statistical analysis using P-C data measured in situ showed that the sampling points which are related with hydrothermal activity have high redox potential (Eh), very low pH and high concentrations of transition metals, while samples taken in areas remote from the Dallol dome contain relatively lower concentrations of those metals and higher concentrations of halogens as Cl and Br and alkaline earth metals as Mg, Ba and, especially, Ca.
The isolation of microorganisms and the study of diversity as well as the environmental characteristics of Dallol and surrounding areas is still in progress in our two laboratories.