title: Bacterial communities and the nitrogen cycle in the gypsum soils of Cuatro Ciénegas Basin, coahuila: a Mars analogue.
abstract: The OMEGA/Mars Express hyperspectral imager identified gypsum at several sites on Mars in 2005. These minerals constitute a direct record of past aqueous activity and are important with regard to the search of extraterrestrial life. Gale Crater was chosen as Mars Science Laboratory Curiosity's landing site because it is rich in gypsum, as are some desert soils of the Cuatro Ciénegas Basin (CCB) (Chihuahuan Desert, Mexico). The gypsum of the CCB, which is overlain by minimal carbonate deposits, was the product of magmatic activity that occurred under the Tethys Sea. To examine this Mars analogue, we retrieved gypsum-rich soil samples from two contrasting sites with different humidity in the CCB. To characterize the site, we obtained nutrient data and analyzed the genes related to the N cycle (nifH, nirS, and nirK) and the bacterial community composition by using 16S rRNA clone libraries. As expected, the soil content for almost all measured forms of carbon, nitrogen, and phosphorus were higher at the more humid site than at the drier site. What was unexpected is the presence of a rich and divergent community at both sites, with higher taxonomic diversity at the humid site and almost no taxonomic overlap. Our results suggest that the gypsum-rich soils of the CCB host a unique microbial ecosystem that includes novel microbial assemblies.
authors.affiliation: Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Coyoacán, México D.F., México.
authors.forename: Nguyen E
authors.initials: NE
authors.lastname: López-Lozano
authors.forename: Luis E
authors.initials: LE
authors.lastname: Eguiarte
authors.forename: Germán
authors.initials: G
authors.lastname: Bonilla-Rosso
authors.forename: Felipe
authors.initials: F
authors.lastname: García-Oliva
authors.forename: Celeste
authors.initials: C
authors.lastname: Martínez-Piedragil
authors.forename: Christine
authors.initials: C
authors.lastname: Rooks
authors.forename: Valeria
authors.initials: V
authors.lastname: Souza
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D002133:Calcium Sulfate / Q000737:chemistry*; D016001:Confidence Intervals; D058440:Denitrification / Q000235:genetics; D018559:Exobiology; D015723:Gene Library; D005798:Genes, Bacterial / Q000235:genetics; D018535:Mars; D008800:Mexico; D059013:Microbial Consortia / Q000235:genetics; D008969:Molecular Sequence Data; D058458:Nitrogen Cycle / Q000235:genetics; D009586:Nitrogen Fixation / Q000235:genetics; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
chemical_list: D012336:RNA, Ribosomal, 16S; D012987:Soil; D002133:Calcium Sulfate