Dataset Information

A microbial oasis in the hypersaline Atacama subsurface discovered by a life detector chip: implications for the search for life on Mars.

ABSTRACT: The Atacama Desert has long been considered a good Mars analogue for testing instrumentation for planetary exploration, but very few data (if any) have been reported about the geomicrobiology of its salt-rich subsurface. We performed a Mars analogue drilling campaign next to the Salar Grande (Atacama, Chile) in July 2009, and several cores and powder samples from up to 5?m deep were analyzed in situ with LDChip300 (a Life Detector Chip containing 300 antibodies). Here, we show the discovery of a hypersaline subsurface microbial habitat associated with halite-, nitrate-, and perchlorate-containing salts at 2?m deep. LDChip300 detected bacteria, archaea, and other biological material (DNA, exopolysaccharides, some peptides) from the analysis of less than 0.5?g of ground core sample. The results were supported by oligonucleotide microarray hybridization in the field and finally confirmed by molecular phylogenetic analysis and direct visualization of microbial cells bound to halite crystals in the laboratory. Geochemical analyses revealed a habitat with abundant hygroscopic salts like halite (up to 260?g kg(-1)) and perchlorate (41.13??g g(-1) maximum), which allow deliquescence events at low relative humidity. Thin liquid water films would permit microbes to proliferate by using detected organic acids like acetate (19.14??g g(-1)) or formate (76.06??g g(-1)) as electron donors, and sulfate (15875??g g(-1)), nitrate (13490??g g(-1)), or perchlorate as acceptors. Our results correlate with the discovery of similar hygroscopic salts and possible deliquescence processes on Mars, and open new search strategies for subsurface martian biota. The performance demonstrated by our LDChip300 validates this technology for planetary exploration, particularly for the search for life on Mars.

SUBMITTER: Parro V

PROVIDER: S-EPMC3242637 | biostudies-literature | 2011 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

A microbial oasis in the hypersaline Atacama subsurface discovered by a life detector chip: implications for the search for life on Mars.

Parro Victor V de Diego-Castilla Graciela G Moreno-Paz Mercedes M Blanco Yolanda Y Cruz-Gil Patricia P Rodríguez-Manfredi José A JA Fernández-Remolar David D Gómez Felipe F Gómez Manuel J MJ Rivas Luis A LA Demergasso Cecilia C Echeverría Alex A Urtuvia Viviana N VN Ruiz-Bermejo Marta M García-Villadangos Miriam M Postigo Marina M Sánchez-Román Mónica M Chong-Díaz Guillermo G Gómez-Elvira Javier J

Astrobiology 20111209 10

The Atacama Desert has long been considered a good Mars analogue for testing instrumentation for planetary exploration, but very few data (if any) have been reported about the geomicrobiology of its salt-rich subsurface. We performed a Mars analogue drilling campaign next to the Salar Grande (Atacama, Chile) in July 2009, and several cores and powder samples from up to 5 m deep were analyzed in situ with LDChip300 (a Life Detector Chip containing 300 antibodies). Here, we show the discovery of a ...[more]

PMID: 22149750

Similar Datasets

Project description:We report on a field demonstration of a rover-based drilling mission to search for biomolecular evidence of life in the arid core of the Atacama Desert, Chile. The KREX2 rover carried the Honeybee Robotics 1 m depth The Regolith and Ice Drill for Exploration of New Terrains (TRIDENT) drill and a robotic arm with scoop that delivered subsurface fines to three flight prototype instruments: (1) The Signs of Life Detector (SOLID), a protein and biomolecule analyzer based on fluorescence sandwich microarray immunoassay; (2) the Planetary In Situ Capillary Electrophoresis System (PISCES), an amino acid analyzer based on subcritical water extraction coupled to microchip electrophoresis analysis; and (3) a Wet Chemistry Laboratory cell to measure soluble ions using ion selective electrodes and chronopotentiometry. A California-based science team selected and directed drilling and sampling of three sites separated by hundreds of meters that included a light-toned basin area showing evidence of aqueous activity surrounded by a rocky desert pavement. Biosignatures were detected in basin samples collected at depths ranging from 20 to 80 cm but were not detected in the surrounding area. Subsurface stratigraphy of the units drilled was interpreted from drill sensor data as fine-scale layers of sand/clay sediments interspersed with layers of harder material in the basins and a uniform subsurface composed of course-to-fine sand in the surroundings. The mission timeline and number of commands sent to accomplish each activity were tracked. The deepest sample collected (80 cm) required 55 commands, including drilling and delivery to three instruments. Elapsed time required for drilling and sample handling was less than 3 hours to collect sample from 72 cm depth, including time devoted to recovery from a jammed drill. The experiment demonstrated drilling, sample transfer technologies, and instruments that accomplished successful detection of biomolecular evidence of life in one of the most biologically sparse environments on Earth.

Project description:One of the most promising planetary bodies that might harbor extraterrestrial life is Mars, given the presence of liquid water in the deep subsurface. The upper crust of Mars is mainly composed of >3.7-billion-year-old basaltic lava where heat-driven fluid circulation is negligible. The analogous crustal environment to the Martian subsurface is found in the Earth's oceanic crust composed of basaltic lava. The basaltic crust tends to cool down for 10-20-million-years after formation. However, microbial life in old cold basaltic lava is largely unknown even in the Earth's oceanic crust, because the lack of vigorous circulation prevents sampling of pristine crustal fluid from boreholes. Alternatively, it is important to investigate deep microbial life using pristine drill cores obtained from basaltic lava. We investigated a basaltic rock core sample with mineral-filled fractures drilled during Integral Ocean Drilling Project Expedition 329 that targeted 104-million-year-old oceanic crust. Mineralogical characterizations of fracture-infilling minerals revealed that fractures/veins were filled with Mg-rich smectite called saponite and calcium carbonate. The organic carbon content from the saponite-rich clay fraction in the core sample was 23 times higher than that from the bulk counterpart, which appears to be sufficient to supply energy and carbon sources to saponite-hosted life. Furthermore, a newly developed method to detect microbial cells in a thin-section of the saponite-bearing fracture revealed the dense colonization of SYBR-Green-I stained microbial cells spatially associated with saponite. These results suggest that the presence of saponite in old cold basaltic crust is favorable for microbial life. In addition to carbonaceous chondrite, saponite is a common product of low-temperature reactions between water and mafic minerals on Earth and Mars. It is therefore expected that deep saponite-bearing fractures could host extant life and/or the past life on Mars.

Project description:While many habitable niches on Earth are characterized by permanently cold conditions, little is known about the spatial structure of seasonal communities and the importance of substrate-cell associations in terrestrial cyroenvironments. Here we use the 16S rRNA gene as a marker for genetic diversity to compare two visually distinct but spatially integrated surface microbial mats on Axel Heiberg Island, Canadian high arctic, proximal to a perennial saline spring. This is the first study to describe the bacterial diversity in microbial mats on Axel Heiberg Island. The hypersaline springs on Axel Heiberg represent a unique analog to putative subsurface aquifers on Mars. The Martian subsurface represents the longest-lived potentially habitable environment on Mars and a better understanding of the microbial communities on Earth that thrive in analog conditions will help direct future life detection missions. The microbial mats sampled on Axel Heiberg are only visible during the summer months in seasonal flood plains formed by melt water and run-off from the proximal spring. Targeted-amplicon sequencing revealed that not only does the bacterial composition of the two mat communities differ substantially from the sediment community of the proximal cold spring, but that the mat communities are distinct from any other microbial community in proximity to the Arctic springs studied to date. All samples are dominated by Gammaproteobacteria: Thiotichales is dominant within the spring samples while Alteromonadales comprises a significant component of the mat communities. The two mat samples differ in their Thiotichales:Alteromonadales ratio and contribution of Bacteroidetes to overall diversity. The red mats have a greater proportion of Alteromonadales and Bacteroidetes reads. The distinct bacterial composition of the mat bacterial communities suggests that the spring communities are not sourced from the surface, and that seasonal melt events create ephemerally habitable niches with distinct microbial communities in the Canadian high arctic. The finding that these surficial complex microbial communities exist in close proximity to perennial springs demonstrates the existence of a transiently habitable niche in an important Mars analog site.

Project description:The Salar de Atacama in the Chilean Central Andes harbors unique microbial ecosystems due to extreme environmental conditions, such as high altitude, low oxygen pressure, high solar radiation, and high salinity. Combining X-ray diffraction analyses, scanning electron microscopy and molecular diversity studies, we have characterized twenty previously unexplored Andean microbial ecosystems in eight different lakes and wetlands from the middle-east and south-east regions of this salt flat. The mats and microbialites studied are mainly formed by calcium carbonate (aragonite and calcite) and halite, whereas the endoevaporites are composed predominantly of gypsum and halite. The carbonate-rich mats and microbialites are dominated by Bacteroidetes and Proteobacteria phyla. Within the phylum Proteobacteria, the most abundant classes are Alphaproteobacteria, Gammaproteobacteria and Deltaproteobacteria. While in the phylum Bacteroidetes, the most abundant classes are Bacteroidia and Rhodothermia. Cyanobacteria, Chloroflexi, Planctomycetes, and Verrucomicrobia phyla are also well-represented in the majority of these systems. Gypsum endoevaporites, on the contrary, are dominated by Proteobacteria, Bacteroidetes, and Euryarchaeota phyla. The Cyanobacteria phylum is also abundant in these systems, but it is less represented in comparison to mats and microbialites. Regarding the eukaryotic taxa, diatoms are key structural components in most of the microbial ecosystems studied. The genera of diatoms identified were Achnanthes, Fallacia, Halamphora, Mastogloia, Navicula, Nitzschia, and Surirella. Normally, in the mats and microbialites, diatoms form nano-globular carbonate aggregates with filamentous cyanobacteria and other prokaryotic cells, suggesting their participation in the mineral precipitation process. This work expands our knowledge of the microbial ecosystems inhabiting the extreme environments from the Central Andes region, which is important to ensure their protection and conservation.

Dataset Information

A microbial oasis in the hypersaline Atacama subsurface discovered by a life detector chip: implications for the search for life on Mars.

Publications

A microbial oasis in the hypersaline Atacama subsurface discovered by a life detector chip: implications for the search for life on Mars.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets