A wide variety of putative extremophiles and large beta-diversity at the Mars Desert Research Station (Utah)

Abstract

Humankind's innate curiosity makes us wonder whether life is or was present on other planetary bodies such as Mars. The EuroGeoMars 2009 campaign was organized at the Mars Desert Research Station (MDRS) to perform multidisciplinary astrobiology research. MDRS in southeast Utah is situated in a cold arid desert with mineralogy and erosion processes comparable to those on Mars. Insight into the microbial community composition of this terrestrial Mars analogue provides essential information for the search for life on Mars: including sampling and life detection methodology optimization and what kind of organisms to expect. Soil samples were collected from different locations. Culture-independent molecular analyses directed at ribosomal RNA genes revealed the presence of all three domains of life (Archaea, Bacteria and Eukarya), but these were not detected in all samples. Spiking experiments revealed that this appears to relate to low DNA recovery, due to adsorption or degradation. Bacteria were most frequently detected and showed high alpha-and beta-diversity. Members of the Actinobacteria, Proteobacteria, Bacteroidetes and Gemmatimonadetes phyla were found in the majority of samples. Archaea alpha-and beta-diversity was very low. For Eukarya, a diverse range of organisms was identified, such as fungi, green algae and several phyla of Protozoa. Phylogenetic analysis revealed an extraordinary variety of putative extremophiles, mainly Bacteria but also Archaea and Eukarya. These comprised radioresistant, endolithic, chasmolithic, xerophilic, hypolithic, thermophilic, thermoacidophilic, psychrophilic, halophilic, haloalkaliphilic and alkaliphilic micro-organisms. Overall, our data revealed large difference in occurrence and diversity over short distances, indicating the need for high-sampling frequency at similar sites. DNA extraction methods need to be optimized to improve extraction efficiencies.

Abiotic Factors Shape Microbial Diversity in Sonoran Desert Soils

“…The core microbiome of this study has a different composition than those reads found only in individual samples, with the aforementioned preponderance of Thermoprotei. This is perhaps not unexpected, as Crenarchaeota contains radio-and thermotolerant species detected previously in other extreme environments, including desert soils (16,21), hot springs (75), permafrost (80), and marine environments near the Sonoran Desert (8). The rare OTUs appear to be relatively similar in terms of the proportion of various phyla between sample sites.…”

“…PCR amplification of the 16S rRNA gene and subsequent pyrosequencing were carried out at the Australian Centre for Ecogenomics (http://www.ecogenomic.org/) as previously described (21). Briefly, broad-specificity oligonucleotide primers 926F (F stands for forward) (5=-AAACTYAAAKGAATTGACGG-3=) and 1392R (R stands for reverse) (5=-ACGGGCGGTGTGTRC-3=) containing multiplex identifiers and LibL adaptor sequences (see Table S1 in the supplemental material) were used to generate amplicons spanning the hypervariable regions of the 16S rRNA gene from V6 to V9 (22).…”

The Significance of Microbe-Mineral-Biomarker Interactions in the Detection of Life on Mars and Beyond

“…MDRS, in Utah, is an arid, oxidizing environment with high temperatures during the day and low temperatures at night. MDRS has a mineralogy comparable to that found on Mars and a patchy distribution of biomarkers and microorganisms (Clarke and Stoker, 2011;Direito et al, 2011;Ehrenfreund et al, 2011;Martins et al, 2011). Parts of Mars may have been highly acidic and saline in the past, resembling conditions currently found at Río Tinto, Spain.…”

Exploration of Deinococcus‐Thermus molecular diversity by novel group‐specific PCR primers

“…); the Mars desert research station (UT; Direito et al. ); sunlight‐exposed biofilms from Chernobyl (Ukraine; Ragon et al. ); and saline biological desert crusts (China; Li et al.…”