The Hyperarid Core of the Atacama Desert, an Extremely Dry and Carbon Deprived Habitat of Potential Interest for the Field of Carbon Science

Azua‐Bustos, Armando; González-Silva, Carlos; Corsini, Gino

doi:10.3389/fmicb.2017.00993

Cited by 21 publications

(14 citation statements)

References 40 publications

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“…The microbial abundance in Schulze-Makuch et al (2018) was between 5 × 10 4 and 5 × 10 6 cells per gram of soils, generally lower than this study. The lower biomass and different PLFA compositions might be a result of the timing of sampling: they sampled 1 month after an even more massive rainfall (33.3 mm) in 2015 that could damage most microbial communities in a short period, with Proteobacteria and Firmicutes being the dominant survivors (Azua-Bustos et al, 2018;Fernandez-Martinez et al, 2019). Sampling of this study was performed 6 months after the heavy rainfall in 2017, and microbial communities could partly recover (Orlando et al, 2010;Armstrong et al, 2016;Uritskiy et al, 2019) to predisturbance abundance (Connon et al, 2007;Lester et al, 2007;Shirey, 2013;Valdivia-Silva et al, 2016;Finstad et al, 2017;Knief et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

“…The degradation of PLFAs reached a minimum when the mean annual precipitation is lower than 2 mm (Table 1). Moreover, the constant ratios of PLFA/TOC and PLFA/microbial P in the hyperarid Atacama Desert (Table 3) suggested that these microbial organics were derived directly from the native species, with negligible sources from organics in the form of seawater droplets over the Pacific Ocean (Wang et al, 2014;Azua-Bustos et al, 2017) transported by wind (Azua-Bustos et al, 2019). By applying PLFA analysis, it should be noted that not all PLFA components are known in every microbial species (Watzinger, 2015), and most individual PLFAs correspond with multiple microbial taxa and thus have a low taxonomic resolution (White et al, 1996;Olsson, 1999;Ruess and Chamberlain, 2010;Willers, 2016).…”

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Phospholipid biomarkers in Mars-analogous soils of the Atacama Desert

Shen

2020

International Journal of Astrobiology

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In Mars-analogous hyperarid soils of the Atacama Desert, phospholipid fatty acids (PLFAs) as the main component of biomembrane play a role in reliably determining viable microbes. PLFA analyses illustrated a rise of the microbial abundance (from 5.0 × 106 to 4.2 × 107 cells g−1) and biodiversity (from 7 to 15 different individual PLFAs) from the north hyperarid core of the Atacama Desert to the southern arid region. Abundant cyclopropyl PLFAs (47.2 ± 4.6%) suggested the resistance to oligotrophic and hypersaline environments by Atacama microbial communities. The southernmost arid site had the highest proportion (8.7%) of eukaryotic and fungal lipid biomarkers. Different precipitations (ranging from 0.7 to 2 mm year−1) in the hyperarid core exerted different effects on microbial biomass, PLFA diversity, bacteria and microeukaryotes. By principal component analysis (cumulative 74.6% of variance), the dominance of PLFA hydroxylation was associated with the microbial viability; bacteria rich in C16:0, C18:0 and C16:1ω9 favoured higher soil conductivity and nitrate; and other PLFAs contributed more to the organic content. Additionally by comparing the ratios of PLFAs to well-preserved organics (e.g., mineral-bound organic carbon and microbial phosphorus), I found that the degradation of PLFAs decreased to a minimum when the mean annual precipitation is lower than 2 mm. These findings may further specify identifiable biomarkers on Mars, if potentially extant Martian microbes possess comparable phospholipid membrane structure.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Phospholipid biomarkers in Mars-analogous soils of the Atacama Desert

Shen

2020

International Journal of Astrobiology

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“…Atacama soils are generally assumed to be C-limited with very slow carbon cycling [75], because of low organic C/N ratios. Phylogenetically ancient eukaryotes related to red algae [76,77], microbial biofilms [78], and specifically UV-resistant microorganisms [79,80] are also found to be present in the Atacama Desert, and could provide a persistent source of organic carbon for heterotrophy [81]. However, microbial C mineralization remains at low levels even with episodically enhanced moisture input associated with rainfall events [55,82].…”

Section: Nitrate Distribution and Effects On Microbial N Assimilationmentioning

confidence: 99%

Nitrates as a Potential N Supply for Microbial Ecosystems in a Hyperarid Mars Analog System

Shen

Zerkle

Stüeken

et al. 2019

Life

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Nitrate is common in Mars sediments owing to long-term atmospheric photolysis, oxidation, and potentially, impact shock heating. The Atacama Desert in Chile, which is the driest region on Earth and rich in nitrate deposits, is used as a Mars analog in this study to explore the potential effects of high nitrate levels on growth of extremophilic ecosystems. Seven study sites sampled across an aridity gradient in the Atacama Desert were categorized into 3 clusters—hyperarid, middle, and arid sites—as defined by essential soil physical and chemical properties. Intriguingly, the distribution of nitrate concentrations in the shallow subsurface suggests that the buildup of nitrate is not solely controlled by precipitation. Correlations of nitrate with SiO2/Al2O3 and grain sizes suggest that sedimentation rates may also be important in controlling nitrate distribution. At arid sites receiving more than 10 mm/yr precipitation, rainfall shows a stronger impact on biomass than nitrate does. However, high nitrate to organic carbon ratios are generally beneficial to N assimilation, as evidenced both by soil geochemistry and enriched culturing experiments. This study suggests that even in the absence of precipitation, nitrate levels on a more recent, hyperarid Mars could be sufficiently high to benefit potentially extant Martian microorganisms.

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“…Ancient aquatic species-related [44] microbial biofilms [45] and UV-resistant microorganisms [46,47] are discovered from the Atacama Desert. These organic sources should persist for a long time [48]. With little external input, leaching and subsurface decomposition [42], organic C in Atacama soils should mostly derive in situ.…”

Section: Introductionmentioning

confidence: 99%

Atmospheric Nitrate as a Potential Nutrient for Life on Mars

Shen¹,

Zerkle²,

Claire³

et al. 2019

Preprint

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Nitrate is rich in Mars sediments owing to long-term atmospheric photolysis, oxidation, and deposition coupled with a lack of leaching via rainfall. The Atacama Desert in Chile, which is similarly dry and rich in nitrate deposits, is used as a Mars analog in this study to explore the potential effects of high nitrate levels on microbial growth. Seven study sites sampled across an aridity gradient in the Atacama Desert were categorized into 3 clusters – hyperarid, intermediate, and arid sites, as defined by major elements in the regolith, associated biomass, and precipitation. Intriguingly, the distribution of nitrate concentrations in the shallow subsurface suggests that the buildup of nitrate is not solely controlled by precipitation. Correlations of nitrate with SiO2/Al2O3 and grain sizes suggest that sedimentation rates are also important in controlling nitrate distribution. At arid sites receiving more than 10 mm/yr precipitation, rainfall shows a stronger impact on biomass than nitrate does. However, high nitrate to organic carbon ratios are generally beneficial to N assimilation as evidenced both by soil geochemistry and enriched culturing experiments. This study suggests that even in the absence of precipitation on contemporary Mars, the nitrate levels are sufficiently high to benefit potentially extant Martian microorganisms.

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The Hyperarid Core of the Atacama Desert, an Extremely Dry and Carbon Deprived Habitat of Potential Interest for the Field of Carbon Science

Cited by 21 publications

References 40 publications

Phospholipid biomarkers in Mars-analogous soils of the Atacama Desert

Phospholipid biomarkers in Mars-analogous soils of the Atacama Desert

Nitrates as a Potential N Supply for Microbial Ecosystems in a Hyperarid Mars Analog System

Atmospheric Nitrate as a Potential Nutrient for Life on Mars

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