Bacterial Diversity in Microbial Mats and Sediments from the Atacama Desert

Rasuk, María Cecilia; Fernández, Ana Beatriz; Kurth, Daniel; Contreras, Manuel; Novoa, Fernando; Poiré, Daniel Gustavo; Farı́as, Marı́a Eugenia

doi:10.1007/s00248-015-0649-9

Cited by 66 publications

(49 citation statements)

References 78 publications

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“…However, given the limited presence of cyanobacterial as well as proteobacterial OTUs in our samples, it is plausible that, in addition to the Halobacteria discussed above, other organisms such as Acetothermia contribute to community CO 2 fixation in Tebenquiche. The scarcity of cyanobacteria in the current study corroborates earlier observations of a low cyanobacterial presence in mats and evaporites from the Salar de Atacama (Farías et al, 2013, 2014; Rasuk et al, 2014, 2016). However, we cannot rule out that the cyanobacterial community comprises a few species with high abundance, and high metabolic activity.…”

Section: Discussionsupporting

confidence: 92%

“…Several of the HAAL ecosystems have been described (Thiel et al, 2010; Farías et al, 2013; Gomez et al, 2014; Rasuk et al, 2016), but relatively little is known about the microbial diversity of the community in relation to biogeochemistry, especially that of the benthic ecosystems. The current investigation is the first in which the total microbial diversity was evaluated and interpreted in relation to the geochemical and physicochemical characteristics.…”

Section: Discussionmentioning

confidence: 99%

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Microbial Diversity in Sediment Ecosystems (Evaporites Domes, Microbial Mats, and Crusts) of Hypersaline Laguna Tebenquiche, Salar de Atacama, Chile

et al. 2016

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We combined nucleic acid-based molecular methods, biogeochemical measurements, and physicochemical characteristics to investigate microbial sedimentary ecosystems of Laguna Tebenquiche, Atacama Desert, Chile. Molecular diversity, and biogeochemistry of hypersaline microbial mats, rhizome-associated concretions, and an endoevaporite were compared with: The V4 hypervariable region of the 16S rRNA gene was amplified by pyrosequencing to analyze the total microbial diversity (i.e., bacteria and archaea) in bulk samples, and in addition, in detail on a millimeter scale in one microbial mat and in one evaporite. Archaea were more abundant than bacteria. Euryarchaeota was one of the most abundant phyla in all samples, and particularly dominant (97% of total diversity) in the most lithified ecosystem, the evaporite. Most of the euryarchaeal OTUs could be assigned to the class Halobacteria or anaerobic and methanogenic archaea. Planctomycetes potentially also play a key role in mats and rhizome-associated concretions, notably the aerobic organoheterotroph members of the class Phycisphaerae. In addition to cyanobacteria, members of Chromatiales and possibly the candidate family Chlorotrichaceae contributed to photosynthetic carbon fixation. Other abundant uncultured taxa such as the candidate division MSBL1, the uncultured MBGB, and the phylum Acetothermia potentially play an important metabolic role in these ecosystems. Lithifying microbial mats contained calcium carbonate precipitates, whereas endoevoporites consisted of gypsum, and halite. Biogeochemical measurements revealed that based on depth profiles of O2 and sulfide, metabolic activities were much higher in the non-lithifying mat (peaking in the least lithified systems) than in lithifying mats with the lowest activity in endoevaporites. This trend in decreasing microbial activity reflects the increase in salinity, which may play an important role in the biodiversity.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Microbial Diversity in Sediment Ecosystems (Evaporites Domes, Microbial Mats, and Crusts) of Hypersaline Laguna Tebenquiche, Salar de Atacama, Chile

et al. 2016

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“…This resulted in a mean of 266 (SE, 7.5) OTUs for the mat studied here compared to a mean of 256 (SE = 16.2) for the mats studied by Stanish et al (2013). These results are also similar to the studies of hypersaline mats of the Atacama Desert region (Farías et al 2013;Rasuk et al 2016;Fernandez et al 2016). For example, Fernandez et al (2016) reported between 121 Collector's curves or alpha-rarefaction plots for the 16S community (a), and the 18S community (b) in the microbial mat, defined at 97% SSU rDNA sequence identity.…”

Section: Resultssupporting

confidence: 88%

“…2, include Rhodobacter, Rubellimicrobium, and members of the Acetobacteraceae, including Roseococcus. Previous studies have implicated PPB (e.g., the Rhodospirillales) as playing important roles in high-elevation soils and sediments in the Rockies, Andes, and Himalayas (Demergasso et al 2010;King et al 2010a, b;Rasuk et al 2016;Schmidt et al 2011), including some of the highest elevation (>6000 m.a.s.l.) sites on Volcán Llullaillaco in the Atacama Desert (King et al 2010a, b).…”

Section: Resultsmentioning

confidence: 99%

Freeze–thaw revival of rotifers and algae in a desiccated, high-elevation (5500 meters) microbial mat, high Andes, Perú

et al. 2017

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This is the first study of the highest elevation cyanobacteria-dominated microbial mat yet described. The desiccated mat was sampled in 2010 from an ephemeral rock pool at 5500 m above sea level in the Cordillera Vilcanota of southern Perú. After being frozen for 6 years at -20 °C in the lab, pieces of the mat were sequenced to fully characterize both the 16 and 18S microbial communities and experiments were conducted to determine if organisms in the mat could revive and become active under the extreme freeze-thaw conditions that these mats experience in the field. Sequencing revealed an unexpectedly diverse, multi-trophic microbial community with 16S OTU richness comparable to similar, seasonally desiccated mats from the Dry Valleys of Antarctica and low elevation sites in the Atacama Desert region. The bacterial community of the mat was dominated by phototrophs in the Cyanobacteria (Nostoc) and the Rhodospirillales, whereas the eukaryotic community was dominated by predators such as bdelloid rotifers (Philodinidae). Microcosm experiments showed that bdelloid rotifers in the mat were able to come out of dormancy and actively forage even under realistic field conditions (diurnal temperature fluctuations of -12 °C at night to + 27 °C during the day), and after being frozen for 6 years. Our results broaden our understanding of the diversity of life in periodically desiccated, high-elevation habitats and demonstrate that extreme freeze-thaw cycles per se are not a major factor limiting the development of at least some members of these unique microbial mat systems.

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“…Similarly, many studies have investigated the Atacama Desert (Desierto de Atacama) located as a plateau in South America along the Pacific coast to the west of the Andes mountains. It is the driest, non-polar and oldest desert on Earth (Farías et al 2014;Rasuk et al 2014Rasuk et al , 2016. Recent findings (Rasuk et al 2016) have indicated that a large proportion of 16S sequences could not be classified at the phylum level, which may indicate a new phylum is present in this Desert.…”

Section: Introductionmentioning

confidence: 99%

Niche for high abundant extremophilic microbial communities in an ancient crater

Albokari

Al-Najjar

Mashhour

et al. 2017

International Journal of Astrobiology

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Al Wahbah Crater, located in a remote area in western Saudi Arabia as part of The Harrat extinct volcanic chain, is 2 km wide with a depth of 250 m. It is registered by the General Commission for Tourism and National Heritage as an ancient and archaeological site. The crater is subjected to extreme environmental conditions as its bottom is rarely subjected to rainfall and mudflows. Because of high temperature, high evaporation rates and extremely limited rainfall, the crater leaves behind dried thick white sodium phosphate crystals. Here, we studied the chemical composition and the microbial community composition using 16S rRNA pyrosequencing in different vertical layers (2, 20, 40, 60, 80 and 100 cm) of the crater sediment. Total sodium concentrations were 28 000-46 700 ppm and calcium levels were 31 400-56 500 ppm. In addition, samples were very sulphuric, with sulphate and sulphite levels exceeding 2157 ppm and 5.54 ppm, respectively. Ferric ions concentrations were <0.2 ppm, while nitrate, ammonium and nitrite levels were <2 ppm, 1.5 ppm and 0.05 ppm, respectively. Archaea dominated the surface and the bottom, while bacteria were most common at 20-60 cm. Extremely halophilic archaea and bacteria including Halorhabdus spp. Halorubrum spp., Salinibacter iranicus and Halorhodospira halophila were identified in all samples. Moreover, the relative abundance of Halanaerobiaceae accounted for 22% of the species in the top of the crater. S. iranicus and species belonging to Halorhabdus and Halorubrum that were identified between 60 and 100 cm could be considered as extreme organisms.

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Bacterial Diversity in Microbial Mats and Sediments from the Atacama Desert

Cited by 66 publications

References 78 publications

Microbial Diversity in Sediment Ecosystems (Evaporites Domes, Microbial Mats, and Crusts) of Hypersaline Laguna Tebenquiche, Salar de Atacama, Chile

Microbial Diversity in Sediment Ecosystems (Evaporites Domes, Microbial Mats, and Crusts) of Hypersaline Laguna Tebenquiche, Salar de Atacama, Chile

Freeze–thaw revival of rotifers and algae in a desiccated, high-elevation (5500 meters) microbial mat, high Andes, Perú

Niche for high abundant extremophilic microbial communities in an ancient crater

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