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

Abstract

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.

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

“…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. Curves represent the richness estimate at any given sampling intensity (sequences per sample).…”

“…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.…”

Desiccation- and Saline-Tolerant Bacteria and Archaea in Kalahari Pan Sediments

“…At a depth of 4.5–40 cm, up to 10% of the microbial community can be assigned to the phylum Planctomycetes , which comprises aerobic organoheterotrophic Phycisphaerae and Planctomycetaceae . Phycisphaerae were originally isolated from marine algae ( Fukunaga et al, 2009 ) and play an important role in the rhizome-associated concretions ( Fernandez et al, 2016 ). Planctomycetaceae are of particular interest for their eukaryotic-like cell structures and their properties of resistance to extreme environmental conditions ( Guo et al, 2012 ).…”

“…Acetothermia , Chloroflexi , and the family Bacteroidales of the phylum Bacteroidetes become more abundant. Members of Bacteroidetes are adapted to saline conditions and can be observed in a variety of hypersaline systems, including the Atacama Desert ( Fernandez et al, 2016 ; Schulze-Makuch et al, 2018 ), salterns ( Oren et al, 2009 ), microbial mats ( Sørensen et al, 2005 ), and evaporates ( Farías et al, 2014 ). Chloroflexi is also found in hypersaline environments, such as high-saline soils and hypersaline wastewater.…”

Characterization and Comparison of Microbial Soil Diversity in Two Andean Peatlands in Different States of Conservation-Vega Tocorpuri

“…Extracted DNA samples were amplified with F357 and R926 primers (NIH HMP Working Group, 2009). The reactions were performing according [81]. All sequences of the pyrosequencing runs were deposited in the NCBI Sequence Read Archive (SRA) database under the following accession number SRP120032.…”