Aquatic Thermal Reservoirs of Microbial Life in a Remote and Extreme High Andean Hydrothermal System

Abstract

Hydrothermal systems are ideal to understand how microbial communities cope with challenging conditions. Lirima, our study site, is a polyextreme, high-altitude, hydrothermal ecosystem located in the Chilean Andean highlands. Herein, we analyze the benthic communities of three nearby springs in a gradient of temperature (42–72 °C represented by stations P42, P53, and P72) and pH, and we characterize their microbial diversity by using bacteria 16S rRNA (V4) gene metabarcoding and 16S rRNA gene clone libraries (bacteria and archaea). Bacterial clone libraries of P42 and P53 springs showed that the community composition was mainly represented by phototrophic bacteria (Chlorobia, 3%, Cyanobacteria 3%, at P42; Chlorobia 5%, and Chloroflexi 5% at P53), Firmicutes (32% at P42 and 43% at P53) and Gammaproteobacteria (13% at P42 and 29% at P53). Furthermore, bacterial communities that were analyzed by 16S rRNA gene metabarcoding were characterized by an overall predominance of Chloroflexi in springs with lower temperatures (33% at P42), followed by Firmicutes in hotter springs (50% at P72). The archaeal diversity of P42 and P53 were represented by taxa belonging to Crenarchaeota, Diapherotrites, Nanoarchaeota, Hadesarchaeota, Thaumarchaeota, and Euryarchaeota. The microbial diversity of the Lirima hydrothermal system is represented by groups from deep branches of the tree of life, suggesting this ecosystem as a reservoir of primitive life and a key system to study the processes that shaped the evolution of the biosphere.

Analysis of a Tropical Warm Spring Microbiota Using 16S rRNA Metabarcoding

“…The cold spring was slightly more diverse and contained one rare/unclassified member of the Chloroflexi phylum-GCA004 order, only found again in the midpoint of the cold spring. This ancient branch of the bacterial tree is normally thermophilic and found in hot springs and hydrothermal vents but was found in higher numbers in the colder regions [35]. They are also likely to adapt to changes in the physiochemical environment and are considered more primitive bacteria.…”

A Case Study for the Recovery of Authentic Microbial Ancient DNA from Soil Samples

“…with extreme environmental conditions (e.g., negative water balance, wide salinity range, and high daily temperature changes) [27,28]. Both sites are exposed to one of the highest solar radiation levels registered worldwide (>1200 W•m −2 ) [29,30], providing an unprecedented opportunity to examine how extremophilic microbes evolved over time.…”

“…Environmental microbial communities can have significant spatial and temporal variability at fine geographical scales and are highly heterogeneous [30,[66][67][68]. Therefore, researchers should be aware of these biases when subsampling soil or sediment in the aDNA laboratory and take several steps to increase reproducibility, maximize accuracy in reconstructions, and avoid biases during DNA extractions.…”

Revealing the Microbiome of Four Different Thermal Springs in Turkey with Environmental DNA Metabarcoding

“…The 16S rRNA gene, frequently used in microbiome analysis, is approximately 1500 base pairs long. This gene contains nine hypervariable regions that often vary between bacterial and archaeal species and can be used in species identification [ 20 ]. The 16S rRNA gene, a highly conserved region, is widely used in environmental microbiology, molecular evolution, microorganism classification, and phylogenetic analysis.…”