**3.1 Microbial communities**

Studies on the microbiology of hypersaline lagoons in Chile are biased to lagoons in the Atacama Desert for various reasons. One the one hand, these lagoons provide a unique diversity of habitats to study microbial ecology and diversity as they spread in salt flats (Salars) at different altitudes, with varying salinities and ionic compositions [7, 23, 30]. On the other hand, and as previously said, the desert is a terrestrial Mars analog, and so a study case for researchers exploring the origin and limits of life on earth as a potential analog to life on Mars [21, 22]. Such diversity of microbial ecosystems (soil and brines) provides an opportunity to understand the physiological adaptations of microorganisms to extreme environmental conditions. A more practical argument has to do with the lithium richness of Salar de Atacama, the largest salt flat in the Atacama Desert, and so interest exists in evaluating the microbial diversity associated with this economically important mining process. The bacteria found in pools where brines are evaporated to concentrate lithium are expected to exhibit a range of unique molecular and metabolic capabilities to cope with high lithium concentration [31]. In a more general context, extremely salty lagoons both in Chile [32] and around the world are the source of metabolites and enzymes of biotechnological interest [12, 13]. Microbial mats are another bacterial ecosystem reported in Salar de Atacama, consisting of flat laminated communities with unicellular cyanobacteria (*Synechococcus* and *Cyanothece*), and filament forms (*Microccoleus*, *Oscillatoria*, *Gloeocapsa,* and *Gloeobacter*) [33].

The advent of culture-independent techniques such as the 16S rRNA gene sequencing has improved biodiversity studies in hypersaline lagoons, revealing hidden diversity not previously discovered by culturable-dependent techniques. This technique combined with the metagenomics [34] and other "omics" (transcriptomics, proteomics, metabolomics) has facilitated to get an integrated picture of the adaptive microbial response to extreme conditions and other aspects of microbial evolution such as antimicrobial resistance, pathogenesis, and the underlying genetic determinants of these capabilities [12].

Demergasso et al. [23] compared lagoons in Salars with strong altitude gradient (Llamará, Ascotán, and Atacama), qualitative differences in ionic compositions, and subject to different UV influence, finding predominance of phylum *Cytophaga-Flavobacterium-Bacteroides* (CFB) (now Bacteroidetes) and few Proteobacteria at high salinity and altitude (Salar de Ascotán), whereas diversity decreased in Salar de Atacama (in the pre-Andean Depression) and Llamará. Archaeal assemblages corresponded to uncultured haloarchaea distantly related to cultured strains obtained from thalassohaline environments. The study considered samples from 19 different environments of Céjas (or Céjar) (**Figure 1A**), Burro Muerto (**Figure 1B**), and Tebenquiche lagoons to conclude that athalassohaline environments are excellent sources of new microorganisms that are different from their counterparts in thalassohaline environments. A spatiotemporal study (three sites; summer and winter season) in Tebenquiche lagoon (**Figure 3**), the largest water body in Salar de Atacama [7], found abundance of genera belonging to phylum Bacteroidetes and Gammaproteobacteria, such as *Vibrio*, *Halomonas*, *Acinetobacter*, *Alteromonas*, *Psychrobacter*, and *Marinococcus*. The authors highlighted the remarkable novelty found as 16S rRNA gene sequences of Bacteroidetes. Another study on Bacteroidetes [35] evaluated brine and sediment samples from lagoons in Salar de Huasco, Salar

**63**

*Hypersaline Lagoons from Chile, the Southern Edge of the World*

*spatiotemporally and coexisting with the brine shrimp Artemia franciscana*.

de Ascotán, and also in Tebenquiche lagoon, finding high microbial diversity in Tebenquiche and Salar de Ascotán, whereas diversity decreased in Salar de Huasco. Most of the 16S rRNA gene sequences corresponded to the following genera

*Laguna Tebenquiche, the largest water body in Salar de Atacama harbors rich prokaryotic diversity varying* 

(Flavobacteriaceae): *Psychroflexus*, *Gillisia*, *Maribacter*, *Muricauda*, *Flavobacterium*, and *Salegentibacter*. The most abundant phylotype was related to *Psychroflexus* spp. A study of hypersaline wetlands in salars of the Altiplano at a higher altitude than those previously mentioned [36, 37], including Salar de Huasco and Salar de Ascotán, also showed significant differences in their microbial community attributed to habitat type and physicochemical properties of the lagoons. Bacteroidetes and Proteobacteria predominated with a smaller contribution of Firmicutes, Actinobacteria, Planctomycetes, Verrucomicrobia, Chloroflexi, Cyanobacteria,

The study of Azua-Bustos et al. [21] took advantage of unusual rain events in the hyperarid core of the Atacama Desert, which created temporal lagoons for some time. The authors observed that surface bacteria died due to osmotic stress but were able to isolate a newly identified species of *Halomonas* metabolically active and reproducing in the lagoon. Another study took soil samples at 2 m of depth in the core of the Atacama Desert [22], where life was not expected to exist, analyzed the samples with a life detector chip containing 300 antibodies, and found bacteria, Archaea, DNA, and exopolysaccharides. They identified members of the alpha, beta, gamma, and epsilon—Proteobacteria, Actinobacteria, Firmicutes, Acidobacteria, *Deinococcus*, Bacteroidetes, and Euryarchaeota. Back to hypersaline lagoons, the study of Cubillos et al. [31] assessed microbial communities in evaporating pools where lithium-rich brines pumped from beneath the Salar surface are concentrated (55.6% salinity) by lithium-exploiting companies. They found the archaeal family Halobacteriaceae and genera *Halovenus*, *Natronomonas*, *Haloarcula*, and *Halobacterium.* Instead, abundant families in natural brines were Rhodothermaceae and Staphylococcaceae. As these concentrated brines represent one of the most saline environment described, the authors concluded that the microorganisms found should shed further light on the

A study in our laboratory (Quiroz and Gajardo unpublished) (**Figure 4**) compared the microbial diversity of two Patagonian lagoons (Cisnes and de la Sal) with

*DOI: http://dx.doi.org/10.5772/intechopen.88438*

Acidobacteria, *Deinococcus-Thermus*.

**Figure 3.**

adaptive response to such extreme conditions.

**3.2 Microbial communities of Patagonian lagoons**

**Figure 3.**

*Lagoon Environments around the World - A Scientific Perspective*

(*Microccoleus*, *Oscillatoria*, *Gloeocapsa,* and *Gloeobacter*) [33].

determinants of these capabilities [12].

The advent of culture-independent techniques such as the 16S rRNA gene sequencing has improved biodiversity studies in hypersaline lagoons, revealing hidden diversity not previously discovered by culturable-dependent techniques. This technique combined with the metagenomics [34] and other "omics" (transcriptomics, proteomics, metabolomics) has facilitated to get an integrated picture of the adaptive microbial response to extreme conditions and other aspects of microbial evolution such as antimicrobial resistance, pathogenesis, and the underlying genetic

Demergasso et al. [23] compared lagoons in Salars with strong altitude gradient (Llamará, Ascotán, and Atacama), qualitative differences in ionic compositions, and subject to different UV influence, finding predominance of phylum *Cytophaga-Flavobacterium-Bacteroides* (CFB) (now Bacteroidetes) and few Proteobacteria at high salinity and altitude (Salar de Ascotán), whereas diversity decreased in Salar de Atacama (in the pre-Andean Depression) and Llamará. Archaeal assemblages corresponded to uncultured haloarchaea distantly related to cultured strains obtained from thalassohaline environments. The study considered samples from 19 different environments of Céjas (or Céjar) (**Figure 1A**), Burro Muerto (**Figure 1B**), and Tebenquiche lagoons to conclude that athalassohaline environments are excellent sources of new microorganisms that are different from their counterparts in thalassohaline environments. A spatiotemporal study (three sites; summer and winter season) in Tebenquiche lagoon (**Figure 3**), the largest water body in Salar de Atacama [7], found abundance of genera belonging to phylum Bacteroidetes and Gammaproteobacteria, such as *Vibrio*, *Halomonas*, *Acinetobacter*, *Alteromonas*, *Psychrobacter*, and *Marinococcus*. The authors highlighted the remarkable novelty found as 16S rRNA gene sequences of Bacteroidetes. Another study on Bacteroidetes [35] evaluated brine and sediment samples from lagoons in Salar de Huasco, Salar

**3.1 Microbial communities**

environmental conditions. Although both domains have coexisted and evolved under similar environmental pressures, the historical trend has been to consider them independently. However, later in this chapter, the *Artemia*-bacteria (microbiota) interaction is considered as an example of a symbiotic relationship.

Studies on the microbiology of hypersaline lagoons in Chile are biased to lagoons in the Atacama Desert for various reasons. One the one hand, these lagoons provide a unique diversity of habitats to study microbial ecology and diversity as they spread in salt flats (Salars) at different altitudes, with varying salinities and ionic compositions [7, 23, 30]. On the other hand, and as previously said, the desert is a terrestrial Mars analog, and so a study case for researchers exploring the origin and limits of life on earth as a potential analog to life on Mars [21, 22]. Such diversity of microbial ecosystems (soil and brines) provides an opportunity to understand the physiological adaptations of microorganisms to extreme environmental conditions. A more practical argument has to do with the lithium richness of Salar de Atacama, the largest salt flat in the Atacama Desert, and so interest exists in evaluating the microbial diversity associated with this economically important mining process. The bacteria found in pools where brines are evaporated to concentrate lithium are expected to exhibit a range of unique molecular and metabolic capabilities to cope with high lithium concentration [31]. In a more general context, extremely salty lagoons both in Chile [32] and around the world are the source of metabolites and enzymes of biotechnological interest [12, 13]. Microbial mats are another bacterial ecosystem reported in Salar de Atacama, consisting of flat laminated communities with unicellular cyanobacteria (*Synechococcus* and *Cyanothece*), and filament forms

**62**

*Laguna Tebenquiche, the largest water body in Salar de Atacama harbors rich prokaryotic diversity varying spatiotemporally and coexisting with the brine shrimp Artemia franciscana*.

de Ascotán, and also in Tebenquiche lagoon, finding high microbial diversity in Tebenquiche and Salar de Ascotán, whereas diversity decreased in Salar de Huasco. Most of the 16S rRNA gene sequences corresponded to the following genera (Flavobacteriaceae): *Psychroflexus*, *Gillisia*, *Maribacter*, *Muricauda*, *Flavobacterium*, and *Salegentibacter*. The most abundant phylotype was related to *Psychroflexus* spp. A study of hypersaline wetlands in salars of the Altiplano at a higher altitude than those previously mentioned [36, 37], including Salar de Huasco and Salar de Ascotán, also showed significant differences in their microbial community attributed to habitat type and physicochemical properties of the lagoons. Bacteroidetes and Proteobacteria predominated with a smaller contribution of Firmicutes, Actinobacteria, Planctomycetes, Verrucomicrobia, Chloroflexi, Cyanobacteria, Acidobacteria, *Deinococcus-Thermus*.

The study of Azua-Bustos et al. [21] took advantage of unusual rain events in the hyperarid core of the Atacama Desert, which created temporal lagoons for some time. The authors observed that surface bacteria died due to osmotic stress but were able to isolate a newly identified species of *Halomonas* metabolically active and reproducing in the lagoon. Another study took soil samples at 2 m of depth in the core of the Atacama Desert [22], where life was not expected to exist, analyzed the samples with a life detector chip containing 300 antibodies, and found bacteria, Archaea, DNA, and exopolysaccharides. They identified members of the alpha, beta, gamma, and epsilon—Proteobacteria, Actinobacteria, Firmicutes, Acidobacteria, *Deinococcus*, Bacteroidetes, and Euryarchaeota. Back to hypersaline lagoons, the study of Cubillos et al. [31] assessed microbial communities in evaporating pools where lithium-rich brines pumped from beneath the Salar surface are concentrated (55.6% salinity) by lithium-exploiting companies. They found the archaeal family Halobacteriaceae and genera *Halovenus*, *Natronomonas*, *Haloarcula*, and *Halobacterium.* Instead, abundant families in natural brines were Rhodothermaceae and Staphylococcaceae. As these concentrated brines represent one of the most saline environment described, the authors concluded that the microorganisms found should shed further light on the adaptive response to such extreme conditions.
