Microbial Communities From the World's Largest Lithium Reserve, Salar de Atacama, Chile: Life at High LiCl Concentrations

Abstract

Salar de Atacama is one of the largest global reservoirs of natural lithium brines (mean lithium concentration = 1,500 ppm), enabling Chile to be a leading producer of lithium products. This large salar (3,000 km 2 ), located in the Atacama Desert at 2,300 m above sea level, is dominated by microorganisms; however, little is known about the microbes present in the brines associated with this economically important mining process. Here we study lithium as a modulator of microbial richness and diversity in brines representing natural conditions (34.7% salinity) and conditions prior to lithium production with a concentrated brine (55.6% salinity). Brines only supported a single archaeal family (Halobacteriaceae): natural brines included the archaeal genera Halovenus, Natronomonas, Haloarcula, and Halobacterium. Concentrated brines included the archaeal genera Halovenus, Halobacterium, and Halococcus. The most abundant bacterial families in natural brine were Rhodothermaceae and Staphylococcaceae; Xanthomonadaceae dominated the bacterial community in the concentrated brine. A comparison of entire microbial community (Archaea and Bacteria) revealed that only seven operational taxonomic units were shared between samples, all of which were Archaea. Further, our results showed that Bacteria were phylogenetically more diverse and rich in the concentrated brine, while archaeal diversity was maximized in the natural brine. The concentrated lithium brines of the Salar de Atacama represent one of the most saline environments described to date (dominated by LiCl). We suggest that elevated concentrations of lithium could greatly modulate microbial diversity and give insights into the adaptive biology of microorganisms required to cope with extremely high concentrations of salts that extend beyond that of NaCl, a far more commonly studied salt.Plain Language Summary Lithium is a main component of many of the batteries that we rely on for our daily use. In the last years, nearly 40% of all lithium obtained globally was from a single fragile salt-lake ecosystem: Salar de Atacama in the Atacama Desert of northern Chile. This salar has extremely saline waters called brines (dominated by NaCl, aka table salt), which are naturally highly concentrated in lithium and concentrated in evaporation ponds. In total, concentrated brines has a salinity of 55.6% (ocean salinity = 0.3%), representing one of the most saline environments described on Earth to date (dominated by lithium chloride). Our research has shown that concentrated brines support life and are dominated by hundreds of species of microorganisms. Due to saline stress these "extremophiles" have developed very special (and previously undescribed) strategies to survive in this lithium soup. These results have implications beyond Earth: they have marked implications for our understanding for the potential for life on Mars, where liquid water is known to occur as brine. Although lithium production has clear economic importance, our results show that we should consider how we will pre...

Andean hypersaline lakes in the Atacama Desert, northern Chile: Between lithium exploitation and unique biodiversity conservation

“…Indeed, lithium has become one of the world's hottest commodity, which explains why Tianqui recently closed a US$ 4.3 million deal to buy a 24% stake in Chile's SQM, one of the world's largest lithium producer from brine, which is a highly cost-effective business. Likewise, for those studying the origin and limits of life on Earth as an analog to life on Mars (Azua-Bustos et al, 2018), searching microorganisms with medical and biotechnological applications or for those looking for new species in lithium evaporating pools (Cubillos et al, 2018). For example, the Salar is a target area for researchers all over the world looking to better understand the ecology of extreme ecosystems (Demergasso et al, 2004;Gajardo & Beardmore, 2012).…”

“…Salar de Atacama has longstanding arid climate stability (aridity index: 0, 0326) with evaporation rate (1,440 mm/year) exceeding rainfall (39 mm/year) (Munk et al, 2016; see also Cubillos et al, 2018). Salar de Atacama has longstanding arid climate stability (aridity index: 0, 0326) with evaporation rate (1,440 mm/year) exceeding rainfall (39 mm/year) (Munk et al, 2016; see also Cubillos et al, 2018).…”

“…The Salar (3,067 km 2 ), located over 2,300 m above sea level in the Altiplano-Puna region of the Central Andes, is flanked by the Pacific Ocean to the west and the mountains to the east. It contains the world's largest lithium reserves and exploitation from brines (Cubillos, Aguilar, Grágeda, & Dorador, 2018) with the highest average lithium concentration: 1,400 mg/L; range: 900-7,000 (Munk et al, 2016).…”

“…For example, the Salar is a target area for researchers all over the world looking to better understand the ecology of extreme ecosystems (Demergasso et al, 2004;Gajardo & Beardmore, 2012). Likewise, for those studying the origin and limits of life on Earth as an analog to life on Mars (Azua-Bustos et al, 2018), searching microorganisms with medical and biotechnological applications or for those looking for new species in lithium evaporating pools (Cubillos et al, 2018). Except in Tibet and Andean countries like Perú (Laguna Lagunita) and Bolivia (Lake Uyuni, another huge but less exploited lithium reservoir, see Draper, 2019), there are no other salty lagoons over 2,300 m of altitude which makes them extremely vulnerable to water or brine diversion due to aridity of the place (evaporation largely exceeding rainfall).…”

“…Despite the international recognition of these hypersaline lagoons and wetlands as invaluable natural resources, conservation efforts are needed to maintain their intrinsic value and biodiversity under a future scenario of continued or even increased aridity, water shortage and increased brine diversion by lithium companies. Salar de Atacama has longstanding arid climate stability (aridity index: 0, 0326) with evaporation rate (1,440 mm/year) exceeding rainfall (39 mm/year) (Munk et al, 2016; see also Cubillos et al, 2018). Nevertheless, highly unusual summer rains (December-March) have flooded the area in recent years (Azua-Bustos et al, 2018).…”