Salar del Hombre Muerto, source of lithium-tolerant bacteria

Abstract

The Salar del Hombre Muerto is a flat salt with great microbial activity despite the existing extreme conditions like high altitude, lack of water, low level of oxygen, high radiation and high concentration of sodium and lithium chloride. Despite these unfavorable conditions, we found microbial diversity with the presence of fungi, algae, and bacteria. From aqueous solutions and soil samples, a total of 238 bacteria were isolated and 186 of them were able to grow in the presence of salt. About 30% of the strains showed the ability to grow in solid medium proximally to a LiCl solution close to saturation (636 g/L). These isolates were characterized taking into account the morphology, Gram stain, ability to form biofilms and to produce pigments, and mainly according to the tolerance against lithium chloride. Bacillus was predominant among the most tolerant 26 microorganisms found, followed by Micrococcus and Brevibacterium. Members of the genera Kocuria, Curtobacterium and Halomonas were also represented among the bacteria with tolerance to 30 and 60 g/L of LiCl in defined liquid medium. All the capacities found in these microorganisms make them extremely interesting for biotechnological applications.

Potential of Bioremediation and PGP Traits in Streptomyces as Strategies for Bio-Reclamation of Salt-Affected Soils for Agriculture

“…Exopolysaccharides are carbohydrate polymers of great structural diversity according to the different functions they have. Structural EPS such as cellulose are responsible for the interactions between cells and their cells with the surface [6] and their composition varies not only with the microorganism, but also with the environmental conditions that favor its growth [88]: availability of oxygen and nutrients, temperature, pH, and presence of stressors such as heavy metals in addition to high salt concentrations. Even when generated by the same species, EPS can have different compositions [6].…”

“…Within the group of actinomycetes, Amycolatopsis sp. AB0 stands out because it forms an EPS in the presence of copper [74], and in the extreme environment the "Salar del Hombre Muerto" actinomycetes with the ability to produce EPS in the presence of lithium were isolated [88]. Recently, Moraga et al [6] isolated Streptomyces spp.…”

Complete Genome Sequence and Methylome Analysis of Micrococcus luteus SA211, a Halophilic, Lithium-Tolerant Actinobacterium from Argentina

“…We isolated an extremophilic strain of M. luteus designated SA211 from soil of the hypersaline Salar del Hombre Muerto in northwestern Argentina that can grow in media containing high concentrations of salts (up to 4 M NaCl), including lithium (up to 30 g/liter in defined liquid media) (4). Genome sequencing was performed to establish methods for its use in biotechnological applications.…”

“…Genomic DNA was isolated from a culture of M. luteus SA211 grown to late exponential phase at 30°C and 200 rpm in modified nutrient broth (MNB) (4) using the following procedure. Cells were harvested by centrifugation at 10,000 rpm for 10 min (Eppendorf Centrifuge, 5415R) and lysed by adding 800 μl of lysozyme (10 mg/ml) in buffer (75 mM NaCl, 25 mM EDTA, 20 mM Tris, pH 7.5) and incubation for 2 h at 37°C (5).…”

Insights Into the Microbiology of the Chaotropic Brines of Salar de Atacama, Chile

“…In particular, bacteria belonging to the Bacillales order are found in almost every environment on Earth from the stratosphere (Sass et al, 2008), through to NaCl-hypersaline environments, such as salterns (Garabito et al, 1998), saline soils (Zahran, 1997), freshwater lakes (Bagheri et al, 2012; Amoozegar et al, 2014, 2016), and even in alkaline lakes (Weisser and Trüper, 1985). Moreover, they have been isolated from brines with different chemical composition including MgCl 2 (Hallsworth et al, 2007; Sass et al, 2008), Na 2 CO 3 (Jones et al, 1998), and NaCl/LiCl (Rodríguez-Contreras et al, 2013; Martínez et al, 2018). There is an increasing awareness that saline environments include both natural and artificial environments, and extend beyond those dominated by NaCl, with microbial life being reported at high salinities of other salts or even different pH as Na 2 CO 3 (Imhoff et al, 1979; Banciu and Muntyan, 2015), CaCl 2 (Dickson et al, 2013), MgCl 2 (Yakimov et al, 2015), LiCl (Cubillos et al, 2018) or acid (Benison, 2008, 2019) and basic brines (Samylina et al, 2014).…”