Characterization of bacterial diversity associated with microbial mats, gypsum evaporites and carbonate microbialites in thalassic wetlands: Tebenquiche and La Brava, Salar de Atacama, Chile

Abstract

In this paper, we report the presence of sedimentary microbial ecosystems in wetlands of the Salar de Atacama. These laminated systems, which bind, trap and precipitate mineral include: microbial mats at Laguna Tebenquiche and Laguna La Brava, gypsum domes at Tebenquiche and carbonate microbialites at La Brava. Microbial diversity and key biogeochemical characteristics of both lakes (La Brava and Tebenquiche) and their various microbial ecosystems (non-lithifying mats, flat and domal microbialites) were determined. The composition and abundance of minerals ranged from trapped and bound halite in organic-rich non-lithifying mats to aragonite-dominated lithified flat microbialites and gypsum in lithified domal structures. Pyrosequencing of the V4 region of the 16s rDNA gene showed that Proteobacteria comprised a major phylum in all of the microbial ecosystems studied, with a marked lower abundance in the non-lithifying mats. A higher proportion of Bacteroidetes was present in Tebenquiche sediments compared to La Brava samples. The concentration of pigments, particularly that of Chlorophyll a, was higher in the Tebenquiche than in La Brava. Pigments typically associated with anoxygenic phototrophic bacteria were present in lower amounts. Organic-rich, non-lithifying microbial mats frequently formed snake-like, bulbous structures due to gas accumulation underneath the mat. We hypothesize that the lithified microbialites might have developed from these snake-like microbial mats following mineral precipitation in the surface layer, producing domes with endoevaporitic communities in Tebenquiche and carbonate platforms in La Brava. Whereas the potential role of microbes in carbonate platforms is well established, the contribution of endoevaporitic microbes to formation of gypsum domes needs further investigation.

Genome comparison of two Exiguobacterium strains from high altitude andean lakes with different arsenic resistance: identification and 3D modeling of the Acr3 efflux pump

“…The high concentration of arsenic present in HAAL is strongly limiting not only for human life but also for growth of many microorganisms (Valko et al, 2005) and selects development of arsenic tolerant bacteria (Dib et al, 2008;Ordoñez et al, 2009). Different concentrations of arsenic (maximum values) were reported in these environments, 2.3 mg L −1 in Tebenquiche Lake (Farías et al, 2014), 9.1 mg L −1 in Salar de Llamara , 0.8-11.8 mg L −1 in Andean Lakes , 0.9-28 mg L −1 in salt lakes (Lara et al, 2012). Recently, in other HAAL higher values were detected, namely arsenic values between 18.5 and 33.8 mg L −1 were observed in Laguna Socompa ; these values are greater than the one reported for Mono Lake (200 µM HAsO −2 4 , approximately 19.8 mg L −1 As) (Oremland et al, 2004).…”

Niche for high abundant extremophilic microbial communities in an ancient crater

“…Many studies have investigated species compositions in soils of extreme environments (Bontognali et al 2010(Bontognali et al , 2012Farías et al 2014;Jay et al 2014); however, most of these have focused on the top layers or subsurface of soils from areas such as hypersaline sediments and Sabkhas (Kjeldsen et al 2007;Abdeljabbar et al 2013;Al-Najjar et al 2014), or saline/soda lakes (Sorokin et al 2014). In such environments, the biogeochemical cycle of nitrogen and sulphur is very important and shapes the microbial communities (Oren 2008;Al-Thani et al 2014).…”

“…Similarly, many studies have investigated the Atacama Desert (Desierto de Atacama) located as a plateau in South America along the Pacific coast to the west of the Andes mountains. It is the driest, non-polar and oldest desert on Earth (Farías et al 2014;Rasuk et al 2014Rasuk et al , 2016. Recent findings (Rasuk et al 2016) have indicated that a large proportion of 16S sequences could not be classified at the phylum level, which may indicate a new phylum is present in this Desert.…”

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

“…The salt composition is dominated by sulfate, chloride, sodium, and divalent cations [3] [5]. In spite of all of this, phototrophic and heterotrophic bacteria have recently been found in halite and gypsum evaporites and microbial mats [5] [6].…”

“…These ecosystems are characterized by extreme aridity, strong winds, scarce but torrential rainfall, high rates of evaporation, high solar radiation, extreme daily temperature changes, negative water balance, combined with a wide range of salinity [1] [3] [4]. The salt composition is dominated by sulfate, chloride, sodium, and divalent cations [3] [5]. In spite of all of this, phototrophic and heterotrophic bacteria have recently been found in halite and gypsum evaporites and microbial mats [5] [6].…”