Community Vertical Composition of the Laguna Negra Hypersaline Microbial Mat, Puna Region (Argentinean Andes)

Abstract

The Altiplano-Puna region is a high-altitude plateau in South America characterized by extreme conditions, including the highest UV incidence on Earth. The Laguna Negra is a hypersaline lake located in the Catamarca Province, northwestern Argentina, where stromatolites and other microbialites are found, and where life is mostly restricted to microbial mats. In this study, a particular microbial mat that covers the shore of the lake was explored, to unravel its layer-by-layer vertical structure in response to the environmental stressors therein. Microbial community composition was assessed by high-throughput 16S rRNA gene sequencing and pigment content analyses, complemented with microscopy tools to characterize its spatial arrangement within the mat. The top layer of the mat has a remarkable UV-tolerance feature, characterized by the presence of Deinococcus-Thermus and deinoxanthin, which might reflect a shielding strategy to cope with high UV radiation. Chloroflexi and Deltaproteobacteria were abundant in the second and third underlying layers, respectively. The bottom layer harbors copious Halanaerobiaeota. Subspherical aggregates composed of calcite, extracellular polymeric substances, abundant diatoms, and other microorganisms were observed all along the mat as the main structural component. This detailed study provides insights into the strategies of microbial communities to thrive under high UV radiation and hypersalinity in high-altitude lakes in the Altiplano-Puna region.

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Microbial diversity of the Tecozautla geyser, Mexico

“…Tamazawa et al (2012) indicated that ions (such as SO4 -2 ) could affect the morphology of microorganisms in the hot springs. The presence of ions may contribute to the complex range of colors in microbial mats (Boidi et al, 2022); this effect was observed in the microbial mats studied in the TG where various colors such as white, gray, yellow, red, pink, and green were observed, which coincides with the presence of sulfate ions, and other metals like Fe, Cd, Cu, Cr, and Al among others. org/10.22201/ib.20078706e.2023.94.5131 External factors can also influence the color of microbial mats.…”

Vertical organization of microbial communities in Salineta hypersaline wetland, Spain

“…Halorubrum and Natronomonas are known as aerobes (Mora-Ruiz et al, 2018), while Halapricum is a sulfate-reducing archaeon (Sorokin et al, 2022). Beside these genera from the dominant phyla, it is worth noting the presence of Halanaerobium (8.3%, representing 83.4% of the Halanaerobiaeota) and Truepera (8.5%, representing 99.8% of the Deinococcota), chemoorganotrophic strictly anaerobic and aerobic bacteria, respectively (Oren, 2015;Albuquerque et al, 2018), which are detected in hypersaline ecosystems (Boidi et al, 2022;Solchaga et al, 2022). Therefore, such observation indicated that the microbial community inhabiting the Salineta wetland is characteristic of extreme saline environments.…”