Extreme Microbiology at Laguna Socompa: A High-Altitude Andean Lake (3570 m a.s.l.) in Salta, Argentina

Abstract

UV irradiation and the effect on microbial diversity and ecological impact was studied in Laguna Socompa, a hypersaline and moderate alkaline lake located at 3570 m a.s.l. at the base of the active Socompa volcano. The microbialites thriving on its shore are the highest on Earth, which exhibit an atypical microbial community with abundant representatives of Deinococcus–Thermus, Rhodobacteraceae, Desulfobacterales, and Spirochaetes. Their metagenome showed a high proportion of sequences depicting less than 80% identity to the best hit in the NCBI database, an indication of novel distant lineages. Several bacterial and archaeal strains from Socompa stromatolites were isolated, physiologically characterized, and subjected to genome pyrosequencing. Screening of the genomes of these strains, i.e., Exiguobacterium sp. S17, Sphingomonas sp. S17, Nesterenkonia sp. Act20, and Salinivibrio spp., yielded genes putatively encoding essential traits for survival under multiple extreme environmental conditions, e.g., high levels of UV radiation, elevated salinity, and the presence of poisonous arsenic concentrations. Thus, the study of microbes associated with Socompa stromatolites and their environment opens a window to the past by providing a modern analog to their Precambrian counterparts. On the other hand, they serve as models for further understanding of adaptation and the function of proteins under extremely harsh conditions, offering a biotechnological interest. In this chapter, we compared the microbial diversity of the different microbial niches found in Laguna Socompa (3570 m a.s.l.), i.e., lake water, sediments, stromatolites, and soil surrounding the lake.