Towards determining the microbial diversity associated to spheroidal particles in a travertine system in the Puna of Argentina

MORS, R. AGUSTIN; GOMEZ, FERNANDO J.; MLEWSKI, CECILIA; ASTINI, RICARDO A.

Valparaíso

Congreso; 1er ISME AMÉRICA LATINA; 2019

Termas Los Hornos (TLH, Puna-Argentina) is a hydrothermal system at 3500 masl where extreme environmental conditions yields an extensive microbialitic system. Both physical and chemical processes influence carbonate precipitation. However, the microorganisms found over all the system could also have important implications. This work focuses in the diversity of microorganism associated to spheroidal mm-cm size particles found within shallow low-flow regime active travertine pools and their preserved biosignals. Bacterial and archaeal diversity was analyzed by16S rDNA IlluminaMiseq sequencing plus SEM and confocal microscopy observation of embedded samples. The carbonate microtextures were also analyzed. Our results show that Cyanobacteria was the most abundant phylum, follow by Proteobacteria (with alphaproteobacteria as the most abundant order) and Bacteroidetes. Phylas like Verrucomicrobia, Spirochaetes and Acidobacteria were also observed but in much lower abundance. SEM and CSLM show diatoms and abundant cyanobacteria. One of the most abundant cyanobacteria observed belongs to Rivularia genus that is morphologically similar to a new species isolated from Laguna Negra (LN), a hypersaline lake at 4500 masl. Rivularia Halophila and the consortia of microorganisms associated to their filaments was involved in the precipitation process of carbonates in the LN. Interesting, in TLH, Rivularia-like filaments was observed in petrographic thin sections of the spheroidal particles. This observation suggests that specific lineages may influence calcium-carbonate precipitation and could provide clues to identify lineages that specifically leave biosignatures in fossil records.