Characterization of microbiomes in the modern microbialite ecosystem of Pozo Bravo Lake, Argentina, using 16SrRNA amplicon sequencing

LENCINA, AGUSTINA INÉS; VIGNALE, FEDERICO A.; CARRIZO, DANIEL ; CASTILLEJOS SEPÚLVEDA, ANDREA; KLATT, JUDITH M; TURJANSKI, ADRIÁN G; GOMEZ, FERNANDO JAVIER; FARÍAS, MARÍA EUGENIA

Paris

Conferencia; Conference and Workshop. M-FED PARIS 2021; 2021

The Muséum National d?Histoire Naturelle

Pozo Bravo is a small (552.60 x 69 m), shallow (< 3 m), slightly alkaline (pH 8.4), hypersaline lake (165.5 mS/cm), placed at 3,300 m a.s.l in the western margin of the Salar de Antofalla, Catamarca Puna (northwest of Argentina). It harbors modern calcite microbialites that exhibit biostromal megastructures, domal, discoidal, tabular and compound macrostructures. The distinctive feature of Pozo Bravo microbialites is their composite internal structure characterized by a gradual transition from a thrombolitic core to dendrolitic structures and a sharply overlying stromatolitic layer. To expand our knowledge of the microbial ecosystems in Pozo Bravo, we have analyzed the prokaryotic community of the water, the lithifying mats and the microbialites by sequence analysis of 16S rRNA gene amplicons along an annual cycle.The water of Pozo Bravo is dominated by two phyla, Bacteroidetes and Proteobacteria, all over the year. The lithifying mats are dominated by Bacteroidetes, Proteobacteria and Cyanobacteria, but their abundances differ greatly between seasons. During spring and summer, there is an increase in theproportion of Cyanobacteria, Chloroflexi and Firmicutes, and a decrease in the proportion of Bacteroidetes and Proteobacteria. Whereas, in fall and winter, the opposite phenomenom is observed. Microbialites are dominated by Proteobacteria throughout the year. Cyanobacteria, Firmicutes, Bacteroidetes and Deinococcus-Thermus are also well-represented, but their abundances are highly variable between seasons. Cyanobacteria, Bacteroidetes and Deinococcus-Thermus are abundant in fall, while Firmicutes is abundant in winter and spring.This work expands our comprehension of the microbiomes in the modern microbialite ecosystem of Pozo Bravo and we hope it will provide the basis for further research.