Metagenomic Sequencing of Big Soda Lake, Nevada

Modern carbonate tufas from Big Soda Lake (BSL), an alkaline lake in Nevada, exhibit rapid precipitation rates (>3 cm/yr) and host diverse microbial communities, but the role of microbes in tufa formation is unknown. We evaluated the microbial effects on carbonate precipitation that may influence fast deposition rates and whether rapidly precipitating tufas preserve biosignatures. Metagenomic sequencing showed that metabolisms capable of increasing carbonate saturation/precipitation (e.g., photosynthesis, ureolysis and bicarbonate transport) were present. Microbially-induced precipitation in BSL tufas may generate signatures preserved in the microfabric, such as micrite replacement of abiogenic carbonates and stromatolitic layers, that could serve as models for developing potential biosignatures on Earth and elsewhere.