Metagenomic profiling of halites from the Atacama Desert: an extreme environment with natural perchlorate does not promote high diversity of perchlorate reducing microorganisms

Abstract

We surveyed the presence of perchlorate-reducing microorganisms in available metagenomic data of halite environments from the Atacama Desert, an extreme environment characterized by high perchlorate concentrations, intense ultraviolet radiation, saline and oxidizing soils, and severe desiccation. While the presence of perchlorate might suggest a broad community of perchlorate reducers or a high abundance of a dominant taxa, our search reveals a scarce presence. In fact, we identified only one halophilic species, Salinibacter sp003022435, carrying the pcrA and pcrC genes, represented in low abundance. Moreover, we also discovered some napA genes and organisms carrying the nitrate reductase nasB gene, which hints at the possibility of cryptic perchlorate reduction occurring in these ecosystems. Our findings contribute with the knowledge of perchlorate reduction metabolism potentially occurring in halites from Atacama Desert and point towards promising future research into the perchlorate-reducing mechanism in Salinibacter, a common halophilic bacterium found in hypersaline ecosystems, whose metabolic potential remains largely unknown.

Keywords: Salinibacter; Atacama Desert; Halites; Metagenomics; Perchlorate reduction.