Unveiling Local Radiation Events through Metagenome Assembled Genomes of Archaea and Bacteria in Hypersaline Microbial Mats from the Archean Domes Site, Cuatro Cienegas, Coahuila, Mexico

Abstract A comprehensive study was conducted in the Cuatro Cienegas Basin (CCB) in Coahuila, Mexico, known for its remarkable microbiological diversity and unique physicochemical properties. The ″Archaean Domes ″ (DA) in the CCB are hypersaline, non-lithifying microbial mats. This study focused on analyzing the small domes and circular structures formed in DA through metagenome assembly genomes (MAGs) with the aim of finding new microorganisms and providing information on the tree of life in a place as diverse as the CCB. In total, 329 MAGs were identified, including 52 archaea and 277 bacteria. Remarkably, 30 Archaea and 154 Bacteria could not be classified at the genus level, highlighting the remarkable diversity of CCB. The CCBs showed significant diversity at the phylum level, with Proteobacteria being the most abundant, followed by Euryarchaeota, Firmicutes, Bacteroidetes, Actinobacteria, Cyanobacteria, Spirochaetes, Chloroflexi, Planctomycetes, Candidatus Parvarchaeota, Verrucomicrobia, Balneolaeota, Nitrospirae, and Tenericutes. Subsequently, the MAGs were classified into a phylogenetic tree. In Archaea, monophyletic groups MAGs belonged to the phyla Archaeoglobi, Candidatus Aenigmarchaeota, Candidatus Nanoarchaeota, Candidatus Lokiarchaeota, and Halobacteriota. Among the Bacteria, monophyletic groups were identified as well, including Spirochaetes, Proteobacteria, Planctomycetota, Actinobacteria, Verrucomicrobiota, Bacteroidetes, Bipolaricaulota, Desulfobacterota, and Cyanobacteria. These monophyletic clusters may indicate radiation events that are likely influenced by geographical isolation as well as extreme environmental conditions reported in AD pond like phosphorus deficiency (122:42:1 C:N:P), fluctuating pH and a salinity of 5.28%