Unique Prokaryotic Consortia in Geochemically Distinct Sediments from Red Sea Atlantis II and Discovery Deep Brine Pools

Abstract

The seafloor is a unique environment, which allows insights into how geochemical processes affect the diversity of biological life. Among its diverse ecosystems are deep-sea brine pools - water bodies characterized by a unique combination of extreme conditions. The ‘polyextremophiles’ that constitute the microbial assemblage of these deep hot brines have not been comprehensively studied. We report a comparative taxonomic analysis of the prokaryotic communities of the sediments directly below the Red Sea brine pools, namely, Atlantis II, Discovery, Chain Deep, and an adjacent brine-influenced site. Analyses of sediment samples and high-throughput pyrosequencing of PCR-amplified environmental 16S ribosomal RNA genes (16S rDNA) revealed that one sulfur (S)-rich Atlantis II and one nitrogen (N)-rich Discovery Deep section contained distinct microbial populations that differed from those found in the other sediment samples examined. Proteobacteria, Actinobacteria, Cyanobacteria, Deferribacteres, and Euryarchaeota were the most abundant bacterial and archaeal phyla in both the S- and N-rich sections. Relative abundance-based hierarchical clustering of the 16S rDNA pyrotags assigned to major taxonomic groups allowed us to categorize the archaeal and bacterial communities into three major and distinct groups; group I was unique to the S-rich Atlantis II section (ATII-1), group II was characteristic for the N-rich Discovery sample (DD-1), and group III reflected the composition of the remaining sediments. Many of the groups detected in the S-rich Atlantis II section are likely to play a dominant role in the cycling of methane and sulfur due to their phylogenetic affiliations with bacteria and archaea involved in anaerobic methane oxidation and sulfate reduction.

Aerobic methanotrophic communities at the Red Sea brine-seawater interface

“…At ATII, samples were collected from the overlying water column from depths of 50, 200, 700, and 1500 m (Siam et al, 2012; Ferreira et al, 2014). The samples from the ATII overlying water column were used for the subtraction of common reads from the different brine/interface layers.…”

“…Pyrotag sequence analysis was performed as described in Siam et al (2012), using universal bacterial primers to amplify the V4–V6 regions of 16S rRNA (Siam et al, 2012). The 16S rRNA pyrosequencing analysis was performed three different times for each sample, and the results were merged.…”

Egypt's Red Sea coast: phylogenetic analysis of cultured microbial consortia in industrialized sites

“…The bacterial primers utilized in this study have been described (Siam et al, 2012). The amplicons recovered were subjected to pyrosequencing by 454 GS FLX Titanium technology (454 Life Sciences).…”

Probing connections between deep earth and surface processes in a land-locked ocean basin transformed into a giant saline basin: The Mediterranean GOLD project#

“…In this regard, GOLD is a unique opportunity to investigate the interacting effects of multiple extremes within and between diverse sedimentary strata. Potential microbial communities entombed in hypersaline deeply buried paleoenvironments will be compared to microbial communities that have been described in today's Mediterranean brines (Antunes et al, 2011;Siam et al, 2012;Maignien et al, 2012).…”