title: Diversity of methanogens and sulfate-reducing bacteria in the interfaces of five deep-sea anoxic brines of the Red Sea.
abstract: Oceanic deep hypersaline anoxic basins (DHABs) are characterized by drastic changes in physico-chemical conditions in the transition from overlaying seawater to brine body. Brine-seawater interfaces (BSIs) of several DHABs across the Mediterranean Sea have been shown to possess methanogenic and sulfate-reducing activities, yet no systematic studies have been conducted to address the potential functional diversity of methanogenic and sulfate-reducing communities in the Red Sea DHABs. Here, we evaluated the relative abundance of Bacteria and Archaea using quantitative PCR and conducted phylogenetic analyses of nearly full-length 16S rRNA genes as well as functional marker genes encoding the alpha subunits of methyl-coenzyme M reductase (mcrA) and dissimilatory sulfite reductase (dsrA). Bacteria predominated over Archaea in most locations, the majority of which were affiliated with Deltaproteobacteria, while Thaumarchaeota were the most prevalent Archaea in all sampled locations. The upper convective layers of Atlantis II Deep, which bear increasingly harsh environmental conditions, were dominated by members of the class Thermoplasmata (Marine Benthic Group E and Mediterranean Sea Brine Lakes Group 1). Our study revealed unique microbial compositions, the presence of niche-specific groups, and collectively, a higher diversity of sulfate-reducing communities compared to methanogenic communities in all five studied locations.
authors.affiliation: Red Sea Research Center, King Abdullah University of Science and Technology, 23955-6900, Thuwal, Saudi Arabia.
authors.forename: Yue
authors.initials: Y
authors.lastname: Guan
authors.affiliation: Red Sea Research Center, King Abdullah University of Science and Technology, 23955-6900, Thuwal, Saudi Arabia.
authors.forename: Tyas
authors.initials: T
authors.lastname: Hikmawan
authors.affiliation: Computational Bioscience Research Centre, King Abdullah University of Science and Technology (KAUST), 23955-6900, Thuwal, Saudi Arabia.
authors.forename: André
authors.initials: A
authors.lastname: Antunes
authors.affiliation: Red Sea Research Center, King Abdullah University of Science and Technology, 23955-6900, Thuwal, Saudi Arabia.
authors.forename: David
authors.initials: D
authors.lastname: Ngugi
authors.affiliation: Red Sea Research Center, King Abdullah University of Science and Technology, 23955-6900, Thuwal, Saudi Arabia. Electronic address: uli.stingl@kaust.edu.sa.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Stingl
mesh_terms: D001105:Archaea / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D001419:Bacteria / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D020564:Deltaproteobacteria / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D014644:Genetic Variation; D019156:Indian Ocean; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*; D013431:Sulfates / Q000378:metabolism*
chemical_list: D012336:RNA, Ribosomal, 16S; D013431:Sulfates
keywords: Biodiversity; Brine pools; Hypersaline environments; Methanogens; Sulfate reducers