title: Stratified prokaryote network in the oxic-anoxic transition of a deep-sea halocline.
abstract: The chemical composition of the Bannock basin has been studied in some detail. We recently showed that unusual microbial populations, including a new division of Archaea (MSBL1), inhabit the NaCl-rich hypersaline brine. High salinities tend to reduce biodiversity, but when brines come into contact with fresher water the natural haloclines formed frequently contain gradients of other chemicals, including permutations of electron donors and acceptors, that may enhance microbial diversity, activity and biogeochemical cycling. Here we report a 2.5-m-thick chemocline with a steep NaCl gradient at 3.3 km within the water column betweeen Bannock anoxic hypersaline brine and overlying sea water. The chemocline supports some of the most biomass-rich and active microbial communities in the deep sea, dominated by Bacteria rather than Archaea, and including four major new divisions of Bacteria. Significantly higher metabolic activities were measured in the chemocline than in the overlying sea water and underlying brine; functional analyses indicate that a range of biological processes is likely to occur in the chemocline. Many prokaryotic taxa, including the phylogenetically new groups, were confined to defined salinities, and collectively formed a diverse, sharply stratified, deep-sea ecosystem with sufficient biomass to potentially contribute to organic geological deposits.
authors.affiliation: CoNISMa, Ulr Università degli Studi di Milano, DiSTAM, 20133 Milan, Italy. daniele.daffonchio@unimi.it
authors.forename: Daniele
authors.initials: D
authors.lastname: Daffonchio
authors.forename: Sara
authors.initials: S
authors.lastname: Borin
authors.forename: Tullio
authors.initials: T
authors.lastname: Brusa
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Brusetti
authors.forename: Paul W J J
authors.initials: PW
authors.lastname: van der Wielen
authors.forename: Henk
authors.initials: H
authors.lastname: Bolhuis
authors.forename: Michail M
authors.initials: MM
authors.lastname: Yakimov
authors.forename: Giuseppe
authors.initials: G
authors.lastname: D'Auria
authors.forename: Laura
authors.initials: L
authors.lastname: Giuliano
authors.forename: Danielle
authors.initials: D
authors.lastname: Marty
authors.forename: Christian
authors.initials: C
authors.lastname: Tamburini
authors.forename: Terry J
authors.initials: TJ
authors.lastname: McGenity
authors.forename: John E
authors.initials: JE
authors.lastname: Hallsworth
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Sass
authors.forename: Kenneth N
authors.initials: KN
authors.lastname: Timmis
authors.forename: Anastasios
authors.initials: A
authors.lastname: Tselepides
authors.forename: Gert J
authors.initials: GJ
authors.lastname: de Lange
authors.forename: Andreas
authors.initials: A
authors.lastname: Hübner
authors.forename: John
authors.initials: J
authors.lastname: Thomson
authors.forename: Soterios P
authors.initials: SP
authors.lastname: Varnavas
authors.forename: Francesco
authors.initials: F
authors.lastname: Gasparoni
authors.forename: Hans W
authors.initials: HW
authors.lastname: Gerber
authors.forename: Elisa
authors.initials: E
authors.lastname: Malinverno
authors.forename: Cesare
authors.initials: C
authors.lastname: Corselli
authors.forename: Jean
authors.initials: J
authors.lastname: Garcin
authors.forename: Boyd
authors.initials: B
authors.lastname: McKew
authors.forename: Peter N
authors.initials: PN
authors.lastname: Golyshin
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Lampadariou
authors.forename: Paraskevi
authors.initials: P
authors.lastname: Polymenakou
authors.forename: Daniele
authors.initials: D
authors.lastname: Calore
authors.forename: Stefano
authors.initials: S
authors.lastname: Cenedese
authors.forename: Fabio
authors.initials: F
authors.lastname: Zanon
authors.forename: Sven
authors.initials: S
authors.lastname: Hoog
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D001105:Archaea / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D044822:Biodiversity; D017753:Ecosystem; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D010100:Oxygen / Q000378:metabolism*; D011387:Prokaryotic Cells / Q000145:classification / Q000378:metabolism*; D012623:Seawater / Q000382:microbiology*; D012767:Ships; D014871:Water Microbiology
chemical_list: D010100:Oxygen