Stratified prokaryote network in the oxic-anoxic transition of a deep-sea halocline.
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.
Daffonchio
Daniele
D
CoNISMa, Ulr Università degli Studi di Milano, DiSTAM, 20133 Milan, Italy. daniele.daffonchio@unimi.it
Borin
Sara
S
Brusa
Tullio
T
Brusetti
Lorenzo
L
van der Wielen
Paul W J J
PW
Bolhuis
Henk
H
Yakimov
Michail M
MM
D'Auria
Giuseppe
G
Giuliano
Laura
L
Marty
Danielle
D
Tamburini
Christian
C
McGenity
Terry J
TJ
Hallsworth
John E
JE
Sass
Andrea M
AM
Timmis
Kenneth N
KN
Tselepides
Anastasios
A
de Lange
Gert J
GJ
Hübner
Andreas
A
Thomson
John
J
Varnavas
Soterios P
SP
Gasparoni
Francesco
F
Gerber
Hans W
HW
Malinverno
Elisa
E
Corselli
Cesare
C
Garcin
Jean
J
McKew
Boyd
B
Golyshin
Peter N
PN
Lampadariou
Nikolaos
N
Polymenakou
Paraskevi
P
Calore
Daniele
D
Cenedese
Stefano
S
Zanon
Fabio
F
Hoog
Sven
S
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
D010100:Oxygen