title: Unveiling microbial life in new deep-sea hypersaline Lake Thetis. Part I: Prokaryotes and environmental settings.
abstract: In September 2008, an expedition of the RV Urania was devoted to exploration of the genomic richness of deep hypersaline anoxic lakes (DHALs) located in the Western part of the Mediterranean Ridge. Approximately 40 nautical miles SE from Urania Lake, the presence of anoxic hypersaline lake, which we named Thetis, was confirmed by swath bathymetry profiling and through immediate sampling casts. The brine surface of the Thetis Lake is located at a depth of 3258 m with a thickness of ≈ 157 m. Brine composition was found to be thalassohaline, saturated by NaCl with a total salinity of 348‰, which is one of highest value reported for DHALs. Similarly to other Mediterranean DHALs, seawater-brine interface of Thetis represents a steep pycno- and chemocline with gradients of salinity, electron donors and acceptors and posseses a remarkable stratification of prokaryotic communities, observed to be more metabolically active in the upper interface where redox gradient was sharper. [(14) C]-bicarbonate fixation analysis revealed that microbial communities are sustained by sulfur-oxidizing chemolithoautotrophic primary producers that thrive within upper interface. Besides microaerophilic autotrophy, heterotrophic sulfate reduction, methanogenesis and anaerobic methane oxidation are likely the predominant processes driving the ecosystem of Thetis Lake.
authors.affiliation: Institute for Coastal Marine Environment, CNR, Spianata S.Raineri 86, 98122 Messina, Italy.
authors.forename: Violetta
authors.initials: V
authors.lastname: La Cono
authors.forename: Francesco
authors.initials: F
authors.lastname: Smedile
authors.forename: Giovanni
authors.initials: G
authors.lastname: Bortoluzzi
authors.forename: Erika
authors.initials: E
authors.lastname: Arcadi
authors.forename: Giovanna
authors.initials: G
authors.lastname: Maimone
authors.forename: Enzo
authors.initials: E
authors.lastname: Messina
authors.forename: Mireno
authors.initials: M
authors.lastname: Borghini
authors.forename: Elvira
authors.initials: E
authors.lastname: Oliveri
authors.forename: Salvatore
authors.initials: S
authors.lastname: Mazzola
authors.forename: Stephan
authors.initials: S
authors.lastname: L'Haridon
authors.forename: Laurent
authors.initials: L
authors.lastname: Toffin
authors.forename: Lucrezia
authors.initials: L
authors.lastname: Genovese
authors.forename: Manuel
authors.initials: M
authors.lastname: Ferrer
authors.forename: Laura
authors.initials: L
authors.lastname: Giuliano
authors.forename: Peter N
authors.initials: PN
authors.lastname: Golyshin
authors.forename: Michail M
authors.initials: MM
authors.lastname: Yakimov
mesh_terms: D001105:Archaea / Q000145:classification / Q000235:genetics / Q000502:physiology*; D001419:Bacteria / Q000145:classification / Q000235:genetics; D018407:Bacterial Physiological Phenomena; D001669:Biochemical Phenomena / Q000235:genetics; D044822:Biodiversity; D008697:Methane / Q000378:metabolism; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D054712:Salinity; D012623:Seawater / Q000737:chemistry / Q000382:microbiology*
chemical_list: D012336:RNA, Ribosomal, 16S; D008697:Methane