title: Partaking of Archaea to biogeochemical cycling in oxygen-deficient zones of meromictic saline Lake Faro (Messina, Italy).
abstract: We used a combination of molecular and microbiological approaches to determine the activity, abundance and diversity of archaeal populations inhabiting meromictic saline Lake Faro (Messina, Italy). Analysis of archaeal 16S rRNA, amoA, accA and hbd genes and transcripts revealed that sub- and anoxic layers of Lake Faro are primarily inhabited by the organisms related to the clusters of Marine Group I.1a of Thaumarchaeota frequently recovered from oxygen-depleted marine ecosystems. These organisms dominated the metabolically active archaea down to the bottom of the lake, indicating their adaptation to recurrent changes in the levels of water column hypoxia. The upper microaerobic layer of Lake Faro redoxcline has the maximal rates of dark primary production much lower than those of other previously studied pelagic redoxclines, but comparable to the values of meso- and bathypelagic areas of Mediterranean Sea. Application of bacterial inhibitors, especially azide, significantly declined the CO2 fixation rates in the low interface and monimolimnion, whereas archaea-specific inhibitor had effect only in upper part of the redoxcline. Based on these findings, we hypothesize that dark bicarbonate fixation in suboxic zone of Lake Faro results mainly from archaeal activity which is affected by the predicted lack in oxygen in lower layers.
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: Gina
authors.initials: G
authors.lastname: La Spada
authors.forename: Erika
authors.initials: E
authors.lastname: Arcadi
authors.forename: Francesco
authors.initials: F
authors.lastname: Placenti
authors.forename: Francesco
authors.initials: F
authors.lastname: Smedile
authors.forename: Gioacchino
authors.initials: G
authors.lastname: Ruggeri
authors.forename: Luigi
authors.initials: L
authors.lastname: Michaud
authors.forename: Carmen
authors.initials: C
authors.lastname: Raffa
authors.forename: Emilio
authors.initials: E
authors.lastname: De Domenico
authors.forename: Mario
authors.initials: M
authors.lastname: Sprovieri
authors.forename: Salvatore
authors.initials: S
authors.lastname: Mazzola
authors.forename: Lucrezia
authors.initials: L
authors.lastname: Genovese
authors.forename: Laura
authors.initials: L
authors.lastname: Giuliano
authors.forename: Vladlen Z
authors.initials: VZ
authors.lastname: Slepak
authors.forename: Michail M
authors.initials: MM
authors.lastname: Yakimov
mesh_terms: D000693:Anaerobiosis; D001105:Archaea / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D044822:Biodiversity; D002245:Carbon Dioxide / Q000378:metabolism; D017753:Ecosystem; D004783:Environmental Microbiology; D019766:Genes, Archaeal / Q000235:genetics; D007558:Italy; D060106:Lakes / Q000382:microbiology*; D008522:Mediterranean Sea; D008969:Molecular Sequence Data; D010100:Oxygen / Q000737:chemistry; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D054712:Salinity
chemical_list: D012336:RNA, Ribosomal, 16S; D002245:Carbon Dioxide; D010100:Oxygen