title: Anammox bacterial populations in deep marine hypersaline gradient systems.
abstract: To extend the knowledge of anaerobic ammonium oxidation (anammox) habitats, bacterial communities were examined in two hypersaline sulphidic basins in Eastern Mediterranean Sea. The 2 m thick seawater-brine haloclines of the deep anoxic hypersaline basins Bannock and L'Atalante were sampled in intervals of 10 cm with increasing salinity. (15)N isotope pairing incubation experiments showed the production of (29)N2 and (30)N2 gases in the chemoclines, ranging from 6.0 to 9.2 % salinity of the L'Atalante basin. Potential anammox rates ranged from 2.52 to 49.65 nmol N2 L(-1) day(-1) while denitrification was a major N2 production pathway, accounting for more than 85.5 % of total N2 production. Anammox-related 16S rRNA genes were detected along the L'Atalante and Bannock haloclines up to 24 % salinity, and the amplification of the hydrazine synthase genes (hzsA) further confirmed the presence of anammox bacteria in Bannock. Fluorescence in situ hybridisation and sequence analysis of 16S rRNA genes identified representatives of the marine anammox genus 'Candidatus Scalindua' and putatively new operational taxonomic units closely affiliated to sequences retrieved in marine environments that have documented anammox activity. 'Scalindua brodae' like sequences constituted up to 84.4 % of the sequences retrieved from Bannock. The anammox community in L'Atalante was different than in Bannock and was stratified according to salinity increase. This study putatively extends anammox bacterial habitats to extremely saline sulphidic ecosystems.
authors: Department of Food, Environmental and Nutritional Sciences, DeFENS, Università degli Studi di Milano, Via Celoria 2, Milan, Italy. sara.borin@unimi.it
authors: Sara
authors: S
authors: Borin
authors: Francesca
authors: F
authors: Mapelli
authors: Eleonora
authors: E
authors: Rolli
authors: Bongkeun
authors: B
authors: Song
authors: Craig
authors: C
authors: Tobias
authors: Markus C
authors: MC
authors: Schmid
authors: Gert J
authors: GJ
authors: De Lange
authors: Gert J
authors: GJ
authors: Reichart
authors: Stefan
authors: S
authors: Schouten
authors: Mike
authors: M
authors: Jetten
authors: Daniele
authors: D
authors: Daffonchio
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D000693:Anaerobiosis; D001421:Bacteria, Anaerobic / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D005798:Genes, Bacterial; D020459:Genes, rRNA; D006834:Hydrazines / Q000378:metabolism; D008522:Mediterranean Sea; D009587:Nitrogen Isotopes; D010084:Oxidation-Reduction; D010802:Phylogeny; D054712:Salinity; D012623:Seawater / Q000382:microbiology*; D017422:Sequence Analysis, DNA
chemical_list: D006834:Hydrazines; D009587:Nitrogen Isotopes; D000641:Ammonia