title: Temporal dynamics of active Archaea in oxygen-depleted zones of two deep lakes.
abstract: Deep lakes are of specific interest in the study of archaeal assemblages as chemical stratification in the water column allows niche differentiation and distinct community structure. Active archaeal community and potential nitrifiers were investigated monthly over 1 year by pyrosequencing 16S rRNA transcripts and genes, and by quantification of archaeal amoA genes in two deep lakes. Our results showed that the active archaeal community patterns of spatial and temporal distribution were different between these lakes. The meromictic lake characterized by a stable redox gradient but variability in nutrient concentrations exhibited large temporal rearrangements of the dominant euryarchaeal phylotypes, suggesting a variety of ecological niches and dynamic archaeal communities in the hypolimnion of this lake. Conversely, Thaumarchaeota Marine Group I (MGI) largely dominated in the second lake where deeper water layers exhibited only short periods of complete anoxia and constant low ammonia concentrations. Investigations conducted on archaeal amoA transcripts abundance suggested that not all lacustrine Thaumarchaeota conduct the process of nitrification. A high number of 16S rRNA transcripts associated to crenarchaeal group C3 or the Miscellaneous Euryarchaeotic Group indicates the potential for these uncharacterized groups to contribute to nutrient cycling in lakes.
authors.affiliation: Laboratoire 'Microorganismes: Génome et Environnement', Clermont Université, Université Blaise Pascal, BP 10448, Clermont-Ferrand, F-63000, France; UMR 6023, LMGE, CNRS, Aubière, F-63171, France.
authors.forename: Mylène
authors.initials: M
authors.lastname: Hugoni
authors.forename: Isabelle
authors.initials: I
authors.lastname: Domaizon
authors.forename: Najwa
authors.initials: N
authors.lastname: Taib
authors.forename: Corinne
authors.initials: C
authors.lastname: Biderre-Petit
authors.forename: Hélène
authors.initials: H
authors.lastname: Agogué
authors.forename: Pierre E
authors.initials: PE
authors.lastname: Galand
authors.forename: Didier
authors.initials: D
authors.lastname: Debroas
authors.forename: Isabelle
authors.initials: I
authors.lastname: Mary
mesh_terms: D000641:Ammonia / Q000032:analysis; D001105:Archaea / Q000145:classification* / Q000235:genetics / Q000254:growth & development*; D058448:Biota; D019641:DNA, Archaeal / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D020869:Gene Expression Profiling; D060106:Lakes / Q000382:microbiology*; D058465:Nitrification; D010088:Oxidoreductases / Q000235:genetics; D010100:Oxygen / Q000032:analysis; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D062211:Spatio-Temporal Analysis; D014867:Water / Q000737:chemistry
chemical_list: D019641:DNA, Archaeal; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D014867:Water; D000641:Ammonia; D010088:Oxidoreductases; C045582:ammonia monooxygenase; D010100:Oxygen