Abundance and diversity of archaeal ammonia oxidizers in a coastal groundwater system.
Nitrification, the microbially catalyzed oxidation of ammonia to nitrate, is a key process in the nitrogen cycle. Archaea have been implicated in the first part of the nitrification pathway (oxidation of ammonia to nitrite), but the ecology and physiology of these organisms remain largely unknown. This work describes two different populations of sediment-associated ammonia-oxidizing archaea (AOA) in a coastal groundwater system in Cape Cod, MA. Sequence analysis of the ammonia monooxygenase subunit A gene (amoA) shows that one population of putative AOA inhabits the upper meter of the sediment, where they may experience frequent ventilation, with tidally driven overtopping and infiltration of bay water supplying dissolved oxygen, ammonium, and perhaps organic carbon. A genetically distinct population occurs deeper in the sediment, in a mixing zone between a nitrate- and oxygen-rich freshwater zone and a reduced, ammonium-bearing saltwater wedge. Both of these AOA populations are coincident with increases in the abundance of group I crenarchaeota 16S rRNA gene copies.
Rogers
Daniel R
DR
Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA. drrogers@fas.harvard.edu
Casciotti
Karen L
KL
D000641:Ammonia / Q000378:metabolism*; D001105:Archaea / Q000145:classification* / Q000235:genetics / Q000378:metabolism*; D019843:Archaeal Proteins / Q000235:genetics; D016000:Cluster Analysis; D019641:DNA, Archaeal / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D014644:Genetic Variation; D019015:Geologic Sediments / Q000382:microbiology*; D008404:Massachusetts; D008969:Molecular Sequence Data; D058465:Nitrification; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
D019843:Archaeal Proteins; D019641:DNA, Archaeal; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D000641:Ammonia; D010088:Oxidoreductases; C045582:ammonia monooxygenase