title: Nitrification in terrestrial hot springs of Iceland and Kamchatka.
abstract: Archaea have been detected recently as a major and often dominant component of the microbial communities performing ammonia oxidation in terrestrial and marine environments. In a molecular survey of archaeal ammonia monooxygenase (AMO) genes in terrestrial hot springs of Iceland and Kamchatka, the amoA gene encoding the alpha-subunit of AMO was detected in a total of 14 hot springs out of the 22 investigated. Most of these amoA-positive hot springs had temperatures between 82 and 97 degrees C and pH range between 2.5 and 7. In phylogenetic analyses, these amoA genes formed three independent lineages within the known sequence clusters of marine or soil origin. Furthermore, in situ gross nitrification rates in Icelandic hot springs were estimated by the pool dilution technique directly on site. At temperatures above 80 degrees C, between 56 and 159 mumol NO(3)(-) L(-1) mud per day was produced. Furthermore, addition of ammonium to the hot spring samples before incubation yielded a more than twofold higher potential nitrification rate, indicating that the process was limited by ammonia supply. Our data provide evidence for an active role of archaea in nitrification of hot springs in a wide range of pH values and at a high temperature.
authors: Department of Biology, Center for Geobiology, University of Bergen, Bergen, Norway.
authors: Laila J
authors: LJ
authors: Reigstad
authors: Andreas
authors: A
authors: Richter
authors: Holger
authors: H
authors: Daims
authors: Tim
authors: T
authors: Urich
authors: Lorenz
authors: L
authors: Schwark
authors: Christa
authors: C
authors: Schleper
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D001105:Archaea / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D019843:Archaeal Proteins / Q000235:genetics; D016000:Cluster Analysis; D019641:DNA, Archaeal / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D045482:Hot Springs / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D007055:Iceland; D008969:Molecular Sequence Data; D009566:Nitrates / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012426:Russia; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D013696:Temperature
chemical_list: D019843:Archaeal Proteins; D019641:DNA, Archaeal; D009566:Nitrates; D000641:Ammonia; D010088:Oxidoreductases; C045582:ammonia monooxygenase