title: Evidence that ammonia-oxidizing archaea are more abundant than ammonia-oxidizing bacteria in semiarid soils of northern Arizona, USA.
abstract: Autotrophic ammonia-oxidizing communities, which are responsible for the rate-limiting step of nitrification in most soils, have not been studied extensively in semiarid ecosystems. Abundances of soil archaeal and bacterial amoA were measured with real-time polymerase chain reaction along an elevation gradient in northern Arizona. Archaeal amoA was the predominant form of amoA at all sites; however, ratios of archaeal to bacterial amoA ranged from 17 to more than 1,600. Although size of ammonia-oxidizing bacteria populations was correlated with precipitation, temperature, percent sand, and soil C/N, there were no significant relationships between ammonia-oxidizing archaea populations and any of the environmental parameters evaluated in this study. Our results suggest that in these soils, archaea may be the primary ammonia oxidizers, and that ammonia-oxidizing archaea and ammonia-oxidizing bacteria occupy different niches.
authors.affiliation: Department of Biological Sciences, Northern Arizona University, PO Box 5640, Flagstaff, AZ 86011-5640, USA. Karen.adair@nau.edu
authors.forename: Karen L
authors.initials: KL
authors.lastname: Adair
authors.forename: Egbert
authors.initials: E
authors.lastname: Schwartz
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D001105:Archaea / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D001130:Arizona; D001419:Bacteria / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D019641:DNA, Archaeal / Q000737:chemistry / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D003889:Desert Climate; D017753:Ecosystem; D018628:Gene Dosage; D016014:Linear Models; D015999:Multivariate Analysis; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012988:Soil Microbiology
chemical_list: D019641:DNA, Archaeal; D004269:DNA, Bacterial; D000641:Ammonia; D010088:Oxidoreductases; C045582:ammonia monooxygenase