Evidence that ammonia-oxidizing archaea are more abundant than ammonia-oxidizing bacteria in semiarid soils of northern Arizona, USA

Karen L. Adair, Egbert Schwartz

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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.

Original languageEnglish (US)
Pages (from-to)420-426
Number of pages7
JournalMicrobial Ecology
Issue number3
StatePublished - Oct 1 2008


ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Soil Science

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