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Microb Ecol. 2008 Oct;56(3):420-6. doi: 10.1007/s00248-007-9360-9. Epub 2008 Jan 19.

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

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Department of Biological Sciences, Northern Arizona University, PO Box 5640, Flagstaff, AZ 86011-5640, USA.


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.

[Indexed for MEDLINE]

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