This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Jordan, F. L. Articles by Stein, L. Y. Search for Related Content PubMed PubMed Citation Articles by Jordan, F. L. Articles by Stein, L. Y. Agricola Articles by Jordan, F. L. Articles by Stein, L. Y.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, January 2005, p. 197-206, Vol. 71, No. 1
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.1.197-206.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Autotrophic Ammonia-Oxidizing Bacteria Contribute Minimally to Nitrification in a Nitrogen-Impacted Forested Ecosystem

Fiona L. Jordan,^1, J. Jason L. Cantera,¹ Mark E. Fenn,² and Lisa Y. Stein^1*

Department of Environmental Sciences, University of California, Riverside,¹ Forest Fire Laboratory, Pacific Southwest Research Station, USDA Forest Service, Riverside, California²

Received 5 February 2004/ Accepted 10 August 2004

Deposition rates of atmospheric nitrogenous pollutants to forests in the San Bernardino Mountains range east of Los Angeles, California, are the highest reported in North America. Acidic soils from the west end of the range are N-saturated and have elevated rates of N-mineralization, nitrification, and nitrate leaching. We assessed the impact of this heavy nitrogen load on autotrophic ammonia-oxidizing communities by investigating their composition, abundance, and activity. Analysis of 177 cloned ß-Proteobacteria ammonia oxidizer 16S rRNA genes from highly to moderately N-impacted soils revealed similar levels of species composition; all of the soils supported the previously characterized Nitrosospira clusters 2, 3, and 4. Ammonia oxidizer abundance measured by quantitative PCR was also similar among the soils. However, rates of potential nitrification activity were greater for N-saturated soils than for soils collected from a less impacted site, but autotrophic (i.e., acetylene-sensitive) activity was low in all soils examined. N-saturated soils incubated for 30 days with ammonium accumulated additional soluble ammonium, whereas less-N-impacted soils had a net loss of ammonium. Lastly, nitrite production by cultivated Nitrosospira multiformis, an autotrophic ammonia-oxidizing bacterium adapted to relatively high ammonium concentrations, was significantly inhibited in pH-controlled slurries of sterilized soils amended with ammonium despite the maintenance of optimal ammonia-oxidizing conditions. Together, these results showed that factors other than autotrophic ammonia oxidizers contributed to high nitrification rates in these N-impacted forest soils and, unlike many other environments, differences in nitrogen content and soil pH did not favor particular autotrophic ammonia oxidizer groups.

Present address: Environmental Research Laboratory, Department of Soil, Water and Environmental Sciences, University of Arizona, Tucson, AZ 85706.

This article has been cited by other articles:

• Watrud, L. S., Martin, K., Donegan, K. K., Stone, J. K., Coleman, C. G. (2006). Comparison of taxonomic, colony morphotype and PCR-RFLP methods to characterize microfungal diversity.. Mycologia 98: 384-392 [Abstract] [Full Text]