Application of molecular biological techniques to a seasonal study of ammonia oxidation in a eutrophic freshwater lake
- Univ. of Liverpool (United Kingdom). School of Biological Sciences
- Windermere Labs., Far Sawrey (United Kingdom). Inst. of Freshwater Ecology
The autotrophic ammonia-oxidizing bacteria in a eutrophic freshwater lake were studied over a 12-month period. Numbers of ammonia oxidizers in the lakewater were small throughout the year, and tangential-flow concentration was required to obtain meaningful estimates of most probable numbers. Sediments from littoral and profundal sites supported comparatively large populations of these bacteria, and the nitrification potential was high, particularly in summer samples from the littoral sediment surface. In enrichment cultures, lakewater samples nitrified at low ammonium concentrations only whereas sediment samples exhibited nitrification at high ammonium concentrations also. Enrichments at low ammonium concentration did not nitrify when inoculated into high-ammonium medium, but the converse was not true. This suggests that the water column contains a population of ammonia oxidizers that is sensitive to high ammonium concentrations. The observation of nitrification at high ammonium concentration by isolates from some winter lakewater samples, identified as nitrosospiras by 16S rRNA probing, is consistent with the hypothesis that sediment ammonia oxidizers enter the water column at overturn. With only one exception, nested PCR amplification enabled the detection of Nitrosospira 16S rDNA in all samples, but Nitrosomonas (N. europaea-eutropha lineage) 16S rDNA was never obtained.
- OSTI ID:
- 675505
- Journal Information:
- Applied and Environmental Microbiology, Vol. 64, Issue 10; Other Information: PBD: Oct 1998
- Country of Publication:
- United States
- Language:
- English
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