Details of Award
NERC Reference : NE/C515271/1
Are non-thermophilic soil crenarchaea ammonia oxidisers?
Grant Award
- Principal Investigator:
- Professor J Prosser, University of Aberdeen, Institute of Medical Sciences
- Grant held at:
- University of Aberdeen, Institute of Medical Sciences
- Science Area:
- Terrestrial
- Overall Classification:
- Terrestrial
- ENRIs:
- Biodiversity
- Science Topics:
- Environmental Microbiology
- Environmental Genomics
- Population Ecology
- Abstract:
- Soil contains a complex and highly diverse community of microorganisms. These microorganisms are required for soil formation and for the many biologically-mediated, nutrient cycling processes that take place within soil. These processes are essential for maintenance of soil structure and for cycling of nutrients for plant growth. The majority of soil microorganisms cannot be readily cultivated in the laboratory but, in the past decade, molecular techniques have been used to characterise soil microbial communities. Typically, molecular analysis involves extraction of soil DNA or RNA and amplification of genes that provide information on microbial identity. The most common approach involves amplification of 16S rRNA genes, which are cloned and sequenced Sequences are used for phylogenetic analysis to determine Identity and diversity of the community. Molecular analysis has revealed the existence of considerable microbial diversity in soil and the existence of many groups with no cultivated representative. Non-thermophilic Crenarchaeota exemplify this situation. They belong to the Archaea, one of the three major lineages of life, but Archaea are traditionally associated with extreme environments, e.g. low pH, high temperature. Non-thermophilic Crenarachaeota are abundant and ubiquitous in temperate soils but, because none has ever been cultivated, we have no information on their physiological characteristics. It is therefore not possible to determine their role in soil processes or their ecosystem function. Two recent studies involving sequencing of large fragments of DNA from soil and marine environments indicate a possible function for these organisms. 16S rRNA genes of non-thermophilic Crenarchaeota have been found on sections of environmental DNA that also contain genes (amoA genes) that encode the enzyme ammonia monooxygenase. This enzyme catalyses the oxidation of ammonia to nitrite, the first step in nitrification, with subsequent oxidation of nitrite to nitrate by other bacteria. Soil nitrification is important in regulating the supply of nitrogen to plants and contributes to nitrate pollution of groundwaters Cultivated ammonia oxidisers are Bacteria, rather than Archaea, and the amoA genes from the two groups form different phylogenetic groupings. The aim of this project is to determine whether non-thermophilic Crenarchaeota play a role in nitrification in the soil. Experiments will involve incubation of soil with ammonia in the presence and absence of known inhibitors of ammonia oxidation. Soil will also be amended with CO2 labelled with the stable (heavy) isotope C or with labelled organic compounds known to be converted by ammonia monooxygenase. Nucleic acids in organisms assimilating these substrates will be labelled and 13C- and 12C-labelled nucleic acids will then be separated by density gradient centrifugation. The different nucleic acid fractions will be analysed, by amplification of 1 6S rRNA genes and amoA genes, to determine which organisms assimilated the labelled compounds. In addition, mRNA extracted from soil will be analysed to determine whether the crenarchaeal amoA genes were expressed when ammonia was added and not expressed in the presence of nitrification inhibitors. The project therefore will therefore determine whether this abundant group of microorganisms contributes to an Important soil ecosystem process, soil nitrification.
- NERC Reference:
- NE/C515271/1
- Grant Stage:
- Completed
- Scheme:
- Small Grants Pre FEC
- Grant Status:
- Closed
- Programme:
- Small Grants
This grant award has a total value of £30,605
FDAB - Financial Details (Award breakdown by headings)
| Total - Staff | Total - T&S | Total - Other Costs | Total - Indirect Costs |
|---|---|---|---|
| £18,302 | £810 | £3,075 | £8,419 |
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