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Title: Ecophysiological studies of soil ammonia oxidising bacteria
Author: Williams, David
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2009
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Chemolithotrophic oxidation of ammonia to nitrate via nitrite (autotrophic nitrification) is a key link in the cycling of nitrogen in the biosphere.  It is facilitated by diverse communities of microorganisms including the autotrophic ammonia oxidising bacteria (AOB).  A good understanding of niche differentiation among members of such communities will aid in the prediction of how a community structure and function may respond to environmental change. The work presented here aims to extend the available ecophysiological data on soil AOB with an emphasis on comparative observations between organisms under the same conditions.  Under a set of standardised conditions, several potentially ecologically relevant traits were quantified and comparisons were made between organisms in the context of their phylogenetic relationships.  Nitrosomonas europaea ATCC 19718, Nitrosomonas europaea ATCC 25978, Nitrosospira ‘Apple Valley’, Nitrosospira briensis C-128, Nitrosospira multiformis ATCC 25196, Nitrosospira tenuis NV-12, and Nitrosospira 40KI in pure culture were examined. Specific growth rates in batch culture, maximum velocities, Michaelis constants and specific oxidation velocities of ammonia oxidation, AMO transcript decay half-life and transcriptional and metabolic response to re-supply of ammonia following energy starvation were quantified.  Significant phenotypic diversity was observed and hypotheses were tested with respect to trade-offs in niche adaptation and the influence of phylogeny.  It is hoped these new data will aid in the formation and testing of further ecological and evolutionary hypotheses and will contribute to the long term goal of developing predictive models for biogeochemical cycling.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Microbial ecology ; Soil microbiology