Anammox (anaerobic ammonium oxidation) is an environmentally significant process with great importance for global biogeochemical cycles. This process is mediated by a unique suite of phylogenetically distinct chemolithoautotrophic bacteria which demonstrate novel physiological and metabolic characteristics. However, despite the importance of these organisms, there is still much which is poorly understood about them, specifically the diversity and distribution of these bacteria and their controlling environmental factors. Furthermore, genomic studies and observations from the field suggest that anammox bacteria may have a far greater metabolic diversity than previously thought, suggesting that the current understanding of these organisms is incomplete. This study aimed to elucidate these aspects of the ecology of anammox bacteria in estuarine and OMZ (oxygen minimum zone) environments. A clear community shift was observed in estuarine environments from Ca. Brocadia spp. dominated freshwater sites to Ca. Scalindua spp. dominated marine sites. The OMZ was dominated by Ca. Scalindua spp. though diversity within this clade was observed between organisms in the upper oxycline and those within the core of the OMZ. Microcosm experiments amended with organic substrates suggested that some anammox organisms (namely Ca. Brocadia spp., Ca. Jettenia spp. and Ca. Kuenenia spp.) may have the ability to assimilate carbon directly from organic substrates such as dimethylamine and urea. However, these data were inconclusive and further investigations are required to prove or disprove the hypothesis that anammox bacteria can utilise organic substrates. Nevertheless, this study improves the understanding of the ecology of anammox organisms in estuarine and OMZ environments, providing an unprecedented depth of data as to the diversity and distribution and unique insights into potentially novel metabolic capabilities of these organisms.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:606159 |
| Date | January 2013 |
| Creators | Williams, Simon |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/61716/ |
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