Large summertime proliferations (or blooms) of the noxious filamentous cyanobacterium Lyngbya majuscula have been observed in the coastal marine waters of Moreton Bay, Queensland. This photosynthetic organism is believed to have a high iron requirement and preliminary studies have shown that the presence of organically complexed iron stimulates growth. Since there is no evidence that Lyngbya produces siderophores to aid iron acquisition, it has been hypothesized that this organism may acquire iron via reduction of ferric complexes to the typically more labile, ferrous form. Both the phylogenetic diversity of the genus Lyngbya and the iron metabolism of L. majuscula are examined in this thesis. Software was developed to assist in the design of peR primers that targeted l6S rRNA, rpoB and Highly Iterated Palindrome (HIP) genetic structures and the subsequent phylogenetic analysis. The mechanism of iron acquisition by L. majuscula and the influence of organic complexation of iron were investigated using radioisotope and chemiluminescence-based techniques. Molecular techniques were also used to investigate the genetics of iron metabolism of L. majuscula. Results of the l6S rRNA analysis indicate that the morpho-genus Lyngbya encompasses a large genetic diversity within the cyanobacteria that is consistent with its reported metabolic and ecological diversity. Five discrete lineages comprised of organisms that fit the morophological definition of Lyngbya were discovered in this analysis. L. majuscula utilises endogenously-produced superoxide as a reductant of ferric complexes to produce the more labile ferrous forms. The nature of the organic complexes has been shown to determine the efficacy of this mechanism. A model of iron acquisition by these reductive processes was developed and was shown to generally describe all known methods of reduction-mediated iron acqUIsItIOn. Finally, the genetics of iron metabolism of L. majuscula was found to be consistent with the mechanism we propose, including the discovery of a component of a ferrous iron uptake mechanism.
| Identifer | oai:union.ndltd.org:ADTP/258366 |
| Date | January 2007 |
| Creators | Salmon, Timothy Peter, Civil & Environmental Engineering, Faculty of Engineering, UNSW |
| Publisher | Publisher:University of New South Wales. Civil & Environmental Engineering |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://unsworks.unsw.edu.au/copyright, http://unsworks.unsw.edu.au/copyright |
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