Cyanobacteria are present in most water bodies and sometimes grow to large populations known as blooms. Some of these cyanobacteria are also capable of producing toxins which can be fatal to livestock and humans. The production of cyanobacterial toxins is not specles-, but gene-specific, so the prediction of toxicity based on identification of the cyanobacteria using morphological characteristics is unlikely to be reliable. A better way to predict the likely toxicity of a bloom is the use of molecular techniques to detect the genes for toxin production and this was the approach taken in the first part of this project. This consisted of an analysis of . both cyanobacterial diversity and the occurrence of toxin genes in selected water bodies in Yorkshire. The mcyE gene, specific to some Microcystis sp. Anabaena sp. and Planktothrix sp. was found in plankton samples taken from the selected sites. The second part of the project was concerned with the use of rotting barley straw to inhibit cyanobacterial growth. Control of bloom formation using chemicals such as copper sulphate can have damaging environmental consequences but an alternative is the use of barley straw, the efficacy of which has been previously confirmed. Of the five newly-isolated cyanobacteria tested in this project, Microcystis strains 50053 and 50054, and Pseudanabaena strains 50055 and 50056 were markedly susceptible to straw inhibition, while Anabaena strain 50051 was susceptible, but to a much lesser degree. It was shown that prolonged incubation of sterile straw did not render it active at inhibiting the growth of the test cyanobacteria, conclusively demonstrating for the first time that straw activation requires microbial activity. This project was also the first to examine bacterial and fungal diversity on rotting barley straw and revealed a complex population of bacteria and fungi, many of which have the capacity for lignin degradation. This observation strengthens the evidence in support of the hypothesis that lignin derivatives released during the breakdown of straw may be responsible for inhibiting cyanobacterial growth.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:582098 |
| Date | January 2012 |
| Creators | Lalung, Japareng |
| Publisher | University of Leeds |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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