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dc.contributor.advisorPrinsep, Michèle R.
dc.contributor.advisorHamilton, David P.
dc.contributor.authorRogers, Shelley
dc.date.accessioned2014-08-08T04:38:29Z
dc.date.available2014-08-08T04:38:29Z
dc.date.issued2014
dc.identifier.citationRogers, S. (2014). Investigation of Microcystin Processing, Production and Export by Microcystis sp. (Thesis, Master of Science (MSc)). University of Waikato, Hamilton, New Zealand. Retrieved from https://hdl.handle.net/10289/8777en
dc.identifier.urihttps://hdl.handle.net/10289/8777
dc.description.abstractDuring this study, the effect of different processing methods on the microcystin quota (microcystins per cell) was investigated. Microcystins from two Microcystis strains and one Planktothrix strain were quantified using liquid chromatography-mass spectrometry (LC-MS) after processing via; (1) direct freezing (no prior cell concentration) and extraction by freeze-thaw cycles, (2) cell concentration by centrifugation and extraction in methanol and (3) cell concentration by filtration and extraction in methanol. Microcystin quotas were lower for samples concentrated by filtration compared with the other two methods. In order to distinguish between extracellular microcystins actively exported from cells and those that are present as a result of cell lysis, a comparative microcystin export (CME) assay was developed using LC-MS to compare the proportion of extracellular microcystins with the proportion of extracellular non-ribosomal peptide which does not get actively exported. A culture-based experiment using the CME assay demonstrated the utility of this method and indicated that export from one of the Microcystis strains had occurred. With further validation experiments, the CME assay has the potential to be a valuable new tool for determining the occurrence of microcystin export. An in situ experiment was carried out in Lake Rotorua, Kaikoura, New Zealand, using mesocosms to study the effect of Microcystis sp. cell density on microcystin production, while measuring a wide array of abiotic parameters (temperature, light intensity, pH, dissolved oxygen and nutrients). Lake water was added to ‘control’ mesocosms in which cells were concentrated to different levels and added to ‘medium cell addition’ and ‘high cell addition’ mesocosms. The microcystin quota remained relatively constant throughout the study, despite induced changes in cell density and associated environmental parameters. These results indicate that cell density is not the only factor responsible for increased microcystin synthesis and that further investigation into the effect of stress inducing abiotic parameters such as pH and dissolved oxygen concentration may be required.
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.publisherUniversity of Waikato
dc.rightsAll items in Research Commons are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectmicrocystin
dc.subjectlake
dc.subjectexport
dc.subjectCyanobacteria
dc.subjectMicrocystis
dc.subjectassay
dc.titleInvestigation of Microcystin Processing, Production and Export by Microcystis sp.
dc.typeThesis
thesis.degree.grantorUniversity of Waikato
thesis.degree.levelMasters
thesis.degree.nameMaster of Science (MSc)
dc.date.updated2014-03-03T03:08:44Z
pubs.place-of-publicationHamilton, New Zealanden_NZ


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