Fusarium oxysporum grown on natural media was believed not to produce mycotoxins of the trichothecene family. Using a defined chemical medium toxin production was investigated for and it was found that trichothecenes were produced. A yeast bioassay using Kluyveromyces fragilis, an organiam sensitive to such trichothecenes as T-2 toxin and verrucarin, was used for detection of toxin in culture filtrates. Detectable levels of toxin (0.2 $ mu$g in litre of culture) were seen by day 4 and peaked around day 9 corresponding to maximum growth (measured by mycelial mass). After this time fluctuations in the level of toxin and growth became evident, suggesting a breakdown of the toxins by the organism for a carbon source. Search for an enzyme or enzyme system, capable of degrading T-2 toxin in snail gut enzyme digested F. oxysporum, was attempted using the esterase substrate para-nitrophenol acetate. Esterase activity was detected in all fractions including culture filtrate, soluble protein fraction and insoluble protein fraction, as well as solubilized insoluble proteins (digested by contents of the crude extract). The soluble protein fraction exhibited the highest level of activity. Cells digested with the detergent Lubrol followed by precipitation of the solubilized proteins with ammonium sulphate revealed the presence of an active component(s) in the high molecular weight portion of the soluble cell fraction collected at 50 and 75% saturation. Further purification by DEAE-sepharose failed to produce an active component.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.69524 |
| Date | January 1993 |
| Creators | Kearvell, Joan |
| Contributors | Ingram, J. M. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Microbiology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001338488, proquestno: AAIMM87819, Theses scanned by UMI/ProQuest. |
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