An investigation of the ecology and bioactive compounds of Pittosporum angustifolium endophytes

Thompson, Michael (2014) An investigation of the ecology and bioactive compounds of Pittosporum angustifolium endophytes. Honours thesis, University of Southern Queensland. (Unpublished)


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Endophytes are microorganisms that reside in the internal tissue of living plants without causing any apparent negative effects to the host. Endophytes are known to produce bioactive compounds and are looked upon as a promising source of novel bioactive compounds. There is currently limited knowledge of Australian endophytes regarding the species diversity, ecological roles and their potential as producers of antimicrobial compounds. The plant Pittosporum angustifolium was used medicinally by Indigenous Australians to treat a variety of conditions such as eczema, coughs and colds. In this study the diversity of endophytic species, host-preference of endophytes and antimicrobial potential of the resident endophytes is investigated in P. angustifolium. During this study a total of 54 endophytes were cultured from leaf samples of seven different P. angustifolium plants. Using molecular identification methods, the ITS-rDNA and SSU-rDNA regions of fungal and bacterial endophytes respectively were sequenced and matched to species recorded in GenBank. This approach, however, could not identify all isolates to the species level. Analysing the presence/absence of identified isolates in each of the seven trees found no evidence to indicate any host-specific relationships. Screening of each isolated endophyte against four human pathogens (Staphylococcus aureus, Serratia marcescens, Escherichia coli and Candida albicans) found two species displaying antimicrobial activity. Limitations narrowed the project to focus on one species which was identified as Pseudocercospora fuligena. P. fuligena was found to inhibit S. marcescens. Antimicrobial testing found that a crude extract of the fungal endophyte displayed bactericidal activity with a minimum bactericidal concentration of 2.5mg/ml. Bioassay-guided fractionation of the crude extract yielded five fractions. Two fractions displayed inhibition of S. marcescens both with a minimum inhibitory concentration of 125 μg/ml. The two fractions were not found to be bactericidal at any of the concentrations assayed. This study demonstrates the potential of P. angustifolium as a source of undiscovered endophytic species and antimicrobial compounds.

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Item Type: Thesis (Non-Research) (Honours)
Item Status: Live Archive
Additional Information: Bachelor of Science (Honours) thesis.
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Agricultural, Computational and Environmental Sciences (1 Jul 2013 - 5 Sep 2019)
Supervisors: Dearnaley, John
Date Deposited: 08 Aug 2014 08:09
Last Modified: 08 Dec 2014 06:29
Uncontrolled Keywords: Pittosporum angustifolium endophytes, ecology, bioactive compounds
Fields of Research (2008): 06 Biological Sciences > 0607 Plant Biology > 060702 Plant Cell and Molecular Biology
06 Biological Sciences > 0605 Microbiology > 060505 Mycology
Fields of Research (2020): 31 BIOLOGICAL SCIENCES > 3108 Plant biology > 310803 Plant cell and molecular biology
31 BIOLOGICAL SCIENCES > 3107 Microbiology > 310705 Mycology

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