Antimicrobials from the fungal endophytes of Santalum lanceolatum

Wixted, Jemima (2014) Antimicrobials from the fungal endophytes of Santalum lanceolatum. Honours thesis, University of Southern Queensland. (Unpublished)

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Abstract

The emergence of drug resistance in organisms is a serious human health concern due to the subsequent reduction in treatment options. One way to combat resistance is the discovery and development of novel antimicrobial compounds with novel modes of action. Fungal endophytes live
within the tissues of plants and cause no visible symptoms of infection. Research already conducted in the field indicates that fungal endophytes are diverse, largely undiscovered and are potential key sources of novel bioactive compounds. High probability sources of bioactive endophytes include plants used for medicinal purposes. Santalum lanceolatum has been used by the Indigenous
Australian population to treat skin and upper respiratory infections, making it a prime candidate for investigation.

This study isolated 67 fungal and 4 bacterial isolates from the leaves, bark and fruit from five S. lanceolatum plants at five sites located in the Darling Downs. Histology of leaf samples showed fungal hyphae residing in the epidermal layer of the leaf, with projections into the mesophyll
layer. Nigrospora spp. accounted for 45 isolates across the five sites, indicating possible host preference. Eight fungal genera in total were identified; Aspergillus, Diaporthe, Fusarium, Nigrospora, Pestalotiopsis, Preussia, Pyronema and Xylaria. One bacteria was identified as a
Bacillus sp.

Initial antimicrobial activity was observed in 5 isolates – 2 unidentified bacteria, 2 Pyronema sp. and Xylaria grammica. X. grammica and one of the Pyronema sp. bulked sufficiently to fractionate for further antimicrobial testing. All fractions of both fungi, as well as the Pyronema crude extract, showed bacteriostatic activity to S. marcescens at varying minimum inhibitory
concentrations (MIC). The X. grammica crude extract showed bactericidal activity against S. marcescens at a MIC of 1.25mg/ml. Bacteriostatic activity towards S. aureus was
also seen in Pyronema sp. fractions S4R 4 and S4R 5-7 at MIC of 1mg/ml and 0.125mg/ml respectively. These results indicate that S. lanceolatum as found on the Darling Downs is a source of potential novel fungal endophytes which produce secondary metabolites with antimicrobial properties against clinically significant pathogens.


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Item Type: Thesis (Non-Research) (Honours)
Item Status: Live Archive
Additional Information: BBMS (Honours) thesis.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Agricultural, Computational and Environmental Sciences
Supervisors: Lynch, Mark; Dearnaley, John
Date Deposited: 23 Apr 2015 05:37
Last Modified: 23 Apr 2015 05:40
Uncontrolled Keywords: Santalum lanceolatum; fungal endophytes; antimicrobials; antimicrobial potential; medicinal purposes
Fields of Research : 06 Biological Sciences > 0605 Microbiology > 060501 Bacteriology
06 Biological Sciences > 0607 Plant Biology > 060704 Plant Pathology
03 Chemical Sciences > 0304 Medicinal and Biomolecular Chemistry > 030403 Characterisation of Biological Macromolecules
URI: http://eprints.usq.edu.au/id/eprint/27161

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