Honours Theses

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Comparing the effectiveness of protein coding genes to the ITS gene as DNA barcode markers for species-level identification of Penicillium and Aspergillus fungal isolates
(University of New Brunswick, 2020) Po, Hui Ting; Gray, Christopher; Johnson, John
Penicillium and Aspergillus are important genera of fungi in the order Eurotiales that are species-rich and are found living ubiquitously. The ability to identify these fungal species allows researchers to collate and access valuable information associated with these fungi. In recent years, a molecular technique known as DNA barcoding has become a common method used for fungal identification. The internal transcribed spacer (ITS) gene was described in 2012 as the universal DNA barcode marker for fungal identifications but has limited sequence variability to identify species of Penicillium and Aspergillus. Protein coding genes; benA and calmodulin may be more effective barcode markers for identifying Penicillium and Aspergillus species, respectively, due to higher interspecific variations in the gene sequences. In the present study, we compare whether it is more effective to identify Penicillium and Aspergillus fungal isolates to the species level using protein coding genes or the ITS gene as barcode markers.
Cultivation of endophytic fungi inhabiting Abies balsamea using two techniques: a comparative study
(University of New Brunswick, 2018) Fitzherbert, Tyson; Gray, Christopher; Johnson, John
Two cultivation techniques: leaf segment cultivation and dilution-series cultivation, were compared for recovery of endophytes from needles of Abies balsamea collected in Saint John, New Brunswick, Canada. Endophytes were cultured on 2% malt extract agar and morphology of the endophytic growth was used to aid identification of distinct isolates. Endophytes were isolated from A. balsamea needles using the leaf segment cultivation method at a frequency of 13%, all replicates of two distinct isolates. Endophytes were isolated form eight of 25 prepared isolation plates for the dilution-series method. All endophytic growth from the dilution-series method was single-celled yeast species, while the endophytic growth from the leaf segment method was exclusively filamentous fungal species; thus, dichotomy was seen between the two methods of isolation.
Determination of a link between the taxonomic relationship of Canadian medicinal plants and the exhibited antibiotic activity of their crude extracts
(University of New Brunswick, 2019) Therrien, Julie K.; Gray, Christopher
Chemotaxonomy is effective in determining the expected chemical compounds found in extracts from different organisms. However, this is time-consuming and costly, as it is based on purified fractions of a chemical extract. Utilizing biological activity data of extracts and relating it to the taxonomic relationship of plants may be a more effective approach. The aim of this study was to determine if a link exists between the taxonomic relationship of plants and the exhibited antibiotic activity of their extracts. The antibiotic activity of methanolic extracts of 90 plants were evaluated against eight microorganisms. Bioactivity profiles were created and analyzed, using two separate methods. It was found that the lowest taxonomic level that correlated with the bioactivity profiles of the extracts was family.
Identification and DNA taxonomic analysis of a library of endophytic fungi
(University of New Brunswick, 2019) Stack, Ryleigh A.; Gray, Christopher; Johnson, John
Endophytes represent a largely untapped source of natural products. Despite a growing body of research, data and knowledge relating to endophyte biology and chemistry, one of the difficulties in endophyte research remains the accurate identification of endophytes. The advancements and development of molecular methods have provided researchers with tools that allow them to obtain an identification based on the endophyte’s DNA sequence, rather than its morphological and/or phenotypic characteristics. In the present study, the DNA extracted from 155 endophytes was analyzed following a DNA taxonomy methodology and compiled to give phylogenetic trees to obtain identifications based on the molecular properties of the endophytes, rather than their morphology. Of the 155 endophytes; 57 were identified to the species level, 65 to genus, 5 to class, 2 to subdivision, 10 to order, 15 to family, and 1 to subclass.
Investigation of antimicrobial activity of Canadian medicinal plant extracts
(University of New Brunswick, 2018) Dao, Khoi Thien; Gray, Christopher; Johnson, John
Methanolic extracts of seven Canadian medicinal plants were investigated for antimicrobial activity against a Gram-positive bacterium (Staphylococcus aureus), a Gram-negative bacterium (Pseudomonas aeruginosa), and a fungal organism (Candida albicans). Chamerion angustifolium extract was highly bioactive against S. aureus and P. aeruginosa; Crataegus sp. extract was moderately bioactive against S. aureus, but had a low bioactivity against C. albicans. The extract from Betula papyrifera had a low bioactive against both S. aureus and C. albicans. The active constituents of C. angustifolium, Crataegus sp., and B. papyrifera were detected via separation using two-dimensional thin layer chromatography followed by testing against S. aureus using bioautography. This is the first study to report antimicrobial activity of Crataegus sp. native to Canada and first study to find the antimicrobial constituents of C. angustifolium and B. papyrifera.
Isolation and identification of the bioactive natural product A-26771B from an endophytic Penicillium expansum isolate
(University of New Brunswick, 2020) Forgrave, Kirstyn A.; Gray, Christopher
Natural products are an important source of bioactive compounds and endophytic fungi derived from marine algae represent an under-investigated source of natural products. The objective of this research was to isolate and confirm that an extract from an endophytic Penicillium expansum contained the natural product A-26771B. The natural product was tentatively detected, using high-resolution electrospray ionization mass spectroscopy data, in a methanolic extract from the endophyte. Despite repeated rounds of high performance liquid chromatography and multiple fermentations of the endophyte, the compound was isolated in sub milligram quantities and identified using proton nuclear magnetic resonance data. However, prior to obtaining carbon nuclear magnetic resonance data that would confirm the identification of A-26771B the natural product degraded. Future work should include isolating more of the molecule A-26771B to determine the bioactivity of the molecule against Mycobacterium tuberculosis and Mycobacterium smegmatis.
Providing Endophytic Fungi with Taxonomic Classifications Using DNA Taxonomy and DNA Barcoding
(University of New Brunswick, 2023-04) Oh, Hannah; Gray, Christopher
Accurate taxonomic classifications are essential when conducting research about an organism. Over the years, the discovery of DNA sequence-based classification techniques (DNA barcoding and DNA taxonymy) have revolutionized this process. The Natural Products Research group (NPRG) has a library of fungi that is used to isolate bioactive molecules. In order for the NPRG to communicate the results of their studies, it is critical that the fungal isolates are provided with accurate taxonomic classifications. Therefore, this study provided fungal isolates from the NPRG’s fungal collection with taxonomic classifications by using DNA barcoding in conjunction with DNA taxonomy. In doing so, 300 of the NPRG’s fungal isolates were grouped into 158 taxonomic families.

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Browsing Honours Theses by Author "Gray, Christopher"

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