Thesis
Chemical profiling and biotechnological potential of marine microalgae in response to light and abiotic stress
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2022
- Thesis identifier
- T16180
- Person Identifier (Local)
- 201750125
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Microalgae form the base of the aquatic food chain and have important ecological functions, including nutrient cycling and carbon capturing. These microscopic eukaryotes are incredibly diverse, with an estimated 72,000 extant species. They have been investigated for their biotechnological potential in industries such as nutraceutical, cosmetic, and biofuel. Most research has focused on specific high-value metabolites such as astaxanthin or β-carotene for human health, or classes of natural products such as polyunsaturated fatty acids for biofuels. However, a systematicuntargeted approach to exploring the chemical diversity of microalgal metabolites has yet to be performed. Unlocking this chemical potential could provide further applications and incentives to the microalgal biotechnology sector.This thesis aims to fill this gap by exploring the chemical space of microalgae and the elicitation of further chemistry using abiotic stress. A comparative metabolomics study of 36 microalgal strains from both freshwater and marine environments showed that Haptophytes were a rich source of chemistry compared to the well-studied Chlorophytes. It also explored chemical diversity across strains of the same species, providing evidence that isolation environment rather than phylogenetic relationships could be used to group microalgae based on chemical profiles. To investigate thechemistry produced by three strains of marine microalgae, Dunaliella primolecta, Nannochloropsis oculata, and Phaeodactylum tricornutum were cultured under varying conditions of salinity, sodium chloride, nitrate, and pH and Global Natural Products Social (GNPS) molecular networking was used to gain insights into the effect of these stresses on metabolite production. A total of 2284 metabolites were detected across all strains and conditions, with 49% of those metabolites specific to cultures grown under stress conditions (i.e., not in the control). Salinity had the greatest effectwith 22.8% of metabolites only produced under salinity stress. From comparison with over 33 libraries of mass spectral data, only five metabolites were identified, stressing the need for more open-access natural product -and specifically algal natural product - databases. Finally, we partnered with Xanthella Ltd., a marine biotechnology company in Scotland, to study the effect of 405 nm light on growth of four strains of microalgae and the production of antimicrobial metabolites. This wavelength has been shown to reduce bacterial contamination in cultures but is an expensive regimen to apply at a large scale. The production of high-value metabolites under this light regimen could enable culturing under 405 nm illumination to be economically viable. Although no bioactivity was observed from extracts or fractions, molecular networking did show that 16-25% of metabolites were either exclusively produced under 405 nm illumination or absent from the white light control condition. This thesis offers a starting point for fundamental and comparative research into microalgal growth and metabolite production and their applications in human health.
- Advisor / supervisor
- Duncan, Katherine R.
- Resource Type
- DOI
- Date Created
- 2021
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PDF of thesis T16180 | 2022-03-24 | Público | Baixar |