LE3 .A278 2021

2021

Walker, Allison
Benjamin, Jeremy

Acadia University

Bachelor of Science

Honours

Biology

Biology

Eicosapentaenoic acid (EPA) and arachidonic acid (ARA) are polyunsaturated fatty acids with important health impacts, commonly obtained from fish oil and other animal products. Oils of marine organisms occupying lower trophic levels are promising alternative sources of EPA, as they can be rich in omega-3 fatty acids and have the potential to be cultivated efficiently and sustainably. While some oomycetes are reported to produce EPA and ARA, many species such as Pythium oopapillum have not been investigated for their fatty acid production. There is also a lack of research on lipid production by marine fungi. In this study, the fatty acid profiles of ten Pythium and Phytophthora oomycete strains collected in Nova Scotia and Italy were screened, along with those of 104 marine fungal and oomycete strains collected in Japan, Italy, and Costa Rica. Strains were grown for 7 days at 20-25°C, 200 rpm before biomass was harvested and fatty acid methyl esters (FAMEs) analysis was conducted using gas-liquid chromatography. Of the 104 novel marine fungal and oomycete strains screened, only one oomycete (Phytophthora inundata) produced EPA, while some strains produced ARA in small quantities. P. oopapillum proved the most promising oomycete strain, and growth conditions were optimized to increase its EPA yield. A Plackett-Burman design was used to test the effects of ten media ingredients. Yeast extract had a significantly positive effect on the strain’s EPA yield, while a high initial glucose level had a negative effect. Temperature had the largest impact on EPA yield; P. oopapillum produced the highest yield (134.63mg/L) grown for 4 days at 25°C followed by 3 days at 15°C. This temperature shift likely balanced biomass growth rate and unsaturated fatty acid production. Removal of MgSO4 • 7H2O increased P. oopapillum’s EPA yield from 92 to 106 mg/L when grown at 25°C for 7 days, due to an increase in total fatty acid content. Further optimization of growth conditions is needed to determine whether this oomycete is suitable for commercial fatty acid production; factors such as pH, dissolved oxygen, and media supplementation with other ingredients should be investigated.

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https://scholar.acadiau.ca/islandora/object/theses:3605