Production of Sustainable Eicosapentaenoic Acid- and Docosahexaenoic Acid- Rich Oil
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Date
2021-04
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Abstract
The purpose of this research is to develop a sustainable source of combined long chain omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Certain strains of the yeast Yarrowia lipolytica have been engineered to produce EPA1. Algae has been used commercially as a source of DHA2. It is hypothesized that combining EPA (made genetically engineered yeast) and DHA (produced by algae) will produce an oil with similar EPA to DHA ratio to that found naturally in fish oil. This oil may then be incorporated into functional food products.
Genetically engineered strains of Yarrowia lipolytica (Y8406 and Y8412) will be used to recreate the high oil and EPA production described in literature1. A growth curve has been prepared for each strain using optical density (absorbance at 600 nm) and dilution and plating on yeast extract peptone dextrose (YPD) agar. Initial fermentation will occur in flasks under aerobic conditions for 3 days, after which the cells will be transferred to a high-glucose media designed for lipid accumulation for 5 days. Once the cells have accumulated lipids, the oil will be separated using high pressure solvent extraction with hexane. The fatty acid profile of the yeast oil and a commercial algae oil will be measured using gas chromatography (GC) and compared to commercial fish oil samples. The yeast and algae oils will then be combined to form an oil that will contain both EPA and DHA. The final product will again be analyzed using GC to confirm the final fatty acid profile.
Growth curves of the yeast strains indicated maximum cell concentration after approximately three days. This will inform further fermentation conditions of 3 days initial fermentation and 5 days of lipid accumulation. Strains Y8406 and Y8412 have been shown to produce oil at 15.7% and 15.1% of their dry cell weight, respectively, and EPA at 51.2% and 55.8% of their total oil, respectively, and generally little DHA1. Commercial algae oil generally contains DHA up to 40% of total oil and little EPA2. In fish oil, the ratio of EPA to DHA ranges from 0.6 (cod liver oil) and 1.5 (menhaden oil) according to the USDA FoodData Central3. Therefore, the predicted ratio of yeast to algae oil should be between 0.45 and 1.12.
Research shows that fish oil and its component omega-3 fatty acids, EPA and DHA, provide health benefits such as reducing the risk of cardiac death and lowering inflammation4,5. The 2015-2020 Dietary Guidelines for Americans recommended consumption of 8 oz of seafood per week, providing an average of 250 mg of combined EPA and DHA4. Yet, a large portion of the population is not consuming the recommended amount of fish and these fatty acids due to high cost, dietary restrictions such as vegetarianism/veganism, concerns about high levels of mercury, general dislike, and other factors6,7. Additionally, in order for the population to meet these recommendations, the production of fish and fish oil must increase to levels which may present sustainability challenges8–10. Considering these factors, there is a need for non-fish-based EPA and DHA in a form that is bioactive and readily available to consumers. Future work following this study will incorporate the yeast and algae oil blend into a food product, assess consumer acceptability, and clinically test bioavailability of the fatty acids in a healthy cohort.
Description
Poster Division: Food, Agricultural, and Environmental Sciences (FAES): 1st Place (The Ohio State University Edward F. Hayes Graduate Research Forum)
Keywords
omega 3s, Eicosapentaenoic Acid, Biotechnology, Fermentation