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dc.contributor.advisorOlsen, Ragnar Ludvig
dc.contributor.authorSvenning, Jon Brage
dc.date.accessioned2021-03-15T11:06:06Z
dc.date.available2021-03-15T11:06:06Z
dc.date.issued2021-04-23
dc.description.abstractThe global demand for the long-chain omega-3 fatty acids EPA and DHA is increasing, and the traditional sources of these fatty acids, fish oils, are no longer able to sustain the demand. This shortage is mainly a result of the surging requirement of EPA and DHA as ingredients in fish feed for aquaculture, and as dietary supplements for human consumption. As a result, there is an increased interest towards lower trophic levels as novel sources of EPA and DHA in an effort to reduce the dependence on wild fish. The main producers of long-chained omega-3 fatty acids in cold oceans are the single celled diatoms, which use CO2 and sunlight to grow in the process of photosynthesis. Diatoms can be utilized as targets of a commercial mass cultivation, where CO2 from industrial processes is converted to a valuable diatom biomass. This may in turn supplement fish-derived biomass for the production of EPA and DHA. The purpose of this work was to improve the current production technology directed towards diatom mass cultivation. The first study investigated the effect of cultivation temperature on the growth and composition of fatty acids on a cold-water diatom. Temperature did not affect the content of EPA and DHA in the diatom at temperatures between 2-12 degrees C, which reduces the necessity of temperature regulation in cultivations targeted towards omega-3 fatty acids. The second study compared preservative treatments on biomass from a cold-water diatom, and showed that a moderate heat treatment reduced quality loss during storage. Heat treatment can therefore function as an inexpensive alternative to preserve diatom biomass. The final study examined to what extent cell wall disruption, choice of solvent and number of consecutive extractions affected the yield in lipid extraction from diatoms. In contrast to other commonly mass cultivated microalgae, product yield was determined by choice of solvent and number of extractions, independent of cell disruption. These findings will bring us closer to an industrial cultivation of diatom biomass, by lowering production costs and increasing product value.en_US
dc.description.doctoraltypeph.d.en_US
dc.description.popularabstractThe purpose of this work was to bring us closer to an industrial cultivation of diatoms as a source of marine fatty acids. The first study investigated the effect of cultivation temperature on the growth and composition of fatty acids on a diatom. The content of EPA and DHA was stable at temperatures between 2-12 degrees C, which reduces the necessity of temperature regulation in an industrial cultivation. The second study compared common preservative treatments on diatom biomass, and showed that heat treatment can function as an inexpensive alternative to preserve fresh diatom biomass during storage. The final study examined to what extent cell lysis, solvent choice and number of extractions affect yield in lipid extraction from diatoms. In contrast to other commonly cultivated microalgae, yield was determined by choice of solvent and number of extractions, independent of cell disruption. These findings improve cultivation technology by lowering production costs and increasing product value.en_US
dc.description.sponsorshipUiT The Arctic University of Norwayen_US
dc.identifier.isbn978-82-8266-195-9
dc.identifier.urihttps://hdl.handle.net/10037/20693
dc.language.isoengen_US
dc.publisherUiT The Arctic University of Norwayen_US
dc.publisherUiT Norges arktiske universiteten_US
dc.relation.haspart<p>Paper I: Svenning, J.B., Dalheim, L., Eilertsen, H.C. & Vasskog, T. (2019). Temperature dependent growth rate, lipid content and fatty acid composition of the marine cold-water diatom <i>Porosira glacialis</i>. <i>Algal Research, 37</i>, 11-16. Also available at <a href=https://doi.org/10.1016/j.algal.2018.10.009>https://doi.org/10.1016/j.algal.2018.10.009</a>. Accepted manuscript version available in Munin at <a href=https://hdl.handle.net/10037/16970>https://hdl.handle.net/10037/16970</a>. <p>Paper II: Dalheim, L., Svenning, J.B., Eilertsen, H.C., Vasskog, T. & Olsen, R.L. (2020). Stability of lipids during wet storage of the marine diatom <i>Porosira glacialis</i> under semi-preserved conditions at 4 and 20 °C. <i>Journal of Applied Phycology, 33</i>, 385-395. Also available in Munin at <a href=https://hdl.handle.net/10037/19889>https://hdl.handle.net/10037/19889</a>. <p>Paper III: Svenning, J.B., Dalheim, L., Vasskog, T., Matricon, L., Vang, B. & Olsen, R.L. (2020). Lipid yield from the diatom <i>Porosira glacialis</i> is determined by solvent choice and number of extractions, independent of cell disruption. <i>Scientific Reports, 10</i>, 22229. Also available in Munin at <a href=https://hdl.handle.net/10037/20106>https://hdl.handle.net/10037/20106</a>.en_US
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2021 The Author(s)
dc.subject.courseIDDOKTOR-002
dc.subjectVDP::Technology: 500::Biotechnology: 590en_US
dc.subjectVDP::Teknologi: 500::Bioteknologi: 590en_US
dc.subjectVDP::Technology: 500::Food science and technology: 600en_US
dc.subjectVDP::Teknologi: 500::Næringsmiddelteknologi: 600en_US
dc.titleTowards mass cultivation of diatoms as a source of marine lipidsen_US
dc.typeDoctoral thesisen_US
dc.typeDoktorgradsavhandlingen_US


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