title: Heterotrophic Production of Omega-3 Long-Chain Polyunsaturated Fatty Acids by Trophically Converted Marine Diatom Phaeodactylum tricornutum.
abstract: We have created via metabolic engineering a heterotrophic strain of Phaeodactylum tricornutum that accumulates enhanced levels of the high value omega-3 long chain polyunsaturated fatty acid (LC-PUFAs) docosahexaenoic acid (DHA). This was achieved by generation of transgenic strains in which the Δ5-elongase from Ostreococcus tauri was co-expressed with a glucose transporter from the moss Physcomitrella patens. This double transformant has the capacity to grow in the dark in liquid medium supplemented with glucose and accumulate substantial levels of omega-3 LC-PUFAs. The effects of glucose concentrations on growth and LC-PUFA production of wild type and transformed strains cultivated in the light and dark were studied. The highest omega-3 LC-PUFAs accumulation was observed in cultures grown under mixotrophic conditions in the presence of 1% glucose (up to 32.2% of total fatty acids, TFA). Both DHA and EPA are detected at high levels in the neutral lipids of transgenic cells grown under phototrophic conditions, averaging 36.5% and 23.6% of TFA, respectively. This study demonstrates the potential for P. tricornutum to be developed as a viable commercial strain for both EPA and DHA production under mixo- and heterotrophic conditions.
authors.affiliation: Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK. mary.hamilton@rothamsted.ac.uk.
authors.forename: Mary L
authors.initials: ML
authors.lastname: Hamilton
authors.affiliation: Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK. stephen.powers@rothamsted.ac.uk.
authors.forename: Stephen
authors.initials: S
authors.lastname: Powers
authors.affiliation: Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK. johnathan.napier@rothamsted.ac.uk.
authors.forename: Johnathan A
authors.initials: JA
authors.lastname: Napier
authors.affiliation: Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK. olga.sayanova@rothamsted.ac.uk.
authors.forename: Olga
authors.initials: O
authors.lastname: Sayanova
mesh_terms: D003624:Darkness; D017377:Diatoms / Q000378:metabolism*; D004281:Docosahexaenoic Acids / Q000096:biosynthesis* / Q000302:isolation & purification; D015118:Eicosapentaenoic Acid / Q000096:biosynthesis* / Q000302:isolation & purification; D005947:Glucose / Q000737:chemistry; D052836:Heterotrophic Processes; D008027:Light; D060847:Metabolic Engineering / Q000379:methods
chemical_list: D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid; D005947:Glucose
keywords: DHA; EPA; Phaeodactylum tricornutum; heterotrophic; microalgae; omega-3 long chain polyunsaturated fatty acid