title: Metabolic engineering of lipid catabolism increases microalgal lipid accumulation without compromising growth.
abstract: Biologically derived fuels are viable alternatives to traditional fossil fuels, and microalgae are a particularly promising source, but improvements are required throughout the production process to increase productivity and reduce cost. Metabolic engineering to increase yields of biofuel-relevant lipids in these organisms without compromising growth is an important aspect of advancing economic feasibility. We report that the targeted knockdown of a multifunctional lipase/phospholipase/acyltransferase increased lipid yields without affecting growth in the diatom Thalassiosira pseudonana. Antisense-expressing knockdown strains 1A6 and 1B1 exhibited wild-type-like growth and increased lipid content under both continuous light and alternating light/dark conditions. Strains 1A6 and 1B1, respectively, contained 2.4- and 3.3-fold higher lipid content than wild-type during exponential growth, and 4.1- and 3.2-fold higher lipid content than wild-type after 40 h of silicon starvation. Analyses of fatty acids, lipid classes, and membrane stability in the transgenic strains suggest a role for this enzyme in membrane lipid turnover and lipid homeostasis. These results demonstrate that targeted metabolic manipulations can be used to increase lipid accumulation in eukaryotic microalgae without compromising growth.
authors.affiliation: Scripps Institution of Oceanography, and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093.
authors.forename: Emily M
authors.initials: EM
authors.lastname: Trentacoste
authors.forename: Roshan P
authors.initials: RP
authors.lastname: Shrestha
authors.forename: Sarah R
authors.initials: SR
authors.lastname: Smith
authors.forename: Corine
authors.initials: C
authors.lastname: Glé
authors.forename: Aaron C
authors.initials: AC
authors.lastname: Hartmann
authors.forename: Mark
authors.initials: M
authors.lastname: Hildebrand
authors.forename: William H
authors.initials: WH
authors.lastname: Gerwick
mesh_terms: D056804:Biofuels; D018533:Biomass; D015153:Blotting, Western; D002855:Chromatography, Thin Layer; D017377:Diatoms / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005434:Flow Cytometry; D055785:Gene Knockdown Techniques; D050356:Lipid Metabolism / Q000502:physiology*; D060847:Metabolic Engineering / Q000379:methods*; D058086:Microalgae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D030781:Organisms, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D034622:RNA Interference
chemical_list: D056804:Biofuels
keywords: RNAi; algal biofuel; metabolism; targeted manipulation; triacylglycerol