Polyunsaturated Fatty Acid Production by a Marine Protist, Thraustochytrium

Marine protists have recently received much research interest as biomanufacturers to produce biofuels (e.g., lipid for biodiesel) and high value bioproducts [e.g., docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), astaxanthin, β-carotene and Vitamin Bs].  Thraustochytrium striatum is a promising species for polyunsaturated fatty acid production (PUFA). It could accumulate up to 80% total lipid (dry basis) with more than 25% DHA content. However, it did not receive much research on optimization of cultivations for PUFA production. Focusing on the strain, T. striatum ATCC 24473, this research will characterize and optimize the cultivation conditions to achieve maximum biomass concentration and total lipid and PUFA yield in terms of glucose and yeast /peptone concentrations, salinity and operation conditions (pH, temperature, and shaking speed).  To reduce the substrate cost, other carbon (xylose, sucrose, acetic acid, glycerol and starch) and nitrogen (monosodium glutamate, ammonium chloride, urea and sodium nitrate) sources will be also investigated to support the growth of T. striatum in addition to glucose and yeast extract/peptone. Our preliminary test found T. striatum can produce extracellular enzymes such as cellulase and xylanase. Therefore, lignocellulosic biomass (dilute acid pretreated switchgrass) will be also tested as a carbon source which would significantly reduce the production cost and enhance the process sustainability. The results of this research will be useful to develop new lines of microorganisms to produce affordable and renewable bioproducts and biofuels.

Keywords: Polyunsaturated fatty acids, marine protist, Thraustochytrium Striatum, biofuel, bioproduct