A new subarctic strain of Tetradesmus obliquus—part I: identification and fatty acid profiling

Abstract

We isolated a new subarctic strain Tetradesmus obliquus IPPAS S-2023 (Scenedesmaceae, Chlorophyceae) from rock baths in the White Sea. To verify its taxonomic assignment, internal transcribed spacer 2 (ITS2) of the strain was sequenced and its secondary structure was compared with predicted ITS2 secondary structures of Scenedesmaceae. The analysis of the ITS2 made it possible to assign the new strain IPPAS S-2023 to the species T. obliquus. The ultrastructural studies and energy-dispersive X-ray spectroscopy (EDX) analysis revealed a marked accumulation of vacuolar inclusions enriched in phosphorus and nitrogen (N) as well as cytoplasmiс oil bodies. Most of predicted properties of biodiesel derived from the fatty acids profile of the strain grown in the N-free medium complied with the requirements of European and American standards. The results suggest that the new subarctic strain T. obliquus IPPAS S-2023 is a promising candidate for nutrients biosequestration and for biodiesel production. In a companion paper, we assess its biomass production capability and suitability and demonstrated suitability of IPPAS S-2023 as a reference strain for studies on elevated CO2 stress effects selection of carbon dioxide-tolerant microalgae by comparison with a CO2-tolerant strain IPPAS S-2014.