Isolation and molecular characterization of Thraustochytrium strain isolated from Antarctic Peninsula and its biotechnological potential in the production of fatty acids

ABSTRACT Thraustochytrids are unicellular protists belonging to the Labyrinthulomycetes class, which are characterized by the presence of a high lipid content that could replace conventional fatty acids. They show a wide geographic distribution, however their diversity in the Antarctic Region is rather scarce. The analysis based on the complete sequence of 18S rRNA gene showed that strain 34-2 belongs to the species Thraustochytrium kinnei, with 99% identity. The total lipid profile shows a wide range of saturated fatty acids with abundance of palmitic acid (16:0), showing a range of 16.1-19.7%. On the other hand, long-chain polyunsaturated fatty acids, mainly docosahexaenoic acid and eicosapentaenoic acid are present in a range of 24-48% and 6.1-9.3%, respectively. All factors analyzed in cells (biomass, carbon consumption and lipid content) changed with variations of culture temperature (10 °C and 25 °C). The growth in glucose at a temperature of 10 °C presented the most favorable conditions to produce omega-3fatty acid. This research provides the identification and characterization of a Thraustochytrids strain, with a total lipid content that presents potential applications in the production of nutritional supplements and as well biofuels.

Selection of Schizochytrium limacinum mutants based on butanol tolerance

Background: Mutation breeding is one of the most important routes to achieving high docosahexaenoic acid (DHA) productivity using Schizochytrium. However, few selection strategies have been reported that aim to generate a high DHA content in Schizochytrium lipids. Results: First, culture temperature altered the butanol tolerance of Schizochytrium limacinum B4D1. Second, S. limacinum E8 was obtained by selecting mutants with high butanol tolerance. This mutant exhibited a 17.97% lower proportion of DHA than the parent strain S. limacinum B4D1. Third, a negative selection strategy was designed in which S. limacinum F6, a mutant with poor butanol tolerance, was obtained. The proportion of DHA in S. limacinum F6 was 11.22% higher than that of parent strain S. limacinum B4D1. Finally, the performances of S. limacinum B4D1, E8 and F6 were compared. These three strains had different fatty acid profiles, but there was no statistical difference in their biomasses and lipid yields. Conclusion: It was feasible to identified the relative DHA content of S. limacinum mutants based on their butanol tolerance.