Production of squalene and fatty acids by Thraustochytrium sp. RT2316-16: effects of dissolved oxygen and the medium composition.

Abstract

Thraustochytrium sp. RT2316-16 is a versatile marine microbe that produces useful compounds including docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), carotenoids and coenzyme Q₁₀. Unlike the other reported Thraustochytrium spp., RT2316-16 is psychrophilic. This report identifies RT2316-16 as a potential source of squalene and assesses squalene accumulation in the biomass under different culture conditions. Furthermore, the effects of dissolved oxygen (DO) concentration on the production of fatty acids are reported for the first time. The squalene content of the biomass depended on the composition of the culture medium and the DO concentration. The accumulation of squalene was promoted when the mass ratio of glucose (or glycerol) relative to organic nitrogen was high and the DO concentration was 20% of air saturation. The highest concentration of squalene in the medium containing glucose was 1.49 ± 0.06 g L^-1, whereas it was 0.91 ± 0.05 g L^-1 in the medium containing glycerol. Relatively high concentrations of EPA (224 ± 12 mg L^-1) and DHA (550 ± 25 mg L^-1) could be obtained in glucose-containing media with a DO concentration of 20%. A fed-batch operation was found to be suitable for enhancing the concentrations of EPA and DHA. Culture conditions for enhanced production of EPA, DHA and squalene by RT2316-16 are reported. Compared to other thraustochytrids, RT2316-16 was shown to be an excellent producer of squalene.