Dietary eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may have a role in contributing to the prevention or inhibition of some malignancies. DHA, the most important polyunsaturated fatty acid (PUFA) in fish and thraustochytrid oils, is known for its anticancer activity. However, antigastric cancer activity of thraustochytrid microbial oil is still unclear. In this investigation, 45 thraustochytrid strains were screened for the production of antigastric cancer oil. Cytotoxicity of 12 thraustochytrid oils was assessed by 3-(4,5-dimethythiazol- 2-yl)-2,5-diphenyl tetrazolium bromide (MTT) on gastric cancer AGS cells. The most cytotoxic effect was related to the oil extracted from the qe-4 strain with 45% cell cytotoxicity. Therefore, the Taguchi methodology was used to optimize this bioactive microbial oil. The amounts of biomass, oil, and DHA were increased to 10.32 g/L, 3.86 g/L, and 1390 mg/L, respectively. Furthermore, the use of glycerol in low saline medium enhanced the yield of DHA. Then, the cytotoxicity of thraustochytrids oil rich in DHA or C16 (0.5 to 10 mg/mL), was assessed on AGS cells. Only the oil that was rich in DHA showed an inhibitory effect (IC50) on AGS cells (same as the standard DHA at 1.26 mg/mL). These new findings revealed that thraustochytrid derived oil rich in DHA, has an inhibitory effect on gastric cancer cells. Phylogenetic analysis showed that qe-4 is related to the genus Aurantiochytrium (AN: KR091914) as a potential candidate for the production of bioactive oil. In conclusion, these results certainly support further investigations on this bioactive microbial oil as an additive for the fortification of food and dairy products. Practical ApplicationThraustochytrid microbial oil rich in DHA, showed antigastric cancer activity comparable to that of pure DHA; indicating that this microbial bioactive omega-3 oil rich in the very important PUFA (DHA), can be applied as an additive for the fortification of food and dairy products. Also, Aurantiochytrium sp. KR091914, as a GRAS microorganism, is a good producer of this bioactive oil.
