Characteristics of Valuable Fatty Acid Production by Novel Strains of Aurantiochytrium sp

Aurantiochytrium spp. have received increasing interest because of their high productivity of polyunsaturated fatty acids, particularly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), and odd-chain fatty acids (OCFAs) such as pentadecanoic acid (PA) and heptadecanoic acid (HA). In this study, three novel strains of Aurantiochytrium sp. (strains 9LR, 10W, and 10LW) were cultured in various conditions of temperature, salinity, and pH. The three strains grew and produced DHA and EPA at a wide range of temperature (10–35°C), salinity (5–80 practical salinity units [PSU]), and initial culture pH (3–9). They demonstrated their highest biomass, DHA, and EPA production at 25°C, while production decreased at more extreme temperatures. Salinity of 20–35 PSU and pH 5–8 were most favorable for growth and DHA and EPA production. The DHA/EPA ratio of strain 9LR was highest at 10°C, reflecting a differential response of DHA and EPA production to cold. pH and salinity did not significantly affect the DHA/EPA ratio. PA and HA production by the three strains was optimal at 25°C, 30 PSU, and pH 7. None of the strains produced OCFAs at 10°C. Our findings emphasize the importance of the environmental conditions for Aurantiochytrium sp. growth and fatty acid composition. Because of the tolerance of these Aurantiochytrium sp. strains to wide ranges of pH and salinity, various liquid wastes may be used to culture the strains to produce valuable fatty acids, even in extreme conditions.