Abstract

Marine microalga Isochrysis sp. contains omega-3 fatty acids like eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Environmental factors play a major role in PUFA biosynthesis. Hence, the study focused to optimize factors such as temperature, pH, and photoperiod by response surface methodology (RSM). RSM results showed that the model is significant (p ≤ 0.05) with a high correlation coefficient (R² = 0.908). The optimum conditions showed that maximum biomass (327 mg/L) at the temperature of 30 °C, pH of 7.5 and 16:8 (Light: Dark cycle), whereas the higher amount of DHA (13.3%) and EPA (9.0%) was observed in the conditions of 18 °C, pH of 7.5 and 16:8 (Light: Dark cycle). The biomass content was directly proportional to the temperature whereas DHA content was inversely proportional. It was revealed that the mRNA expression of EPA and DHA specific desaturases (5Des & 4Des) were significantly elevated in low temperature (20 °C) conditions. The results were highly correlated with the fatty acid profile of Isochrysis sp. grown under low temperature (20 °C) conditions which enhanced the EPA and DHA levels. This study suggests that the temperature is the most influencing factor which can be exploited in the industrial application of DHA and EPA production from Isochrysis sp.

摘要

海洋微藻等鞭金藻属。含有 omega-3 脂肪酸，如二十碳五烯酸 (EPA) 和二十二碳六烯酸 (DHA)。环境因素在 PUFA 生物合成中起主要作用。因此，该研究的重点是通过响应面方法 (RSM) 优化温度、pH 和光周期等因素。RSM 结果表明，该模型显着（p  ≤ 0.05），相关系数高（R ²= 0.908）。最佳条件表明，在 30 °C、pH 7.5 和 16:8（光：暗循环）下生物量最大（327 mg/L），而较高的 DHA（13.3%）和 EPA（9.0%） ) 在 18 °C、pH 7.5 和 16:8（光：暗循环）的条件下观察到。生物质含量与温度成正比，而 DHA 含量成反比。结果表明，在低温 (20 °C) 条件下，EPA 和 DHA 特异性去饱和酶 ( 5Des & 4Des )的 mRNA 表达显着升高。结果与等鞭金藻的脂肪酸谱高度相关sp. 在低温 (20 °C) 条件下生长，可提高 EPA 和 DHA 水平。该研究表明，温度是等鞭金藻属植物 DHA 和 EPA 生产工业应用中可利用的最大影响因素。