Schizochytrium sp. is considered as a promising alternative commercial source of docosahexaenoic acid (DHA), but the production is hindered by the high feedstock cost. In this study, inulin is used as a cheap and readily available feedstock for Schizochytrium sp. ATCC 20888 to produce DHA. The strain could not utilize inulin directly and therefore inulin first needed to be hydrolyzed. Compared with the acidic hydrolyzate by HCl and hydrolyzate by endo‐inulinase, the hydrolyzate by exo‐inulinase serves as the most effective carbon source for microalgal growth. Hydrolysis of inulin by exo‐inulinase is further optimized, and up to 97.8% of inulin conversion is obtained under the optimal conditions of 40 °C, pH 7.0, substrate concentration of 80 g L⁻¹ and exo‐inulinase loading of 2 g kg⁻¹ substrate for 12 h. The resulting hydrolyzate containing mainly fructose is used for the DHA production by the microalga. The lipid content in biomass, DHA content in total fatty acids, DHA yield, and DHA productivity at 72 h reach 45.26%, 35.59%, 5.64 g L⁻¹ and 1.88 g L⁻¹ d⁻¹, respectively. The results suggest that inulin is an excellent feedstock for Schizochytrium sp. suitable for commercial DHA production.

中文翻译：

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菊粉作为裂殖壶菌属生产二十二碳六烯酸的有希望的替代原料。ATCC 20888

裂殖藻 被认为是二十二碳六烯酸（DHA）的有前途的替代商业来源，但生产受到高原料成本的阻碍。在这项研究中，菊粉被用作裂殖壶菌属的廉价廉价原料。ATCC 20888生产DHA。该菌株不能直接利用菊粉，因此首先需要将菊粉水解。与盐酸的酸性水解产物和菊糖内切酶水解产物相比，外菊糖酶的水解产物是微藻生长最有效的碳源。进一步优化了外泌菊粉酶对菊粉的水解，在40°C，pH 7.0，底物浓度80 g L ^-1的最佳条件下，菊粉转化率高达97.8％。以及2 g kg ^-1底物的外菊糖酶负载量为12 h。所得的主要包含果糖的水解产物被微藻用于生产DHA。72小时时生物质中的脂质含量，总脂肪酸中的DHA含量，DHA产率和DHA生产率分别达到45.26％，35.59％，5.64g L ^-1和1.88g L ^-1 d ^-1。结果表明菊粉是Schizochytrium sp的优良原料。适用于商业DHA生产。