二十二碳六烯酸(DHA)作为ω-3多不饱和脂肪酸(PUFA)之一,在大脑发育中起着关键作用,广泛应用于食品添加剂和制药行业。裂殖囊虫sp.通常被认为是DHA工业化的令人满意的菌株。这项研究的目的是评估磷酸甘露聚糖酰转移酶(PPTase)和ω-3脂肪酸去饱和酶(FAD)调节裂殖细胞酵母中DHA含量的可行性。PPTase对于激活聚酮类合酶(PKS)途径至关重要,可以将apo-酰基-载体蛋白(apo-ACP)转移到holo-ACP中,并在DHA合成中起关键作用。此外,DHA和二十二碳五烯酸(DPA)通过PKS途径同时合成,因此高DPA合成限制了DHA含量的增加。此外,PKS途径的详细机制尚未完全阐明,因此很难通过修改PKS来提高DHA含量。然而,ω-3FAD可以将DPA转化为DHA,提高DHA含量和降低DPA含量是最直接有效的途径。基于此,我们过表达PPTase以通过PKS途径增强DHA的合成,过表达的ω-3FAD将PKS途径的副产物转化为DHA,和共同过表达的PPTase和ω-3FAD。有了这些策略,与野生型相比,最终的脂质和DHA滴度分别为92.5g/L和51.5g/L,分别增长46.4%和78.1%。本研究建立了高效的DHA生产菌株,并为裂殖菊属的工业DHA生产提供了一些可行的策略。本文受版权保护。保留所有权利。
Docosahexaenoic acid (DHA) as one of ω-3 polyunsaturated fatty acids (PUFAs), plays a key role in brain development, and is widely used in food additives and the pharmaceutical industry. Schizochytrium sp. is often considered as a satisfactory strain for DHA industrialization. The aim of this study was to assess the feasibility of phosphopantetheinyl transferase (PPTase) and ω-3 fatty acid desaturase (FAD) for regulating DHA content in Schizochytrium sp. PPTase is essential to activate the polyketide-like synthase (PKS) pathway, which can transfer apo-acyl-carrier protein (apo-ACP) into holo-ACP, and plays a key role in DHA synthesis. Moreover, DHA and docosapentaenoic acid (DPA) are synthesized by the PKS pathway simultaneously, so high DPA synthesis limits the increase of DHA content. In addition, the detailed mechanisms of PKS pathway have not been fully elucidated, so it is difficult to improve DHA content by modifying PKS. However, ω-3 FAD can convert DPA into DHA, and it is the most direct and effective way to increase DHA content and reduce DPA content. Based on this, PPTase was overexpressed to enhance the synthesis of DHA by the PKS pathway, overexpressed ω-3 FAD to convert the co-product of the PKS pathway into DHA, and co-overexpressed PPTase and ω-3 FAD. With these strategies, compared with wild type, the final lipid, and DHA titer were 92.5 and 51.5 g L-1 , which increased by 46.4% and 78.1%, respectively. This study established an efficient DHA production strain, and provided some feasible strategies for industrial DHA production in Schizochytrium sp.