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Dietary TG DHA position impact on lymph TG DHA position. After gastro-intestinal digestion and absorption, DHA is incorporated into TG in enterocytes during re-synthesis of lipids. Neo-synthesized lipids are compacted with PL and proteins to form chylomicrons which are then exported to the lymph stream. When DHA is provided by fish oil (DHA mainly at the sn-2 position), DHA is equally distributed between the 3 positions in lymph TG. However, when DHA is supplied from a marine mammal oil (DHA exclusively at the sn-1/3 positions), its position is mainly preserved so that DHA remains at sn-1/3 position of lymph TG.
Source publication
The health benefits of a diet rich in omega-3 long chain polyunsaturated fatty acids (n-3 LC-PUFA) no longer need to be proven. However, while health authorities attempt to increase the consumption of the n-3 LC-PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), data from the latest intake surveys demonstrate that EPA and DHA consump...
Citations
Schizochytrium sp . is a heterotrophic microorganism capable of accumulating polyunsaturated fatty acids and has achieved industrial production of docosahexaenoic acid (DHA). It also has the potential for eicosapentaenoic acid (EPA) production. In this study, it was found that the cell growth, lipid synthesis and fatty acid composition of Schizochytrium sp. were significantly affected by the level of cobalamin in the medium, especially with regard to the content of EPA in the fatty acids. The content of EPA in the fatty acids increased 17.91 times, reaching 12.00%, but cell growth and lipid synthesis were significantly inhibited under cobalamin deficiency. The response mechanism for this phenomenon was revealed through combined lipidomic and transcriptomic analysis. Although cell growth was inhibited under cobalamin deficiency, the genes encoding key enzymes in central carbon metabolism were still up‐regulated to provide precursors (Acetyl‐CoA) and reducing power (NADPH) for the synthesis and accumulation of fatty acids. Moreover, the main lipid subclasses observed during cobalamin deficiency were glycerolipids (including glycerophospholipids), with EPA primarily distributed in them. The genes involved in the biosynthesis of these lipid subclasses were significantly up‐regulated, such as the key enzymes in the Kennedy pathway for the synthesis of triglycerides. Thus, this study provided insights into the specific response of Schizochytrium sp. to cobalamin deficiency and identified a subset of new genes that can be engineered for modification.
For the increasing demand for lipids and terpenoids in humans, biological fermentation has become an attractive choice due to the safety and sustainability. Thraustochytrids have been identified as promising producers of polyunsaturated fatty acids because of their high lipid content and simple fatty acid composition. In addition, thraustochytrids are also potential producers of terpenoids for their completed mevalonate pathway. Chemical regulators can be used to stimulate or inhibit metabolic pathways, which are equivalent to effects of overexpression and suppression approaches. The application of chemical regulators is potentially an easy and practical approach to improve the lipid and terpenoid yield in thraustochytrids, which has become a research focus. In this review, the mechanisms of chemical regulators promoting lipid and terpenoid biosynthesis in thraustochytrids are elucidated. Various chemical regulators which can directly enhance the biosynthesis of lipids and terpenoids are summarized depending on the type of chemicals. In addition, some chemical regulators are demonstrated to indirectly improve lipid and terpenoid yield by reducing the conversion of metabolites and reducing oxidative stress. Therefore, the addition of chemical regulators can be a useful alternative strategy for improving lipid and terpenoid accumulation in large-scale cultivation of thraustochytrids.
The fermentation production of docosahexaenoic acid (DHA) is an industrial process with huge consumption of freshwater resource and nutrient, such as carbon sources and nitrogen sources. In this study, seawater and fermentation wastewater were introduced into the fermentation production of DHA, which could solve the problem of fermentation industry competing with humans for freshwater. In addition, a green fermentation strategy with pH control using waste ammonia, NaOH and citric acid as well as FW recycling was proposed. It could provide a stable external environment for cell growth and lipid synthesis while alleviating the dependence on organic nitrogen sources of Schizochytrium sp. It was proved that this strategy has good industrialization potential for DHA production, and the biomass, lipid and DHA yield reached to 195.8 g/L, 74.4 g/L and 46.4 g/L in 50 L bioreactor, respectively. This study provides a green and economic bioprocess technology for DHA production by Schizochytrium sp.
