(626c) Microbial Production of Docosahexaenoic Acid by Marine Fungi: How to Convert Glucose to Lipid Effectively

DHA(Docosahexaenoic acid, 22:6¢^{4.7.10.13.16.19})is an important kind of ɷ-3 polyunsaturated fatty acid (PUFAs). As the necessary component of cell membranes, DHA, known as “Brain Gold”, is regarded to be essential for the development of visual and neurological development of infants. In addition, it also could reduce or inhibit risk factors involved in various diseases like cardiovascular diseases. So, it is widely used in food and medical industry recently. The traditional source of DHA is fish oil, but the quality of the fish oil is variable and depends on fish species, season and location of catching sites. In addition to the high content of EPA and cholesterol, the application of fish oil in food and pharmaceutical industries was limited severely. Therefore, microbial production of DHA is the inevitable choice to ensure current DHA usage. This presentation will introduce the research results involving how to convert glucose to lipid effectively by marine fungi, Schizochytrium sp. in our group.

High cell density is the premise of the high yield of intracellular products, so the first research objective is about how to improve cell growth rate and cell yield coefficient. As we know, cell growth need abundant nutrition but lipid accumulation only happened in the nutrition limitation or environmental stress conditions. So the second part will concern this contradiction and investigated the metabolic mechanism of Schizochytrium sp. in response to nutrition limitation and environmental stress, aiming at obtaining lipids as much as possible. Thirdly, high DHA percentage in total fatty acids is the premise for high oil quality, which concerning the supply of reducing power, NADPH. A regulation strategy of adding specific activators at different fermentation stages to reinforce NADPH supply was proposed by tracking the changes of cell growth, DHA accumulation and key enzymes for NADPH synthesis during the fermentation stages. Finally, based on the above research, the results were applied to the amplification process in the industry, which will lay the foundation for the realization the goal of "high yield ", "high quality "and "stable production" of DHA bio-refining process, at the same time support the reference of methodology for other PUFAs production.