Abstract
Eicosapentaenoic acid (EPA) is an essential polyunsaturated fatty acid for human beings. At present, the production of commercially available long-chain polyunsaturated fatty acids, mainly from wild-caught ocean fish, is struggling to meet the increasing demand for EPA. Production of EPA by microorganisms may be an alternative, effective and economical method. The oleaginous fungus Pythium splendens RBB-5 is a potential source of EPA, and thanks to the simple culture conditions required, high yields can be achieved in a facile manner. In the study, lipid metabolomics was performed in an attempt to enhance EPA biosynthesis in Pythium splendens. Synthetic, metabolic regulation and gene expression analyses were conducted to clarify the mechanism of EPA biosynthesis, and guide optimization of EPA production. The results showed that the Δ6 desaturase pathway is the main EPA biosynthetic route in this organism, and ∆6, ∆12 and Δ17 desaturases are the rate-limiting enzymes. All the three desaturase genes were separately introduced into the parent strain to increase the flow of fatty acids into the Δ6 desaturase pathway. Enhanced expression of these key enzymes, in combination with improved regulation of metabolism, resulted in a maximum yield of 1.43 g/L in the D12 transgenic strain, which represents a tenfold increase over the parent strain before optimization. This is the higher EPA production yield yet reported for a microbial system. Our findings may allow the production of EPA at an industrial scale, and the strategy employed could be used to increase the production of EPA or other lipids in oleaginous microorganisms.
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Acknowledgements
This research was supported by the National Natural Science Foundation of China (Grant No. 20976065). We thank Mrs. Hong Cheng and Mrs. **aoman Gu of the Analysis and Testing Center of Huazhong University of Science and Technology for GC–MS.
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Ren, L., Zhou, P., Zhu, Y. et al. Improved eicosapentaenoic acid production in Pythium splendens RBB-5 based on metabolic regulation analysis. Appl Microbiol Biotechnol 101, 3769–3780 (2017). https://doi.org/10.1007/s00253-016-8044-0
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DOI: https://doi.org/10.1007/s00253-016-8044-0