Abstract
Lipids produced from agricultural and industrial residues using oleaginous microorganisms for use as biofuels are attracting the attention of researchers due to their environmental benefits. However, low efficiencies and high costs limit their application to a certain extent. The present study is the first to use inositol as an enhancer to improve the production and accumulation of lipids during fermentation by the microalga Schizochytrium sp. SR21. The study aimed to maximize the production of lipids and docosahexaenoic acid (DHA) by optimizing the conditions of inositol addition into the fermentation medium. The corresponding key enzyme and metabolite profiles of SR21 were evaluated. The results indicated that the addition of 120 mg L−1 of inositol to the medium at 48 h improved lipid and DHA production by 13.90 and 20.82%, resulting in total concentrations of 22.86 and 8.53 g/L, respectively. Moreover, the ratio of unsaturated fatty acids (UFAs) to saturated fatty acids (SFAs) increased by 23.38% and is consistent with the results of the metabolomic analysis. The activity of enzymes (i.e., PC, G6PDH, NADPH-ME, and ACL) related to fatty acid synthesis in strain SR21 also increased significantly (43.38%, 28.68%, 37.47%, and 19.87%, respectively). Metabolomic analysis also showed that inositol promoted lipid synthesis in SR21 and significantly increased the relative proportion of UFAs by affecting the citrate cycle and SFA and UFA metabolic pathways. Thus, inositol is an ideal enhancer of lipid production and accumulation by oleaginous microorganisms.
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Funding
This work was supported by the Key Research and Development Programs (Modern Agriculture) of Jiangsu Province (grant number BE2013405, BE2017322), the Six Talent Peaks Project of Jiangsu Province (grant number 2015-NY-018), the Key Research and Development Program (Modern Agriculture) of Zhenjiang City (grant number NY2017010), the 333 High-level Talent Training Project of Jiangsu Province (2018), and the Shen Lan Young scholars program of Jiangsu University of Science and Technology (2015).
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Liu, ZX., You, S., Tang, BP. et al. Inositol as a new enhancer for improving lipid production and accumulation in Schizochytrium sp. SR21. Environ Sci Pollut Res 26, 35497–35508 (2019). https://doi.org/10.1007/s11356-019-06056-3
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DOI: https://doi.org/10.1007/s11356-019-06056-3