Rewiring the Metabolic Network to Increase Docosahexaenoic Acid Productivity in Crypthecodinium cohnii by Fermentation Supernatant-Based Adaptive Laboratory Evolution

Liangsen Liu; Jinjin Diao; Yali Bi; Lei Zeng; Fangzhong Wang; Lei Chen; Weiwen Zhang

doi:10.3389/fmicb.2022.824189

Rewiring the Metabolic Network to Increase Docosahexaenoic Acid Productivity in Crypthecodinium cohnii by Fermentation Supernatant-Based Adaptive Laboratory Evolution

Front Microbiol. 2022 Mar 2:13:824189. doi: 10.3389/fmicb.2022.824189. eCollection 2022.

Authors

Liangsen Liu^{1

2

3}, Jinjin Diao^{1

2

3}, Yali Bi^{1

2

3}, Lei Zeng^{1

2

3}, Fangzhong Wang^{1

2

4

5}, Lei Chen^{1

2

3}, Weiwen Zhang^{1

2

3

4

5}

Affiliations

¹ Laboratory of Synthetic Microbiology, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China.
² Key Laboratory of Systems Bioengineering, Ministry of Education of China, Tianjin, China.
³ Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, China.
⁴ Center for Biosafety Research and Strategy, Tianjin University, Tianjin, China.
⁵ Law School, Tianjin University, Tianjin, China.

Abstract

Docosahexaenoic acid (DHA, 22:6n-3) plays significant roles in enhancing human health and preventing human diseases. The heterotrophic marine dinoflagellate Crypthecodinium cohnii is a good candidate to produce high-quality DHA. To overcome the inhibition caused by the fermentation supernatant in the late fermentation stage of DHA-producing C. cohnii, fermentation supernatant-based adaptive laboratory evolution (FS-ALE) was conducted. The cell growth and DHA productivity of the evolved strain (FS280) obtained after 280 adaptive cycles corresponding to 840 days of evolution were increased by 161.87 and 311.23%, respectively, at 72 h under stress conditions and increased by 19.87 and 51.79% without any stress compared with the starting strain, demonstrating the effectiveness of FS-ALE. In addition, a comparative proteomic analysis identified 11,106 proteins and 910 differentially expressed proteins, including six stress-responsive proteins, as well as the up- and downregulated pathways in FS280 that might contribute to its improved cell growth and DHA accumulation. Our study demonstrated that FS-ALE could be a valuable solution to relieve the inhibition of the fermentation supernatant at the late stage of normal fermentation of heterotrophic microalgae.

Keywords: Crypthecodinium cohnii; DHA content; adaptive laboratory evolution; fermentation supernatant; growth; quantitative proteomics.