Carbon and energy metabolism for the mixotrophic culture of Chlorella vulgaris using sodium acetate as a carbon source

Xi Yan; Shengzhou Shan; Xiaohui Li; Qingshan Xu; Xiaojun Yan; Roger Ruan; Pengfei Cheng

doi:10.3389/fmicb.2024.1436264

Carbon and energy metabolism for the mixotrophic culture of Chlorella vulgaris using sodium acetate as a carbon source

Front Microbiol. 2024 Oct 23:15:1436264. doi: 10.3389/fmicb.2024.1436264. eCollection 2024.

Authors

Xi Yan¹, Shengzhou Shan¹, Xiaohui Li¹, Qingshan Xu², Xiaojun Yan³, Roger Ruan⁴, Pengfei Cheng¹

Affiliations

¹ College of Food Science and Engineering, Ningbo University, Ningbo, Zhejiang, China.
² Lijiang Cheng Hai Bao Er Biological Development Co., Ltd., Lijiang, Yunnan, China.
³ School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, China.
⁴ Center for Biorefining, and Department of Bioproducts and Biosystems Engineering, University of Minnesota-Twin Cities, Saint Paul, MN, United States.

Abstract

There has been an emergence of a diversity of microalgal mixotrophic synergistic mechanisms due to substrate differences. In this study, the effects of the mixotrophic culture of Chlorella vulgaris were examined. The maximum values of cell density, specific growth rate, and cell dry weight of Chlorella vulgaris were 3.52*10⁷ cells/mL, 0.75 d^-1, and 3.48 g/L in the mixotrophic mode, respectively. These were higher than the corresponding values of photoautotrophic or heterotrophic modes. Moreover, it was found that the concentrations of sodium bicarbonate consumed by the Chlorella vulgaris under mixotrophic and photoautotrophic modes were 635 mg/L/d and 505 mg/L/d, respectively; the concentrations of sodium acetate consumed by the Chlorella vulgaris under mixotrophic and heterotrophic modes were 614 mg/L/d and 645 mg/L/d, respectively. The activity of Rubisco was 9.36 U/mL in the mixotrophic culture, which was 3.09 and 4.85 times higher than that of the photoautotrophic and heterotrophic modes, respectively. This indicated that the differences for the carbon source absorption efficiency of Chlorella vulgaris in the mixotrophy led to different internal metabolic efficiencies when compared to photoautotroph or heterotrophy. Additionally, Chlorella vulgaris exhibits a more rapid energy metabolism efficiency when operating in the mixotrophic mode.

Keywords: Chlorella vulgaris; carbon and energy metabolism; metabolic network; mixotrophic culture; sodium acetate.

Grants and funding

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This research was supported in part by grants from the National Key R&D Program of China (2022YFE0135800), the National Natural Science Foundation of China (32170369), the Natural Science Foundation of Zhejiang Province (LZJWY22B070001), the Yunnan Key Laboratory of Microalgae (202105AG070013), the LiDakSum Marine Biopharmaceutical Development Fund, and the National 111 Project of China, University of Minnesota MnDrive Environment Program MNE12, and University of Minnesota Center for Biorefining.