13C-metabolic flux analysis of lipid accumulation in the green microalgae Tetradesmus obliquus under nitrogen deficiency stress

Xiaoli Li; Yulun Dong; Kai Chen; Anand Babu Perumal; Zhihao Zhan; Mostafa Gouda; Yong He

doi:10.1016/j.biortech.2023.129740

¹³C-metabolic flux analysis of lipid accumulation in the green microalgae Tetradesmus obliquus under nitrogen deficiency stress

Bioresour Technol. 2023 Nov:388:129740. doi: 10.1016/j.biortech.2023.129740. Epub 2023 Sep 15.

Authors

Xiaoli Li¹, Yulun Dong¹, Kai Chen¹, Anand Babu Perumal², Zhihao Zhan¹, Mostafa Gouda³, Yong He¹

Affiliations

¹ College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.
² College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China. Electronic address: anandbabu@zju.edu.cn.
³ College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China; Department of Nutrition & Food Science, National Research Centre, Dokki, Giza 12622, Egypt.

PMID: 37717702
DOI: 10.1016/j.biortech.2023.129740

Abstract

Metabolic fluxes (MF) serve as the functional phenotypes of biochemical processes and are crucial to describe the distribution of precursors within metabolic networks. There is a lack of experimental observations for carbon flux towards lipids, which is important for biodiesel generation. Here, the accumulation of lipid, and MF in Tetradesmus obliquus under nitrogen deficiency stress (NF) using a ¹³C isotope tracer at different time intervals was investigated. The ¹³C based MF showed enhanced de novo synthesis of G3P and PEP, indicating increased carbon flux from CO₂ into lipid synthesis. An increase in palmitic acid (3500 μmol/mg), linoleic acid (2100 μmol/mg), and oleic acid (2000 μmol/mg) was observed. The accumulation of C16:0 under NF was mainly related to de novo synthesis while C18:3 was accumulated through a non de novo pathway. Under NF stress, T. obliquus had higher flux in PPP and glycolysis pathway, together, it might provide more NADPH and substrate acetyl-CoA for fatty acid synthesis.

Keywords: (13)C Stable isotope; Chemical composition; Fatty acids; Metabolites; Oxidative stress; Pathways.