Metabolomic analysis of the green microalga Chlamydomonas reinhardtii cultivated under day/night conditions

Rémi Willamme; Zouheir Alsafra; Rameshkumar Arumugam; Gauthier Eppe; Françoise Remacle; R D Levine; Claire Remacle

doi:10.1016/j.jbiotec.2015.04.013

Metabolomic analysis of the green microalga Chlamydomonas reinhardtii cultivated under day/night conditions

J Biotechnol. 2015 Dec 10:215:20-6. doi: 10.1016/j.jbiotec.2015.04.013. Epub 2015 May 2.

Authors

Rémi Willamme¹, Zouheir Alsafra², Rameshkumar Arumugam³, Gauthier Eppe², Françoise Remacle⁴, R D Levine⁵, Claire Remacle⁶

Affiliations

¹ Genetics and Physiology of Microalgae, Institute of Botany, B22, University of Liège, Belgium.
² Centre of Analytical Research and Technology (CART) - LSM/Inorganic Analytical Chemistry, Department of Chemistry, B6C, University of Liège, Belgium.
³ The Fritz Haber Research Center for Molecular Dynamics, Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
⁴ The Fritz Haber Research Center for Molecular Dynamics, Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem 91904, Israel; Theoretical Physical Chemistry, Department of Chemistry, B6C, University of Liège, Belgium.
⁵ The Fritz Haber Research Center for Molecular Dynamics, Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem 91904, Israel; Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA.
⁶ Genetics and Physiology of Microalgae, Institute of Botany, B22, University of Liège, Belgium. Electronic address: c.remacle@ulg.ac.be.

PMID: 25941156
DOI: 10.1016/j.jbiotec.2015.04.013

Abstract

Biomass composition of Chlamydomonas reinhardtii was studied during two consecutive cycles of 12h light/12h dark. As in our experimental conditions the two synchronized divisions were separated by 20h, it was possible to show that accumulation of dry weight, proteins, chlorophyll and fatty acids mainly depends on cell division, whereas starch accumulation depends on a circadian rhythm as reported previously. Our metabolomics analyses also revealed that accumulation of five (Ser, Val, Leu, Ile and Thr) of the nine free amino acids detected displayed rhythmicity, depending on cell division while Glu was 20-50 times more abundant than the other ones probably because this free amino acid serves not only for protein synthesis but also for biosynthesis of nitrogen compounds. In addition, we performed a thermodynamic-motivated theoretical approach known as 'surprisal analysis'. The results from this analysis showed that cells were close to a steady state all along the 48h of the experiment. In addition, calculation of free energy of cellular metabolites showed that the transition point, i.e. the state which immediately precedes cell division, corresponds to the most unstable stage of the cell cycle and that division is identified as the greatest drop in the free energy of metabolites.

Keywords: Chlamydomonas; Day/night cycle; Metabolomics; Surprisal analysis.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Algal Proteins / analysis
Amino Acids / analysis
Biomass
Cell Division
Chlamydomonas reinhardtii / growth & development
Chlamydomonas reinhardtii / metabolism*
Chlorophyll / analysis
Circadian Rhythm
Fatty Acids / analysis
Metabolomics*

Substances

Algal Proteins
Amino Acids
Fatty Acids
Chlorophyll