Metabolic, Physiological, and Transcriptomics Analysis of Batch Cultures of the Green Microalga <i>Chlamydomonas</i> Grown on Different Acetate Concentrations
Kenny A. Bogaert,
Emilie Perez,
Judith Rumin,
Axel Giltay,
Michele Carone,
Nadine Coosemans,
Michele Radoux,
Gauthier Eppe,
Raphael D. Levine,
Francoise Remacle,
Claire Remacle
Affiliations
Kenny A. Bogaert
Theoretical Physical Chemistry, MolSys Research Unit, University of Liège, 4000 Liège, Belgium
Emilie Perez
Genetics and Physiology of Microalgae, InBios/Phytosystems Research Unit, University of Liège, 4000 Liège, Belgium
Judith Rumin
Genetics and Physiology of Microalgae, InBios/Phytosystems Research Unit, University of Liège, 4000 Liège, Belgium
Axel Giltay
Genetics and Physiology of Microalgae, InBios/Phytosystems Research Unit, University of Liège, 4000 Liège, Belgium
Michele Carone
Genetics and Physiology of Microalgae, InBios/Phytosystems Research Unit, University of Liège, 4000 Liège, Belgium
Nadine Coosemans
Genetics and Physiology of Microalgae, InBios/Phytosystems Research Unit, University of Liège, 4000 Liège, Belgium
Michele Radoux
Genetics and Physiology of Microalgae, InBios/Phytosystems Research Unit, University of Liège, 4000 Liège, Belgium
Gauthier Eppe
Mass Spectrometry Laboratory, MolSys Research Unit, University of Liège, 4000 Liège, Belgium
Raphael D. Levine
The Fritz Haber Research Center for Molecular Dynamics, Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem 91904, Israel
Francoise Remacle
Theoretical Physical Chemistry, MolSys Research Unit, University of Liège, 4000 Liège, Belgium
Claire Remacle
Genetics and Physiology of Microalgae, InBios/Phytosystems Research Unit, University of Liège, 4000 Liège, Belgium
Acetate can be efficiently metabolized by the green microalga Chlamydomonas reinhardtii. The regular concentration is 17 mM, although higher concentrations are reported to increase starch and fatty acid content. To understand the responses to higher acetate concentrations, Chlamydomonas cells were cultivated in batch mode in the light at 17, 31, 44, and 57 mM acetate. Metabolic analyses show that cells grown at 57 mM acetate possess increased contents of all components analyzed (starch, chlorophylls, fatty acids, and proteins), with a three-fold increased volumetric biomass yield compared to cells cultivated at 17 mM acetate at the entry of stationary phase. Physiological analyses highlight the importance of photosynthesis for the low-acetate and exponential-phase samples. The stationary phase is reached when acetate is depleted, except for the cells grown at 57 mM acetate, which still divide until ammonium exhaustion. Surprisal analysis of the transcriptomics data supports the biological significance of our experiments. This allows the establishment of a model for acetate assimilation, its transcriptional regulation and the identification of candidates for genetic engineering of this metabolic pathway. Altogether, our analyses suggest that growing at high-acetate concentrations could increase biomass productivities in low-light and CO2-limiting air-bubbled medium for biotechnology.
