Oil accumulation in the model green alga Chlamydomonas reinhardtii: characterization, variability between common laboratory strains and relationship with starch reserves
By M. Siaut, S. Cuiné, Caroline Cagnon, Boris Fessler, M. Nguyen, P. Carrier, A. Beyly, F. Beisson, C. Triantaphylidès, Y. Li-Beisson and 1 more. BMC Biotechnology, 2011
745 citations recorded by the source corpus.
BackgroundWhen cultivated under stress conditions, many microalgae species accumulate both starch and oil (triacylglycerols). The model green microalga Chlamydomonas reinhardtii has recently emerged as a model to test genetic engineering or cultivation strategies aiming at increasing lipid yields for biodiesel production. Blocking starch synthesis has been suggested as a way to boost oil accumulation. Here, we characterize the triacylglycerol (TAG) accumulation process in Chlamydomonas and quantify TAGs in various wild-type and starchless strains.ResultsIn response to nitrogen deficiency, Chlamydomonas reinhardtii produced TAGs enriched in palmitic, oleic and linoleic acids that accumulated in oil-bodies. Oil synthesis was maximal between 2 and 3 days following nitrogen depletion and reached a plateau around day 5. In the first 48 hours of oil deposition, a ~80% reduction in the major plastidial membrane lipids occurred. Upon nitrogen re-supply, mobilization of TAGs started after starch degradation but was completed within 24 hours. Comparison of oil content in five common laboratory strains (CC124, CC125, cw15, CC1690 and 11-32A) revealed a high variability, from 2 μg TAG per million cell in CC124 to 11 μg in 11-32A. Quantification of TAGs on a cell basis in three mutants affected in starch synthesis (cw15sta1-2, cw15sta6 and cw15sta7-1) showed that blocking starch synthesis did not result in TAG over-accumulation compared to their direct progenitor, the arginine auxotroph strain 330. Moreover, no significant correlation was found between cellular oil and starch levels among the twenty wild-type, mutants and complemented strains tested. By contrast, cellular oil content was found to increase steeply with salt concentration in the growth medium. At 100 mM NaCl, oil level similar to nitrogen depletion conditions could be reached in CC124 strain.ConclusionA reference basis for future genetic studies of oil metabolism in Chlamydomonas is provided. Results highlight the importance of using direct progenitors as control strains when assessing the effect of mutations on oil content. They also suggest the existence in Chlamydomonas of complex interplays between oil synthesis, genetic background and stress conditions. Optimization of such interactions is an alternative to targeted metabolic engineering strategies in the search for high oil yields.
Subfields: Biochemistry, Molecular Biology, Renewable Energy, Sustainability and the Environment
View Paper: https://www.semanticscholar.org/paper/0e24de078adc93a147a003e121da2feee1620340
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Citations in the corpus
- Effect of light intensity and nitrogen starvation on CO2 fixation and lipid/carbohydrate production of an indigenous microalga Scenedesmus obliquus CNW-N. (2012, background): “Many reports in the literature (Siaut et al., 2011) mentioned that the major increases in fatty acid under nitrogen starvation conditions were saturated (palmitic acid; setaric acid) and monounsaturated (Palmitoleic acid; oleic acid) ones, similar to the results of this work (Fig.”
- Effect of various drought stresses and subsequent recovery on proline, total soluble sugar and starch metabolisms in Rice (Oryza sativa L.) varieties (2019, background): “The tendency of starch degradation under drought stress in this study approved previous studies, which suggested that starch is degraded under drought condition to provide energy and carbon when photosynthesis activity is restricted (Siaut et al., 2011).”
- The effect of sodium bicarbonate supplementation on growth and biochemical composition of marine microalgae cultures (2012, positive): “The recorded shift from PUFA to saturated and monounsaturated fatty acids is consistent with the conversion of polar membrane lipids and de novo synthesis of fatty acids into intracellular lipid droplets mainly composed of triacylglycerol when cells are under nutrient stress (Tornabene et al. 1983; ”
- Glycerol and neutral lipid production in the oleaginous marine diatom Phaeodactylum tricornutum promoted by overexpression of glycerol-3-phosphate dehydrogenase (2014, background): “salina and Dunaliella viridis, and exhibited increased expression of CrGPDH2 and CrGPDH3 in response to osmotic stress, which was correlated with the accumulation of glycerol and TAG in this microalga [23,24].”
- High Lipid Induction in Microalgae for Biodiesel Production (2012, background): “Significant advances in microalgae genomics have been achieved during the last decade [103,104,106].”
- The promising future of microalgae: current status, challenges, and optimization of a sustainable and renewable industry for biofuels, feed, and other products (2018, background): “Growing algal cells under certain stress conditions can alter certain biochemical pathways, leading to enhanced synthesis of carbohydrates [100, 101].”
- Effective extraction of microalgae lipids from wet biomass for biodiesel production (2014, neutral): “[31], by dissolving 0.”