A revised mineral nutrient supplement increases biomass and growth rate in Chlamydomonas reinhardtii
Article first published online: 21 MAR 2011
© 2011 The Authors. The Plant Journal © 2011 Blackwell Publishing Ltd
The Plant Journal
Volume 66, Issue 5, pages 770–780, June 2011
How to Cite
Kropat, J., Hong-Hermesdorf, A., Casero, D., Ent, P., Castruita, M., Pellegrini, M., Merchant, S. S. and Malasarn, D. (2011), A revised mineral nutrient supplement increases biomass and growth rate in Chlamydomonas reinhardtii. The Plant Journal, 66: 770–780. doi: 10.1111/j.1365-313X.2011.04537.x
- Issue published online: 24 MAY 2011
- Article first published online: 21 MAR 2011
- Accepted manuscript online: 11 FEB 2011 04:12AM EST
- Received 16 December 2010; revised 1 February 2011; accepted 7 February 2011; published online 21 March 2011.
- inductively coupled plasma mass spectrometry;
Interest in exploiting algae as a biofuel source and the role of inorganic nutrient deficiency in inducing triacylglyceride (TAG) accumulation in cells necessitates a strategy to efficiently formulate species-specific culture media that can easily be manipulated. Using the reference organism Chlamydomonas reinhardtii, we tested the hypothesis that modeling trace element supplements after the cellular ionome would result in optimized cell growth. We determined the trace metal content of several commonly used Chlamydomonas strains in various culture conditions and developed a revised trace element solution to parallel these measurements. Comparison of cells growing in the revised supplement versus a traditional trace element solution revealed faster growth rates and higher maximum cell densities with the revised recipe. RNA-seq analysis of cultures growing in the traditional versus revised medium suggest that the variation in transcriptomes was smaller than that found between different wild-type strains grown in traditional Hutner’s supplement. Visual observation did not reveal defects in cell motility or mating efficiency in the new supplement. Ni2+-inducible expression from the CYC6 promoter remained a useful tool, albeit with an increased requirement for Ni2+ because of the introduction of an EDTA buffer system in the revised medium. Other advantages include more facile preparation of trace element stock solutions, a reduction in total chemical use, a more consistent batch-to-batch formulation and long-term stability (tested up to 5 years). Under the new growth regime, we analyzed cells growing under different macro- and micronutrient deficiencies. TAG accumulation in N deficiency is comparable in the new medium. Fe and Zn deficiency also induced TAG accumulation, as suggested by Nile Red staining. This approach can be used to efficiently optimize culture conditions for other algal species to improve growth and to assay cell physiology.