BioEnergy Research

, Volume 8, Issue 4, pp 1824–1830 | Cite as

Rapid Lipid Induction in Chlorella sp. by UV-C Radiation

  • Kalpesh K. Sharma
  • Yan Li
  • Peer M. SchenkEmail author


Rapid induction of lipid accumulation in microalgae is an important prerequisite towards the use of microalgae as a feedstock for biodiesel production. In this study, we present a novel approach to induce lipids in Chlorella sp. within 24 h by short-term UV-C radiation (UVR) stress at different energy intensities ranging from 0 to 1000 mJ/cm2. Increase in the lipid fluorescence was measured by Nile red staining and fluorescence-activated cell sorting analysis followed by gas chromatography-mass spectrometry. Lipid fluorescence was significantly increased in cultures radiated at or above 250 mJ/cm2 compared to the mock-treated control cultures. Lower dosages at 100 and 250 mJ/cm2 led to a near doubling of total fatty acids, with a significant increase in unsaturated fatty acids and also most saturated fatty acids. This study provides a protocol for rapid lipid induction of microalgal cells by UV-C and the possible impact of UV-C radiation on fatty acid metabolism.


Chlorella Lipids Microalgae PUFA UV-C 



We wish to thank the Australian Research Council for financial support.

Supplementary material

12155_2015_9633_MOESM1_ESM.pdf (214 kb)
Online Resource Figure 1 Analysis of the non-polar fraction of TAGs in Chlorella sp. BR2 treated with different UV-C radiation doses (0–1000 mJ/cm2). (PDF 213 kb)
12155_2015_9633_MOESM2_ESM.pdf (162 kb)
Online Resource Figure 2 FACS analysis of Chlorella sp. BR2. Shown are cells without Nile red staining (Unstained Cells) and Nile red-stained with different UV-C dosages ranging from 0 mJ/cm2 (Control) to 1000 mJ/cm2 showing P1 and P2 populations. The Y-axis shows fluorescence intensity at the phycoerythrin excitation wavelength of 575 nm, and the X-axis shows the forward scatter based on cell size. (PDF 161 kb)
12155_2015_9633_MOESM3_ESM.pdf (136 kb)
Online Resource Figure 3 Comparison of different saturated fatty acids present in Chlorella sp. BR2 cultures treated with different doses of UV-C radiation. Values are mean ± SE from three separately grown cultures (n = 3); bars with different letters indicate significant differences (P < 0.05). (PDF 136 kb)
12155_2015_9633_MOESM4_ESM.pdf (144 kb)
Online Resource Figure 4 Comparison of different unsaturated fatty acids present in Chlorella sp. BR2 cultures treated with different doses of UV-C radiation. Values are mean ± SE from three separately grown cultures (n = 3); bars with different letters indicate significant differences (P < 0.05). (PDF 143 kb)
12155_2015_9633_MOESM5_ESM.pdf (54 kb)
Online Resource Figure 5 Growth curve of Chlorella sp. BR2 cells. UV-C treatment was applied during the late exponential growth phase (1.6 × 107 cells/mL). Values are mean ± SE from three separately grown cultures (n = 3). (PDF 53 kb)
12155_2015_9633_MOESM6_ESM.pdf (53 kb)
Online Resource Figure 6 Comparison of total fatty acids present in Chlorella sp. BR2 cells treated with different doses of UV-C radiation. Shown are mean amounts ± SE of total fatty acids in micrograms/cell from three separately grown cultures (n = 3); bars with different letters indicate significant differences (P < 0.05). (PDF 52 kb)


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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  1. 1.Algae Biotechnology Laboratory, School of Agriculture and Food SciencesThe University of QueenslandBrisbaneAustralia

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