Effect of green and red light in lipid accumulation and transcriptional profile of genes implicated in lipid biosynthesis in Chlamydomonas reinhardtii.

Microalgae have the potential to accumulate triacylglycerols under different light spectra. In this work, Chlamydomonas reinhardtii was grown under white (400-700 nm), red (650 nm), and green (550 nm) lights. According to our results, red light (650 nm) has a positive effect in the microalgae growth and chlorophyll concentration. About the lipid content, the control culture (white light-illuminated) reached a 4.4% of dry cell weight (dcw), whereas the culture grown at 550 nm showed an increase of 1.35-fold in the lipids accumulation (5.96% dcw). Interestingly, the most significant accumulation was found in the culture grown at 650 nm (14.78% dcw) which means 3.36-fold higher with respect to the white light-illuminated culture. The most abundant fatty acids found in lipid extracts obtained from the cultures under different light wavelength were palmitic (C16: 0), oleic (C18: 1n9), stearidonic (C18: 4), and linoleic (C18: 2), which are useful in the biodiesel production. Changes in gene expression in response to different wavelength illuminations were assessed; however, an in-depth analysis of a larger number of genes involved in lipid biosynthesis is necessary to fully explain the highest accumulation of lipids in the culture grown under red light. This approach will be useful to find a sustainable source of lipids for biodiesel production. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1404-1411, 2016.