Naturally occurring fatty acid methyl esters and ethyl esters in the green microalga Chlamydomonas reinhardtii

Biodiesel can be defined as fatty acid methyl esters (FAMEs) or fatty acid ethyl esters (FAEE) obtained from the transesterification of triacylglycerides (TAGs) from vegetable oils and animal fats; however, oleaginous microalgae are emerging as potential substitutes of these feedstocks for biodiesel production. The use of the green microalga Chlamydomonas reinhardtii P. A. Dang as a model system for lipid metabolism studies offers the advantage that extensive physiological and genomic data are available. The presence of naturally occurring FAMEs has been reported previously in plants and microalgae. In this study, oil extracts of C. reinhardtii batch cultures at the end of the growth phase were analyzed before and after the transesterification reaction to investigate the presence of naturally occurring FAMEs in this microalga. As a result, the presence of these compounds was observed in hexane oil extracts of C. reinhardtii before transesterification. Five FAMEs were identified by gas chromatography-mass spectrometry (GC-MS) before and after transesterification, while one additional FAME appeared only after transesterification. Additionally, three FAEEs were also identified before and after the transesterification reaction. Therefore, naturally occurring FAMEs and FAEEs are reported in C. reinhardtii. These results will pave the way for further studies on the biosynthesis of these compounds in green microalgae, and their potential use as biofuels.