Centrifugation-induced production of triacylglycerols in Chlamydomonas reinhardtii

We found that Chlamydomonas reinhardtii, a model microalga, produces triacylglycerols (TAGs) when the cell pellet is left overnight after centrifugation. The centrifuged cells produce three times more TAGs than those cultured in a nitrogen (N) depletion condition in the first 24 h. The chloroplast membranes of the centrifuged cells are largely disrupted. In addition, the accumulated TAGs contain only trivial amount of C18:1 (11) and C18:3 (5,9,12) fatty acids that are more abundant in TAGs accumulated under N-starved condition. Overall, TAGs that are induced by centrifugation contain more saturated fatty acids than that induced by N starvation. These suggest that the centrifugation triggers the production of TAGs through yet unknown mechanism. An importance of this finding is that not only quantity but also quality of the TAG production can be modified by alternating environmental stimuli rather than genetic means.