Lycopene accumulation and cyclic carotenoid deficiency in heterotrophic Chlorella treated with nicotine.

We studied the effects of nicotine on Chlorella regularis Y-21 grown under heterotrophic conditions. Nicotine repressed growth, doubled cell size, and changed the culture coloration from dark-green to orange. These effects are likely due to the change of the chloroplast into a red irregular vesicle. This morphological change was associated with alteration of the carotenoid composition. Lycopene accounted for more than 80% of total carotenoids in nicotine-treated cells. The red irregular vesicles had a high electron density; we supposed them to be immature chloroplasts accumulating lycopene.