Photoperiod influences endogenous indoleamines in cultured green alga Dunaliella bardawil.

Effect of light intensity and photoperiod on growth, indoleamines and carotenoid production was studied in unicellular green algae D. bardawil. Maximum biomass and carotenoid contents were found when cultures were grown in light (intensity of 2.0 Klux) at a photoperiod of 16/8h light and dark cycle. There was a profound influence of tested photoperiod conditions of light:dark viz. 8:16, 10:14, and 12:12 hr, continuous light on indoleamines (SER and MEL) production as estimated by HPLC and confirmed by mass spectral data obtained from LC-MS-ESI studies. Serotonin level increased from 908 to 1765 pg/g fresh wt with increase in light duration and melatonin level increased from 267 to 584 pg/g fresh wt during increase in dark phase. Carotenoids production was high in continuous light than other tested conditions.