CAROTENOID CONTENT IN GROWING CELLS OF HAEMATOCOCCUS-PLUVIALIS DURINGA SUNLIGHT CYCLE

Under certain culture conditions, cells of the chlorophyte Haematococc us pluvialis accumulate significant amounts of astaxanthin. This study describes biomass and carotenoid production during a sunlight cycle i n a continuous culture of growing cells of H. pluvialis and shows that these two parameters are under the control of irradiance. The hourly carotenoid production increases with light intensity and, in our cultu re conditions, carotenoid accumulation occurs in a few hours and witho ut any morphological change in the algae. These carotenoids seem to be efficient in protecting algal cells against photoinhibition damage if their content is greater than 1 % dry biomass. Below this concentrati on, that is to say in the early hours of high light intensity, dry bio mass decreases due to cell lysis. The results demonstrate that seconda ry carotenoid accumulation in H. pluvialis may occur in the active gro wth phase and is stimulated from the first hours of sunlight illuminat ion.