SECONDARY CAROTENOID PRODUCTION IN GREEN-ALGAE

Carotenoids are widespread in living organisms. All the photosynthetic organisms contain carotenoids in their thylakoid membranes performing important role in the photochemical functions. Some green algae produ ce large amounts of carotenoids which accumulate outside the thylakoid s and are known as secondary carotenoids. Two such organisms which hav e commercial importance are Dunaliella and Haematococcus which produce beta-carotene and astaxanthin, respectively. In this paper we discuss the biosynthetic pathway of carotenoids in these two organisms and th e conditions under which they are synthesized. Their physiological rol e and commercial importance is also dealt with. For commercially viabl e production of these carotenoids, the existing strains can be improve d to have carotenoid overproducing strains. Genes responsible for caro tenoid synthesis are being isolated and this shall facilitate rapid st rides in the research towards understanding their biosynthesis and fur ther manipulation.