ABSTRACT:
Microalgae are free living microorganisms present in a variety of aquatic habitats. They are the primary producers of all water bodies. They have been used as a food source and for the treatment of various ailments for over two thousand years. Their neutraceutical values are recently recognized and are found as an excellent source of pigments and macromolecular contents. Nevertheless, the alarming ozone depletion causes an increase in ultraviolet radiation (UVR) in the natural environment. Among the UVR, UV-ß cause adversely on the growth and metabolism of microalgae. In this study, isolated microalgae Nannochloropsis sp. and Synechocystis sp. are cultivated in walne’s medium. UV-ß treated cultures were examined for growth kinetics and pigments like chlorophyll, carotenoids, phycobilins etc. The impact of UVR on the macromolecular contents like protein, carbohydrates and lipids were also studied. It is found that UV-radiation seriously affected the growth, pigment production except chlorophyll a, total chlorophyll in both Nannochloropsis sp. and Synechocystis sp. Likewise the UV- ß exposure decreased the carbohydrate and lipid production, but increased the protein content in both of the microalgal isolates.