Effect of UV-B Radiation on Growth, Photosynthetic Activity and Metabolic Activities of Chlorella vulgaris
The impact of different intensities (1 Wm-2, 3 Wm-2 and 5 Wm-2) of ultraviolet-B (UV-B) radiation on growth, photosynthetic pigments, and metabolic activity has been studied in Chlorella vulgaris isolated from fresh water sample of Kulavoi lake, Chengalpet. The experimental alga Chlorella vulgaris was exposed to different intensities of 1, 3 and 5 W m-2, and different durations of 10, 15, 20, 25, 30 mins of UV-B radiation respectively. Among the different intensities and durations tested inhibited growth by 50% Chlorophyll 5 Wm-2 of UV-B after 15 min followed by decrement in cell growth. On the other hand, carotenoids were stimulated at small doses (time of exposure and intensity) at 3 or 5 W m-2 of UV-B radiation. However, total proteins and total carbohydrates were inhibited by UV-B exposure times but the effect of 5 Wm-2 was more than other two intensities. The results suggest that Chlorella vulgaris is resistant to UV-B radiation damage at lower exposure time even at higher intensity and the possible negative effect of additional UV-B radiation on the growth of microalgae may have been effectively balanced by the UV-B radiation stress through increase in UV-absorbing compounds.
Kavitha Ganapathy, Kurinjimalar Chidambaram, Ramya Janarthanan, Rengasamy Ramasamy