Abstract:

The response of an Arctic microalgae strain (Chlorella sp.) to the enhancement of UV-B radiation was explored in this paper. The effects of three different intensity (0 μw/cm2, 45 μw/cm2, 76 μw/cm2 ) within 12 h radiation following with 4 h non-radiation recovery were studied, while the biochemical components were tested by sampling every 4 h. Our results showed that: (1) Under the lower intensity of UV-B (45μw/cm2) radiation, Chla and Car content increased in the beginning 4 h and then decreased. The maximum value presented after 4 hrs. Meanwhile, under high-intensity UV-B (76μw/cm2) radiation, Chla and CAR content constantly decreased. (2) The content of O2?ˉ and MDA enhanced along with radiation time and intensity. Moreover, H2O2 content also increased with irradiation time; significant vary happened after 8 h radiation. (3) SOD, CAT activity under the lower UV-B treatment, increased with irradiation time as well. Under higher UV-B radiation, SOD activity increased at the beginning 4 hrs and then decreased constantly, CAT activity fluctuated from time to time.（4）The fatty acid composition of Chlorella was influenced. The results supported that UV-B had adverse effects on the Arctic glaciers microalgae, and the effect of hurt was more significant under high-intensity or high doses of UV-B.

Key words: UV-B radiation, Chlorella sp., biochemical composition