UV-B effects on Antarctic Chlorella sp cells

ESTEVEZ MS; MALANGA G; PUN TARULO S

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2001 vol. 62 p. 19 - 25

1011-1344

Growth of Antarctic Chlorella sp cells was measured in cultures irradiated with 30 kJ m UV-B (280?320 nm). The specific growth 21 rate immediately after the lag phase was 0.3660.06 and 0.2660.03 day for unirradiated cultures and cultures irradiated with UV-B, respectively. UV-B irradiation significantly decreased ascorbate content by 54.5%, and increased the ascorbyl radical content / ascorbate content ratio by 2.25-fold in algae cultures in log phase. UV-B exposure significantly decreased by 95, 62 and 71% the content of a-tocopherol, b-carotene and total thiols, respectively, in cells in log phase of development. The cellular content of a-tocopherol, b-carotene and total thiols was reduced by 78, 43 and 44%, respectively in stationary phase, as compared to the antioxidant content in the cells during log phase of development. UV-B exposure reduced the content of a-tocopherol and total thiols in stationary phase of development by 64 and 91%, respectively, as compared to unirradiated cells. The content of b-carotene in stationary phase was not affected by UV-B exposure. The results presented here suggest that increased UV-B radiation was responsible for the development of oxidative stress conditions, assessed as the ascorbyl radical content / ascorbate content ratio, in Antarctic Chlorella sp cells. Moreover, a significant decrease in the content of both lipid and water soluble antioxidants might contribute to establish oxidative stress in the cells.