Document Type : Research Paper
University of Guilan
Effects of ultraviolet (UV) radiation on biological matter became an important issue over the past three decades since the first reports of man-made changes in stratospheric ozone layer, which covers and protects the earth’s surface from harmful ultraviolet radiation. The aim of this study was to evaluate and compare the effects of different intensities of UV radiation on the physiological indices of microalgaes Chlorella sp. and Anabaena sp. After preparation of pure samples Anabaena sp. and Chlorella sp. were transferred to flasks containing the appropriate medium and then exposed to UV-C radiation at various time intervals (1, 3, 6 and 12 h) with three replicates. The treated and control samples were placed to growth chamber in favorable conditions of temperature 25±2°C, with light intensity of 2500 lux and light period of 12 hours light and 12 hours darkness in aerated condition for 12 days. The results showed that by increasing the intensity of UV-C radiation up to 12 hours factors like the growth, growth rate, content of photosynthetic pigments and total protein content based on dry weight was significantly reduced when compared to control. Also, in both microalgae, Malondialdehyde (MDA) content was increased in comparison with control group. Furthermore, comparison of the two microalgae revealed that, Anabaena sp. showed more reduction in examined parameters which indicated that the Anabaena sp. is a more sensitive species.