Effects of magnetic field on the antioxidant defense system of recirculation-cultured Chlorella vulgaris.

Little is known about the influence of magnetic fields (MF) on growth of microalgae such as Chlorella vulgaris, which has been consumed as health food for various nutritional and pharmacological effects. This preliminary study investigated whether static MF can modulate the antioxidant system in C. vulgaris by exposing the cells to static MF generated by dual yoke electromagnets with magnetic flux density of 10-50 mT for 12 h. After exposure to 10-35 mT for 12 h, the activity of superoxide dismutases and peroxidase increased significantly compared to control cells. However, a remarkable increase of catalase activity occurred at 45 and 50 mT. The lipid peroxidation of algae cells determined by production of thiobarbituric acid-reactive substances was much increased when exposed to 35, 45, and 50 mT of MF. The scavenging ability of 2,2-diphenyl-1-picrylhydrazyl radical was decreased markedly while there was no variation of total carotenoids content in C. vulgaris cells. Assay of specific growth rate in 72 h cultivation after MF exposure was also conducted. In groups after exposure to 10-35 mT of MF, specific growth rate was significantly increased. These results suggest that 10-35 mT of static MF exposure could promote the growth of C. vulgaris and regulate its antioxidant defense system to protect cells efficiently, which could possibly enhance the growth of C. vulgaris in industrialized cultivation by MF. (c) 2007 Wiley-Liss, Inc.