Effects of bromate on the growth and physiological characteristics of Chlorella vulgaris

The effects of bromate on the growth and physiological characteristics of Chlorella vulgaris were investigated via the static exposure experiments and tested by flow cytometry. The results showed that when Chlorella vulgaris was continuously exposed to bromate for 96 h at 8 mmol·L^-1, the specific growth rates and cell membrane integrity decreased significantly, while the esterase activity, mitochondrial membrane potential and reactive oxygen species (ROS) increased significantly. The membrane-damaged cells could be found from the scanning electron microscopy analysis. It could be identified that ROS were overproduced in presence of bromate, which could not be eliminated by Chlorella vulgaris in time through self-regulation. The excess ROS could lead to abnormal situation of cell membrane integrity, esterase activity and mitochondrial membrane potential, disorder of physiology function and damage of cell structure. It could be concluded that Chlorella vulgaris died or their growth was inhibited by the existence of bromate.