Effects of tetrabromobisphenol A on the green alga Chlorella pyrenoidosa

Flow cytometry (FC) was used to determine effects of tetrabromobisphenol A (TBBPA) on the green alga Chlorella pyrenoidosa (C. pyrenoidosa) by evaluating esterase activity, membrane integrity, concentrations of intracellular reactive oxygen species (ROS) and chlorophyll a (Chl-a) auto-fluorescence. TBBPA can inhibit esterase activity. Esterase activity was inversely proportional with TBBPA with a 24 h EC50 value of 3.13 mg TBBPA/L. After 48 h of exposure to TBBPA intracellular ROS was significantly greater than in the unexposed cells. TBBPA inhibited Chl-a fluorescence after 168 h. Concentrations of ROS were directly proportional to both magnitude and duration of exposure and was inversely proportional to cellular Chl-a. FC was useful as an integrated, ecologically relevant, measure of a functional response of the algae. The possible action pathway of TBBPA in C. pyrenoidosa is that TBBPA can cause toxic effects on esterase activity. As concentrations and exposure time increased, TBBPA change the ROS level in the internal. The role of anti-oxidative action is marked and significant at the duration of 48 h exposure, compared to the control. This suggested there was a redox cycle. TBBPA changes physiological status of cells, further decreased Chl-a fluorescence indicating inhibition.