Physiological responses and accumulation ability of Microcystis aeruginosa to zinc and cadmium: Implications for bioremediation of heavy metal pollution

Algae has potential to remediate heavy metals. However, the physiological responses of live algae to heavy metals are not well studied. In this study, the physiological responses of Microcystis aeruginosa to zinc (Zn) and cadmium (Cd) ions and its ability to accumulate ions were investigated. Low concentrations (<0.1 mg/l) of Zn and Cd had little influence on algal growth and physiological processes, whereas concentrations above 0.1 mg/l increased the esterase activity (from 42.5% to 621.9%), superoxide dismutase activity (from 12.8% to 45.4%), and malondialdehyde content (from 18.2% to 103.9%), and dramatically inhibited the cell division (from 12.6% to 70.0%) and photosynthetic performance (from 7.1% to 53.1%) of M. aeruginosa. The accumulation of Zn or Cd ions by M. aeruginosa increased exponentially with the initial concentration of metallic ions. Collectively, these findings reveal that M. aeruginosa has considerable potential in the remediation of freshwater lakes with heavy metal contamination during cyanobacterial blooms, where metallic ions are lower than 0.1 mg/l.