Effects of lead on tolerance, bioaccumulation, and antioxidative defense system of green algae, Cladophora

• Low concentrations of Pb2+ accelerate Cladophora growth.
• The total soluble sugar content of Cladophora was affected by Pb2+ treatment.
• The peroxidase(POD) and metallothionein(MT) help Cladophora to survive in Pb-contaminated environments.
• The malondialdehyde (MDA) activity of Cladophora gradually increased as Pb2+ concentration increased.
• Cladophora can accumulate Pb, the adsorption on Cladophora is not a simple surface adsorption.

Effects of various concentrations (0.5, 1.0, 2.5, 5.0, 7.5, and 10.0 mg/L) of lead (Pb2+) on the growth, bioaccumulation, and antioxidative defense system of green algae, Cladophora, was investigated. Low concentrations of Pb2+ accelerated Cladophora growth, but concentrations of 10.0 mg/L and above inhibited the growth because of the hinderance to photosynthesis. The total soluble sugar content of Cladophora was affected by Pb2+ treatment, but the protein content showed no significant changes. The malondialdehyde (MDA) content and peroxidase(POD) activity of Cladophora gradually increased whereas superoxide dismutase(SOD) decreased with Pb2+ concentrations. Catalase (CAT) activity exhibited no significant changes following Pb2+ treatment. Pb2+ accumulated in Cladophora and that the lead content in Cladophora was correlated with POD growth, MDA, and Metallothionein (MT). POD and MT play a role in the survival of Cladophora in Pb-contaminated environments. This study suggests that Cladophora can be a choice organism for the phytoremediation of Pb-polluted coastal areas.