Abstract:In order to study the physiological and ecological toxicity of polychlorinated biphenyls (PCBs) of marine microalgae, the growth, photosynthetic pigment content, glutathione S-transferase (GST), superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, and ultrastructure of Dicrateria zhanjiangensis were compared over 7 days under 2,2ʹ,4,4ʹ,5,5ʹ-hexachlorobiphenyl (PCB153) stress. The results showed that PCB153 stress had significant effects on the growth, photosynthetic pigment content, antioxidant and detoxification related indexes of D. zhanjiangensis (P<0.05). Increasing PCB153 concentration increased the inhibition of PCB153 on the growth of D. zhanjiangensis. In the 250 μg/L stress group, all the algae cells died on day five. The content of chlorophyll a, chlorophyll c, carotenoid, total light, and pigment had decreased significantly after the PCB153 stress (P<0.05). The decreasing photosynthetic pigment level was enhanced by the increase in PCB153 concentration. The MDA content of algal cells in all stress groups increased after the PCB153 stress. SOD and GST enzyme activities were significantly increased by low concentration PCB153 (<25 μg/L). Both enzyme activities were significantly inhibited by high concentrations of PCB153 (>25 μg/L). Under short-term low concentrations of PCB153 stress, the ultrastructure of the cells changed. To be specific, the organelle morphology altered and shrunk. Under high concentrations of PCB153 stress, the integrity of the cell membrane was destroyed, leading to cell rupture, autolysis and death. PCB153 can inhibit the growth and synthesis of photosynthetic pigments of D. zhanjiangensis. Low concentrations of PCB153 can activate the antioxidant and detoxification system. This activation improves self-protection capabilities. High concentrations of PCB153 can aggravate lipid peroxidation and destroy the normal function of antioxidant and detoxification systems, causing cell rupture and death.
