In the Zn2+ stress experiments, the concentrations of Zn2+ were 0.1, I, 10, 50, 100, 200 and 400 mg/L, BG11 culture medium was served as the control. The results showed that Zn2+ affected markedly on the growth, physiological characteristics and cell structure of Chlorococcum sp. under certain concentration. When the concentration of Zn2+ was 0.1-1mg/L, the growth of Chlorococcum sp. showed no obvious difference compared with the control. When the concentration of Zn2+ was 10-50mg/L, Chlorococcum sp. could maintain certain growth rate yet. When the concentration of Zn2+ was higher than 100mg/L, the growth of Chlorococcum sp. was inhibited markedly. The contents of Chl alpha + Chl b and Chl a decreased gradually with the increase of the concentrations of Zn2+ in the medium. When the concentration of Zn2+ was less than 10mg/L, the photosynthesis and respiration of Chlorococcum sp. increased gradually with the increase of Zn2+ concentrations; and when the concentration of Zn2, was higher than 10mg/L, they decreased gradually with the increase of Zn2+ concentrations. The content of malondiadehyde and activity of peroxidase increased gradually with the increase of Zn2+ concentrations, and the activities of eatalase and superoxide dismutase increased at first and later decreased with the increase of Zn2+ concentrations. Compared with the cell cultured in BG11, the cell cultured in low concentrations (<= 10mg/L) showed few changes in pigment and thickness of cell wall. The cell wall of cell cultured in high concentrations of Zn2+ became thicker, and the pigment decreased and the pyrenoid disappeared. When the concentration of Zn2+ was <= 10mg/L, the removal rate of Chlorococcum sp. on Zn2+ reached the maximum and was 100%, and it was above 80% under the concentrations that Chlorococcum sp. could maintain the growth. The results demonstrated that the Chlorococcum sp. could be applied to the treatment of wastewater containing Zn2+ because the Chlorococcum sp. could endure the stress of Zn2+ and was of high removal rate on Zn2+.
Qiu Chang-En (firstname.lastname@example.org) ; Bi Yong-Hong; Hu Zheng-Yu (email@example.com).The effects of Zn2+ stress on the growth, physiological characteristics and cell structure of Chlorococcum sp.,Acta Hydrobiologica Sinica,2007,31(4):503-508