Showing papers on "Chlorococcum published in 2007"

Comparative toxicity of hydrophobic contaminants to microalgae and higher plants

Abstract: To enable rapid and sensitive screening of phytotoxic compounds in terrestrial system, a 4 day solid-phase microalgal bioassay was developed. Three species of microalgae (Selenastrum capricornutum, Chlorococcum hypnosporum and Chlorococcum meneghini) were chosen to investigate their responses to DDTs (DDT, DDD and DDE) and PAHs (naphthalene, phenanthrene and pyrene) spiked sands. The bioassay results showed that PAHs and DDTs were toxic to microalgae in a 4-day exposure tests but not to seed germination of ryegrass (Lolium perenne). Phenanthrene was the most phytotoxic. Among three investigated endpoints, fluorescence emissions by microalgae were less sensitive than cell density (optical density OD650) and chlorophyll a concentration as endpoints. In general, S. capricornutum was the most sensitive species for PAHs (EC50 for phenanthrene = 9.4 mg kg−1), while C. meneghini for DDTs (EC50 for DDE = 20.0 mg kg−1). Comparison of the microalgal tests with US EPA standard seed germination/root elongation test (using Lolium perenne) demonstrated the superior screening potential of phytotoxic hydrophobic compounds using the proposed bioassay. Using OD650 as the endpoint, EC10 of selected microalgae for PAHs and DDTs were 0.43–64.3 mg kg−1 and 0.67–117 mg kg−1 respectively, which were much lower than the EC10 of L. perenne for both PAHs (94–187 mg kg−1) and DDTs (113–483 mg kg−1). The results encourage further studies involving wider types of vascular plants and more comparison with standard phytotoxicity tests from different authorities using contaminated soils to verify the effectiveness of the microalgal bioassay.

Screening of PAHs and DDTs in sand and acrisols soil by a rapid solid-phase microalgal bioassay

Abstract: Previously we have demonstrated the rapid screening potential of a newly developed solid-phase microalgal bioassay with spiked sands. In this paper, we report further comparative results using both PAHs and DDTs spiked sands and field-collected acrisols soils. Toxicity responses obtained from standard higher plant tests with three species of plants (Lolium perenne, Cynodon dactylon and Brassica chinensis) were compared with those obtained from a cocktail of microalgae (Selenastrum capricornutum, Chlorococcum hypnosporum and the indigenous Chlorococcum meneghini). The 5-day seed germination/root elongation tests were not sensitive at all in contrast to the 4-day solid-phase microalgal tests and the 28-day early seedling growth tests in both spiked sands and contaminated soils. Sensitivities of microalgal tests were generally higher than the seedling growth tests in spiked sands. Concerning the assays with contaminated soil, the responses of microalgae and higher plants varied. However, the results demonstrated that microalgae could generally act as effective surrogates to screen xenobiotic compounds at toxic level to higher plants, with the local species C. meneghini especially sensitive to reveal phytotoxic effects. This promising rapid screening solution is possible to be used in accompany with standard seedling growth tests when assessing phytotoxicities of contaminated areas, especially for acrisols soil.

The effects of Pb2+ stress on Chlorococcum sp.

Abstract: The effects of different concentration Pb2+ (0. 1,1,10,50,100,200,400 mg/L) in BG11 on the growth, morphostructure and physiological characteristics of Chlorococcum sp. were studied. Compared with the cell cultured in BG11, the cell cultured in low concentrations ( 50 mg/L) became thicker, and the pigment decreased and the pyrenoid disappeared. When the concentrations of Pb2+ were 0.1 - 10 mg/L,the growth of Chlorococcum sp. showed no obvious difference compared with the control;when the concentration of Pb2+ was 50 mg/L, Chlorococcum sp. could maintain certain growth rate yet; however, when the concentration of Pb2+ was higher than 100 mg/L, the growth of Chlorococcum sp. was inhibited markedly. The contents of Chl a + Chl b or Chl a decreased gradually with the increase of the concenrations of Pb2+ in the medium. The photosynthesis of Chlorococcum sp. 2, 2, decreased gradually with the increase of Pb2+ Concentrations, when the concentration of Pb2+ was higher than 100 mg/L, the photosynthesis of Chlorococcum sp. could not be detected; when the concentration of Pb2+ was less than 50 mg/L,the respiration of Chlorococcum sp. increased gradually with the increase of Pb2+ concentrations, and when the concentration of Pb2+ was higher than 50 mg/L, they decreased gradually with the increase of Pb2+ concentrations. The content of malondiadehyde and activities of superoxide dismutase and peroxidase increased gradually with the increase of Pb2+ concentrations, and the activity of catalase increased at beginning and then decreased with the increase of Pb2+ concentrations. When the concentration of Pb2+ was 95 %, and it was up 56.7% yet when the concentration of Pb2+ was 400 mg/L. The results demonstrated that the Chlorococcum sp. could be applied to the treatment of wastewater containing Pb2+, because the Chlorococcum sp. could endure the stress of Pb2+ and was of high removal rate on Pb2+.

THE EFFECTS OF Zn~(2+) STRESS ON THE GROWTH,PHYSIOLOGICAL CHARACTERISTICS AND CELL STRUCTURE OF CHLOROCOCCUM SP.

Abstract: In the Zn2+ stress experiments,the concentrations of Zn2+ were 0.1,1,10,50,100,200 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 a+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 catalase 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+.

The effects of Zn2+ stress on the growth, physiological characteristics and cell structure of Chlorococcum sp.

Abstract: 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+.