莱茵衣藻的双酚A毒性效应及生物富集和降解作用研究

Toxic Effect for Bisphenol A to Chlamydomonas reinhardtii and Its Bioaccumulation and Biodegradation

为探究双酚A（BPA）对藻类的毒性及藻类对BPA的生物富集和降解作用，以模式生物莱茵衣藻（Chlamydomonas reinhardtii）为实验材料，设置了6组不同浓度的BPA（0、4、6、8、10和12mg/L），测定了莱茵衣藻的生长速率、叶绿素质量浓度、丙二醛（malondialdehyde，MDA）、超氧化物歧化酶（superoxide dismutase，SOD）和过氧化氢酶（catalase，CAT）等典型指标，并进一步用高效液相色谱一质谱（HPLC—MS）测定了BPA在藻细胞内、培养基内的含量随时间的变化。结果表明：BPA浓度为4-6mg／L时，衣藻的生长速率及叶绿素质量浓度受到刺激而升高，高于10mg／L时，二者都受到抑制而降低；与空白组相比，实验组衣藻细胞中MDA的含量随BPA暴露浓度和暴露时间的增大而逐渐升高；SOD和CAT活性随着BPA浓度和作用时间的变化基本呈现为从诱导到抑制的动态过程；莱茵衣藻对BPA具有较弱的富集能力，BPA浓度为6．8、10mg／L时，藻细胞在96h时分别达到最大富集量20、120、140μg偿鲜重和最大生物富集系数（BCF）4．40、31．55、17．74；莱茵衣藻对BPA亦具有一定的降解能力，浓度为6、8、10mg／L的BPA在96h内分别有20．12％、35．44％和9．28％被藻降解，日平均生物降解量分别为0．30、0．71和0．23mg／L。

To evaluate the toxicity of bisphenol A （BPA） to algae and the bioaccumulation and biodegradation in their cells after BPA exposure, model unicellular Chlamydomonas reinhardtii were exposed to BPA at six concentrations such as 0, 4, 6, 8, 10 and 12 mg/L, and typical physiological indicators including growth rate, chlorophyll mass concentration, malondialdehyde （MDA）, superoxide dismutase （SOD） and catalase （CAT） were measured. Then further study of temporal changes of BPA concentrations by using high performance liquid chromatography- mass spectrometry （HPLC-MS） was conducted. Results showed that the growth and chlorophyll mass content of C. reinhardtii both were stimulated at relatively low levels of BPA （4-6 mg/L） but inhibited at high concentrations more than 10 mg/L. Compared with the control group, the content of MDA in experimental group went up along with the increase of BPA exposure concentration and exposure time. Activities of antioxidant enzymes including SOD and CAT showed the dynamic process from induction to suppression according to BPA concentrations and exposure time. C. reinhardtii had a weak capability for accumulation of BPA, the bioaccumalation amounts and bioconcentration factors （BCF） reached the maximal level at 96 h, which were 20, 120, 140 μg/g fresh weight and 4.40, 31.55, 17.74 respectively, with 6, 8 and 10mg/L BPA. Also C. reinhardtii showed some biodegradation capability to BPA. After 96h incubation, about 20.12%, 35.44% and 9.28% of BPA was degraded in the cultures supplemented with 6, 8 and 10 mg/L, showing an average day biodegradation amount of 0.30, 0.71 and 0.23 mg/L.