城市回用水中多环芳烃的含量及对p53基因的诱变作用

p53 Gene Mutation Induced by Polycyclic Aromatic Hydrocarbons in Reclaimed Water Used in a City

目的探讨城市回用水中多环芳烃类物质(PAHs)的含量及对p53基因的诱变作用。方法于2005年8月,分别采集某城市污水处理厂回用水处理工艺中的入水和回用水,采用固相萃取法萃取其中的有机物,采用气相色谱-质谱法检测水样中16种PAHs的含量。向处于对数生长期的L-02细胞中加入提取物,使终浓度分别为50、25、12.5、6.25、3.12、1.56μl/ml,以DMSO为溶剂对照,进行四唑盐比色试验(MTT试验),并计算细胞存活率。向处于对数生长期的L-02细胞中加入提取物,使终浓度分别为0.84、1.68、3.34μl/ml,采用DNA抽提试剂盒(上海华舜生物有限公司)提取细胞中基因组DNA并测序。结果入水和回用水中均检测出PAHs,芴和菲含量最高,入水中分别达785.6、515.8ng/L,回用水中分别达685.8、312.0ng/L,其次分别为萘、苊、芘、荧蒽、二氢苊、蒽等。入水、回用水水样中16种PAHs的总浓度分别为1777.9、1380.1ng/L。经过回用水工艺处理后,回用水中PAHs含量均有所降低。与对照组比较,所有剂量组细胞存活率均降低,除了1.56μl/ml组外,差异均有统计学意义(P<0.01),并呈剂量-反应关系。目标DNA测序分析显示,入水和回用水提取物均可引起p53基因外显子5的碱基序列发生突变,但未引起p53基因外显子4、6、7、8的碱基序列发生突变。结论城市回用水中含有PAHs且具有潜在的p53基因诱变作用,提示需进一步改进城市回用水的处理工艺。

Objective To study the p53 gene mutation induced by organic extract of reclaimed water used in a city. Methods The organic extract of reclaimed water was collected by C 18 solid-phase extraction （SPE） and the 16 kinds of polycyclic aromatic hydrocarbons （PAHs） in the reclaimed water were analyzed using gas chromatography-mass spectrometry （GC-MS）. L-02 cells were treated with the organic extract of the reclaimed water at 0.84, 1.68, 3.34 μl/ml for 24 h. DNA samples forp53 mutation detection was extracted from the cells and subjected to DNA sequencing for detection of mutations in exon 5 of the p53 gene. Results All 16 kinds of PAHs were detected both in input water and reclaimed water. The predominant ones were fluorene and phenanthrene, then naphthalene, acenaphthene, acenaphthylene, anthracene, fluoranthene, pyrene and so on. Total PAHs concentration was 1 777.9 ng/L in the input water and 1380.1 ng/L in the reclaimed water. Mutation in exon 5 within thep53 gene was detected in L-02 cells treated with the organic extract of the water. Conclusion PAHs in water can be removed by sewage treatment technology at present, but the remaining PAHs can still induce the mutation of p53 gene, so using reclaimed water has some potential health impacts, the sewage treatment technology employed today should be improved.