3种增塑剂对发光菌Q67联合毒性作用定量评估

Quantitative Evaluation of Combined Toxicity Interactions of Three Plasticizers on Phtobacterium Q67

增塑剂(plasticizers,PLAs)是工业生产中广泛使用的高分子材料助剂,伴随着主产品的使用而进入环境中,很可能会对环境中的生物甚至人类的健康产生危害。因此,以3种常见的PLAs:双酚A(bisphenol A,BPA)、双酚S(bisphenol S,BPS)和三丁氧基乙基磷酸酯(tris(2-butoxyethyl)phosphate,TBEP)为研究对象,运用直接均分和均匀设计射线法分别设计二元和三元混合物体系,应用时间微板毒性分析方法系统测定3种污染物及其混合物体系对淡水发光菌青海弧菌(Vibrio qinghaiensis sp.-Q67,Q67)的毒性,应用浓度加和(concentration addition,CA)分析混合物的毒性相互作用,采用绝对残差(deviation from CA model,dCA)定量评估毒性相互作用强度,并结合热图法分析相互作用强度变化规律。采用电镜扫描分析Q67细胞形态,二苯胺显色法和考马斯亮蓝法测定Q67细胞的DNA和可溶性蛋白质大分子的泄露情况来探究3种PLAs及其混合物可能的毒性作用机理。结果表明,BPA、BPS、TBEP对Q67均具有明显的急性毒性,且急性毒性均大于长期毒性;以半数效应浓度负对数值为毒性指标,3种PLAs在同一暴露时间的毒性顺序:BPA>BPS>TBEP;混合物体系BPA-BPS呈现协同作用,而BPS-TBEP、BPA-TBEP、BPA-BPS-TBEP呈现拮抗作用,且相互作用强度均受暴露时间和混合物浓度的影响;BPA-BPS-R4射线的协同作用强度最强,dCA绝对值为0.411,BPA-BPS-TBEP-R1射线的拮抗作用最明显,dCA绝对值为0.670;3种PLAs及其混合物对Q67的作用主要通过破坏细胞的结构和形态,使其DNA和可溶性蛋白质大量流失,造成细胞大量死亡。

Plasticizers(PLAs)are widely used in industrial production as additives to polymeric materials,which enter the environment along with the main product and are likely to be hazardous to organisms in the environment and even to human health.Therefore,three common PLAs,bisphenol A(BPA),bisphenol S(BPS)and tris(2-butoxyethyl)phosphate(TBEP),were selected as research objects and their binary and ternary mixtures were designed by direct equipartition and uniform design ray methods,respectively.The toxicity of the three contaminants and their mixture systems to a freshwater luminescent bacterium Vibrio qinghaiensis sp.-Q67(Q67)was systematically determined by the time-dependent microplate toxicity analysis(t-MTA).The concentration addition model(CA)was applied to analyze the toxic interactions of mixtures and the deviation from CA model(dCA)combined with the heatmap method used to analyze the intensity and variation of toxic interactions.To investigate the possible mechanisms of toxic effects of three PLAs and their mixtures,the cell morphology of Q67 was analyzed by scanning electron microscope,and the leakage of DNA as well as soluble protein macromolecules from Q67 cells were determined by diphenylamine colorimetry and the Coomassie Brilliant Blue methods,respectively.The results showed that BPA,BPS and TBEP were all of acute toxicity to Q67,and the acute toxicity was stronger than their long-term toxicity.By selecting the negative logarithm of median effect concentration(pEC 50)as the toxicity index,the toxicity order of the three PLAs was:BPA>BPS>TBEP in the same exposure time.The mixture system BPA-BPS showed synergistic effects,while BPS-TBEP,BPA-TBEP and BPA-BPS-TBEP showed antagonistic effects whose interaction strength was influenced by exposure time and concentration.The strongest synergistic effect displayed in BPA-BPS-R4 ray with the maximum absolute value of dCA(0.411),whereas the strongest antagonistic effect showed in BPA-BPS-TBEP-R1 ray with an absolute dCA value of 0.670.The effects of the three PLAs and their mixtures on Q67 were mainly through the destruction of the structure and morphology of the cells,causing massive loss of their DNA and soluble proteins,resulting in massive cell death.