多元抗生素与重金属混合物对蛋白核小球藻的时间依赖性协同与拮抗作用

Time-dependent synergism and antagonism within multi-component mixtures of heavy metals and antibiotics towards Chlorella pyrenoidosa

为探讨水环境中典型污染物抗生素和重金属的联合毒性相互作用,以蛋白核小球藻(Chlorella pyrenoidosa,C.pyrenoidosa)为指示生物,采用96孔微板作为实验载体,以5种氨基糖苷类抗生素——硫酸阿米卡星(AMI)、硫酸庆大霉素(GEN)、硫酸卡那霉素(KAN)、硫酸巴龙霉素(PAR)、妥布霉素(TOB)和4种重金属——镉(Cd)、铜(Cu)、锰(Mn)和锌(Zn)为目标混合物,应用均匀设计射线法设计九元混合物体系,包括10条具有不同组分浓度配比的混合物射线。采用已建立的时间依赖微板毒性分析法系统测定了组分及其多元混合物体系的毒性,采用非线性最小二乘法拟合浓度-毒性数据,应用浓度加和参考模型分析在不同暴露时间的多元混合物体系的毒性相互作用。结果表明:9种污染物对C.pyrenoidosa的毒性具有明显的时间依赖性,但不同污染物的毒性随时间变化规律不同,毒性大小顺序也随时间不断发生变化,毒性大小顺序在96 h为:KAN<TOB<Zn<Mn<Cd<AMI<GEN<Cu<PAR;九元混合物射线的毒性也具有时间依赖性,但浓度配比不同射线的毒性随时间变化规律不同;10条混合物射线对C.pyrenoidosa的毒性具有协同和拮抗作用,且具有明显的时间依赖性,其中R5~R7三条混合物射线呈现明显的时间依赖性拮抗作用,且随暴露时间的延长而趋于明显,余下7条混合物射线呈现明显的时间依赖性协同作用,但随暴露时间的延长而逐渐减弱;对同一暴露生物,混合物毒性相互作用不仅与混合物的组分浓度配比有关,也与暴露时间有关。

To investigate the joint toxicity of antibiotics and heavy metals, we selected Chlorella pyrenoidosa as a test organism, with a 96-well microplate as the exposure experiment carrier. Five kinds of aminoglycoside antibiotics ：amikacin sulfate（AMI）, gentamicin sulfate（GEN）, kanamycin sulfate（KAN）, paromomycin sulfate（PAR）, tobramycin（TOB）and four heavy metals：cadmium, copper, manganese and zinc were selected as the research objects. A nine-component mixture system was designed by the uniform design ray method where 10 rays with different concentration ratios（pis） were arranged. The toxicity of the mixture components and each mixture ray were deter-mined by time-dependent microplate toxicity analysis（t-MTA）. The obtained toxicity data in different exposure time were fitted by the non-linear least squares method. Concentration addition was selected and so the additive reference model to analyze toxicity interaction within mixture rays. The results showed that the toxicity of antibiotics and heavy metals was time-dependent, as were the toxicity orders of antibiotics and heavy metals. For the exposure time of 96 h, the toxicity order was KANTOBZnMnCdAMIGENCuPAR. The toxicity of the mixture rays was also time-dependent, and their toxicity orders also varied with time. The toxicity of the 10 mixture rays displayed obviously time-dependent synergism and antagonism. Three rays, R5, R6 and R7, showed time-dependent antagonism, which grew clearer with time. The remaining seven rays showed clear synergism, with time-dependency decreasing gradually.