六价铬对普通小球藻的急性毒性效应

Acute toxic effects of hexavalent chromium on Chlorella vulgaris

为探究重金属铬在水环境中的致毒机理和生态风险,本实验开展不同浓度Cr^(6+)(0、0.1、0.75、1.5、2.25和3 mg/L)对受试生物普通小球藻(Chlorella vulgaris)的急性毒性实验,分析藻密度、叶绿素a(Chl-a)含量、多糖含量、蛋白(TP)含量、活性氧自由基(ROS)含量、丙二醛(MDA)含量、细胞膜通透性、总抗氧化(T-AOC)能力、总超氧化物歧化酶(T-SOD)活性、谷胱甘肽(GSH)含量、植物螯合肽(PCs)含量和吸附效率等指标的影响。研究结果表明在96 h内Cr^(6+)各浓度组均会抑制藻细胞的生长,其中3 mg/L处理组抑制率最高,为57.32%,96 h-IC_(50)为2.067 mg/L。叶绿素a(Chl-a)含量和藻细胞生物量的变化呈现一致性,3 mg/L处理组最低,仅为对照组的26.60%。藻细胞胞内多糖和TP含量随着胁迫浓度的升高而降低。胁迫浓度的增加诱导了ROS含量的升高,3 mg/L浓度组ROS水平为对照组的6倍,MDA含量呈现相同趋势。此时藻细胞受到氧化损伤,细胞膜通透性显著增强,抗氧化体系受到激活,T-AOC、T-SOD、PCs和GSH酶活性在3 mg/L浓度组时分别为对照组的2.89倍、3.4倍、6.37倍和2.35倍。低浓度0.1 mg/L时重金属吸附率最高,高达76.00%。

The acute toxicity of different concentrations of Cr^(6+)(0,0.1,0.75,1.5,2.25 and 3 mg/L)on Chlorella vulgaris was studied to explore the toxic mechanism and ecological risk of heavy metal chromium in the water environment..The effects of algae density,chlorophyll a(Chl-a)content,polysaccharide content,total protein(TP)content,reactive oxygen species(ROS)content,malondialdehyde(MDA)content,cell membrane permeability,total antioxidant capacity(T-AOC),total superoxide dismutase(T-SOD)activity,glutathione(GSH)content,plant chelating peptide(PCs)content and adsorption rate were analyzed.The results showed that all concentration groups of Cr^(6+)could inhibit the growth of algal cells within 96 h,and the inhibition rate of the 3 mg/L treatment group was the highest(57.32%).The IC_(50)of 96 h was 2.067 mg/L.The changes in chlorophyll a(Chl-a)content and algal cell biomass were consistent,and the 3 mg/L treatment group was the lowest,only 26.60%of the control group.The contents of intracellular polysaccharides and TP in algal cells decreased with the increase of stress concentration.The increase of stress concentration induced the increase of ROS content,the ROS level in the 3 mg/L concentration group was sixtimes that of the control group,and the MDA content showed the same trend.At this time,the algal cells were subjected to oxidative damage,the cell membrane permeability was significantly enhanced,and the antioxidant system was activated.The activities of T-AOC,T-SOD,PCs and GSH in the 3 mg/L group were 2.89 times,3.4 times,6.37 times,and 2.35 times that of the control group,respectively.At a low concentration of 0.1 mg/L,the adsorption rate of heavy metals was the highest,up to 76.00%.The results provide a theoretical basis for the evaluation of the impact of heavy metal Cr^(6+)on the ecological environment.