不同外源Cd(Ⅱ)对Pseudomonas aeruginosa EPS的胁迫效应--产量、组分、吸附特性变化及其机制

Coercive effects of different exogenous Cd(II)on Pseudomonas aeruginosa EPS——Changes in yield,composition,adsorption characteristics and their mechanisms

以CdCl_(2)、CdSO_(4)和Cd(NO_(3))_(2)为胁迫因子,比较了不同阴离子在胁迫/诱导过程中对Pseudomonas aeruginosa(P.aeruginosa)胞外聚合物(EPS)的产量和特性的影响以及对Cd(II)吸附性能的变化.研究发现,当Cd(NO_(3))_(2)胁迫/诱导浓度为50mg/L时,EPS产量达到214.91mg/g VSS,其中蛋白质含量达到136.75mg/g VSS,较胁迫/诱导前增加了409.31%.此时EPS的吸附性能最好,对Cd(II)的平衡吸附量最大,较胁迫/诱导前增加了近一半.HPLC分析表明,EPS蛋白质中氨基酸的变化与EPS的吸附特性密切相关.3D-EEM、XPS和FTIR结果表明,EPS中C=O、C-N和N-H含量增加,有利于重金属的结合.竞争吸附实验发现,EPS对Cd(II)的亲和力高于Zn(II).

The effects of anions on the yield and characteristics of Pseudomonas aeruginosa EPS and its performance on Cd(II)adsorption were compared by using CdCl_(2),CdSO_(4)and Cd(NO_(3))_(2)as stress factors.The results showed that the maximum EPS yield of 214.91mg/g VSS(136.75mg/g VSS in protein content)was observed for Cd(NO_(3))_(2)at a concentration of 50mg/L,which was 409.31%higher than that before stress/induction.Under this condition,the maximum adsorption capacity for Cd(II)by the EPS was achieved,which was 50%higher than that before stress/induction.HPLC analysis showed that the changes of amino acids in EPS proteins were closely related to the adsorption characteristics of EPS.The results of 3D-EEM,XPS and FTIR showed that the content of C=O,C-N and N-H in EPS increased,which was conducive to the binding of heavy metals.Through competitive adsorption experiments,it was found that EPS has a higher affinity for Cd(II)than Zn(II).