Bioaccumulation and transformation of cadmium by Phaeodactylum tricornutum  

作　　者：SI DongFang YANG LiMin YAN Hua WANG QiuQuan 

机构地区：[1]Department of Chemistry&Key Laboratory of Analytical Sciences,College of Chemistry and Chemical Engineering,Xiamen University,Xiamen 361005,China [2]State Key Laboratory of Marine Environmental Science,Xiamen University,Xiamen 361005,China

出　　处：《Science China Chemistry》2009年第12期2373-2380,共8页中国科学（化学英文版）

摘　　要：In this paper,we report the bioaccumulation and transformation of cadmium (Cd) by Phaeodactylum tricornutum in the presence of ethylenediamine tetra acetic acid (EDTA) and cysteine (Cys). Both EDTA and Cys can alleviate the toxicity of Cd to P. tricornutum. Short term intracellular uptake and extracellular adsorption experiments using ICP-MS indicated that the amounts of Cd accumulated on the cell surface of P. tricornutum and inside the cell decreased along with the increase of EDTA concentration,which conformed to the prediction of the Free Ion Activity Model (FIAM). However,extracellular adsorption of Cd increased at first and then decreased along with the increase in the concentration of Cys,while intracellular uptake increased under Cys concentrations from the blank value to 4.45 μmol/L,and then tended to remain at the same level when the Cys concentration was greater than 4.45 μmol/L,and this deviated remarkably from the FIAM. The interactions of Cd with _Si_OH,_C_OH and NH2(CO) _OH on the cell wall were confirmed using FT-IR and XPS studies. The results obtained using HPLC of the phytochelatins (PCs) produced by P. tricornutum under CdCl2,Cd_EDTA and Cd_Cys stress suggested that the main reason for the different effects of EDTA and Cys on the bioaccumulation and transformation of Cd by P. tricornutum was that Cys is not only a complexing ligand to Cd,as is EDTA,but also it is a precursor of the intracellular synthesizing PCs participating in the cellular defense mechanism against Cd. Furthermore,the discovery of in vivo PCs and oxidized_PCs as well as Cd-PC2 in P. tricornutum using ESI-IT-MS provided the evidence for deactivation of Cd by the PCs,reducing Cd-toxicity to P. tricornutum.In this paper, we report the bioaccumulation and transformation of cadmium (Cd) by Phaeodactylum tricornutum in the presence of ethylenediamine tetra acetic acid (EDTA) and cysteine (Cys). Both EDTA and Cys can alleviate the toxicity of Cd to P. tricornutum. Short term intracellular uptake and extracellular adsorption experiments using ICP-MS indicated that the amounts of Cd accumulated on the cell surface of P. tricornutum and inside the cell decreased along with the increase of EDTA concentration, which conformed to the prediction of the Free Ion Activity Model (FIAM). However, extracellular adsorption of Cd increased at first and then decreased along with the increase in the concentration of Cys, while intracellular uptake increased under Cys concentrations from the blank value to 4.45 μmol/L, and then tended to remain at the same level when the Cys concentration was greater than 4.45 μmol/L, and this deviated remarkably from the FIAM. The interactions of Cd with-Si-OH, -C-OH and NH2(CO)-OH on the cell wall were confirmed using FT-IR and XPS studies. The results obtained using HPLC of the phytochelatins (PCs) produced by P. tricornutum under CdCl2, Cd-EDTA and Cd-Cys stress suggested that the main reason for the different effects of EDTA and Cys on the bioaccumulation and transformation of Cd by P. tricornutum was that Cys is not only a complexing ligand to Cd, as is EDTA, but also it is a precursor of the intracellular synthesizing PCs participating in the cellular defense mechanism against Cd. Furthermore, the discovery of in vivo PCs and oxidized-PCs as well as Cd-PC2 in P. tricornutum using ESI-IT-MS provided the evidence for deactivation of Cd by the PCs, reducing Cd-toxicity to P. tricornutum.

关 键 词：PHAEODACTYLUM TRICORNUTUM CADMIUM BIOACCUMULATION and transformation CYSTEINE EDTA 

分 类 号：O614.242[理学—无机化学]