抗重金属土壤微藻F1对Cu2+胁迫的耐受生理机制研究

摘要

以从新疆富蕴县金属矿区土壤筛选出的抗重金属微藻F1为材料,测定在不同浓度(0、0.5、1.0、1.5和2.0mmol/L)Cu2+胁迫下F1微藻叶绿素a、可溶性蛋白、MDA和谷胱甘肽(GSH)含量,以及谷胱甘肽硫转移酶(GST)、谷胱甘肽过氧化酶(GSH-PX)和谷氨酰半胱氨酸合成酶(GCL)的活性,同时用红外光谱仪检测细胞壁上参与重金属螯合的官能团,用扫描电镜分析细胞壁上的离子交换情况,探讨F1土壤微藻对CR2胁迫的耐受生理机制,为利用微藻生态修复技术去除污染区土壤重金属奠定基础.结果显示:(1)F1土壤微藻对Cu2+具有较强的耐抗性.(2)F1土壤微藻细胞中参与吸附Cu2的基团分别为-OH、-CH2、-RCONH2和C-OH等.(3)F1土壤微藻在吸附Cu2+的过程中,Cu2 +与细胞壁上的Al3+、Fe2+、Mg2+、Ca2 +、K+、Na+和Zn2+发生了交换.(4)藻细胞中的GSH和GSH-PX在F1土壤微藻耐受Cu2+胁迫时起主要作用.研究认为,F1微藻种对Cu2+的耐受性首先与其细胞壁外表细微结构及其离子交换特性有关,并且细胞壁上-OH、-CH2、-RCONH2和C-OH等化学基团起着重要作用,其次细胞内的谷胱甘肽以及谷胱甘肽相关酶类能够有效清除活性氧的过量积累,最终保护细胞免受重金属胁迫损伤.%A heavy metal resistant strain F1 was isolated from the mining area of the Fuyun county,Xinjiang.The contents of the chlorophyll a,soluble protein,MDA and glutathione (GSH),and enzyme activity of the glutathione s-transferase (GST),glutathione peroxidase (GSH-PX) and glutamyl-cysteine synthase (GCL) were measured while the strain F1 exposed to the different concentrations(0,0.5,1.0,1.5 and 2.0 mmol/L) of Cu2+;subsequently,the functional groups involved with the heavy metal chelating process and the data related to cell wall ion exchange process were determined using infrared spectrometer and scanning electron microscope,respectively.As the results,(1) soil microalgae F1 exhibited relatively high tolerance capability against Cu2+ stress;(2)-OH,-CH2,-RCONH2 and C-OH were confirmed as the key participants of the stress tolerance process;(3) the absorption process of Cu2+ was done by exchanging other positive ions,such as AP+,Fe2+,Mg2+,Ca2+,K+,Na+ and Zn2+;(4) in algae cells,GSH and GSH-PX were the essential factors which have important role against Cu2+ stress.In conclusion,the fine structure of cell wall and its ion exchange ability were the fundamental factors in Cu2+ tolerance;in particular,those chemical groups that were examined above.Moreover,the glutathione-related enzymes protected the cell from internal damage by preventing the active oxygen from excess accumula tion,so that,protects the cell damage under the stress.