Nutritive Substitution of Zinc by Cadmium and Cobalt in Phytoplankton Isolated from the Lower Great Lakes
Nutritive Substitution of Zinc by Cadmium and Cobalt in Phytoplankton Isolated from the Lower Great Lakes
复制标题
从五大湖下游分离的浮游植物中镉和钴对锌的营养替代
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
M. Twiss
中科院分区：
文献类型：
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作者：
A. Intwala;Tara D. Patey;Damien Polet;M. Twiss
低环境浓度的微量金属包括锌可能会限制北美五大湖浮游植物的生产力。研究了五大湖原生微藻小球藻（Chlorella sp. UTCC 522）和Cyclotella sp. UTCC 520 （Heterokontophyta）在Zn生物利用度限制条件下对Zn的需水量以及Co和Cd对Zn的代谢替代能力。在实验室使用化学定义的培养基和金属缓冲剂EDTA进行生物测定，以控制Zn2+(10−15.3-10−10 mol/L)、Cd2+(10−15.1-10−10 mol/L)和Co2+(10−14-10−10 mol/L)的自由离子浓度。通过对浮游植物特定生长率的影响来测量金属对浮游植物的影响。两种微藻均需用Zn，均可利用Co和Cd作为Zn的代用物；虽然硅藻Cyclotella比绿藻小球藻更有效地利用Cd，但Cd的利用效率较低。浮游植物利用Cd和Co作为Zn替代品的能力表明，微藻在大型湖泊Zn、Cd和Co的地球化学循环以及受污染影响的湖泊生态系统中Cd的动员中发挥了重要作用。
ABSTRACT Low ambient concentrations of trace metals including Zn may limit phytoplankton productivity in the North American Great Lakes. The microalgae Chlorella sp. UTCC 522 (Chlorophyta) and Cyclotella sp. UTCC 520 (Heterokontophyta), indigenous to the Great Lakes, were assayed for their Zn requirement and the ability for Co and Cd to metabolically substitute for Zn under conditions in which Zn bioavailability was limiting cell growth. Bioassays were conducted in the laboratory using chemically defined media and the metal buffer EDTA to control the free-ion concentrations of Zn2+ (10−15.3–10−10 mol/L), Cd2+ (10−15.1–10−10 mol/L), and Co2+ (10−14–10−10 mol/L). Influence of the metals on the phytoplankton was measured by the effect on specific growth rate. Both microalgae required Zn and could use Co and Cd as Zn substitutes; Cd was used less-effectively, although to a greater extent by the diatom Cyclotella than by the chlorophyte, Chlorella. The observed ability of the phytoplankton to use Cd and Co as Zn substitutes suggests that microalgae play an important role in the geochemical cycling of Zn, Cd and Co in large lakes, and the mobilization of Cd in lake ecosystems impacted by pollution.