Evidence for facilitated uptake of Hg(II) by Vibrio anguillarum and Escherichia coli under anaerobic and aerobic conditions
Evidence for facilitated uptake of Hg(II) by Vibrio anguillarum and Escherichia coli under anaerobic and aerobic conditions
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DOI：
10.4319/lo.2002.47.4.0967
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发表时间：
2002-07-01
影响因子：
4.5
通讯作者：
Barkay, T
中科院分区：
文献类型：
--
作者：
Golding, GR;Kelly, CA;Barkay, T
采用mer-lux生物报告器研究了两种兼性厌氧细菌——鳗弧菌和大肠杆菌对微量浓度的无机汞Hg（II）的吸收。这些细菌对汞（II）的吸收似乎是促进的，而不是被动扩散。有三条证据支持这一结论。首先，在厌氧条件下，与好氧条件相比，Hg（II）的吸收大大减少，即使培养基的化学成分相同，只是缺氧（即没有使用还原剂）。其次，厌氧条件下汞（II）的吸收量与亲脂性汞的丰度不成正比，而是取决于样品中汞的总浓度。第三，在微量Hg（II）浓度和厌氧条件下，添加酵母提取物和各种低分子量有机酸可以增强Hg（II）的吸收。除了证明这些细菌对汞（II）的吸收具有促进运输的特征外，这些证据还支持这样的结论，即在细胞调节控制下的过程影响了汞（II）的吸收。如果这些发现也适用于其他细菌，它们意味着目前水生系统中微生物对汞（II）的吸收模型将需要重新考虑，该模型仅基于亲脂性Ho物种的作用和被动扩散。
A mer-lux bioreporter was used to study uptake of inorganic mercury, Hg(II), at trace concentrations by two facultatively anaerobic bacterial species, Vibrio anguillarum and Escherichia coli. Uptake of Hg(II) by these bacteria appeared to be facilitated, rather than by passive diffusion. Three lines of evidence support this conclusion. First, under anaerobic conditions Hg(II) uptake was greatly decreased compared with aerobic conditions, even though the chemical composition of the medium was identical except for the lack of oxygen (i.e., no reducing agents were used). Second, the uptake of Hg(II) under anaerobic conditions was not proportional to the abundance of lipophilic Hg species but was dependent on the total concentration of Hg in the samples. Third, at trace Hg(II) concentrations and under anaerobic conditions, Hg(II) uptake was enhanced by the addition of yeast extract and a variety of low molecular weight organic acids. In addition to demonstrating that Hg(II) uptake by these bacteria had the characteristics of facilitated transport, these lines of evidence also support the conclusion that processes under regulatory control of the cell affected Hg(II) uptake. If these findings apply to other bacteria as well, they mean that current models of Hg(II) uptake by microorganisms in aquatic systems, which are based solely on the role of lipophilic Ho species and passive diffusion, will need to be reconsidered.