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首页> 外文会议>1998 Joint Conference on the Environment, 1998, Mar 31-Apr 1, 1998, Albuquerque, NM >Effects of Carboxyl-group Esterification on Metal Binding Ability of Synechococcus SP PCC 7942 (Cyanobacteria)
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Effects of Carboxyl-group Esterification on Metal Binding Ability of Synechococcus SP PCC 7942 (Cyanobacteria)

机译：羧基酯化对Syechococcus SP PCC 7942（蓝细菌）金属结合能力的影响

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摘要

Since the beginning of the industrial revolution there has been a dramatic increase in the amount of pollution released in the earth's biosphere. With these increases in levels of contamination, there comes a drastic increase in the harmful impact of both the ecological system and public health. More specifically, the increase in heavy metal contamination in aqueous environments has caused a marked increase in concern for public health. Although there are methods for heavy metal removal, such as ion exchange resins, these methods are both costly and can be harmful to workers. Thus, there is a need to develop some environmentally friendly processes that are inexpensive and safe to use. One such process that has become of increased interest is the use of biological systems to remove heavy metal ions from contaminated waters. Cyanobacteria (also known as blue-green algae) are oxygen evolving organisms that respond to stress conditions such as heavy metal contamination and light deprivation. They are one of the largest groups of photosynthetic prokaryotes and have been proven to be significant in their ability to remove metal ions from solution. For example, Spirulina platensis, when grown under contaminated conditions, contained detectable levels of both mercury and lead. Further, this species of Cyanobacteria was proven to bind copper(II), zinc(II), cadmium(II), lead(II) and iron(II) under immobilized conditions. Also, investigators have studied and proven the biosorption of heavy metals by various algal biomasses. Synechococcus sp. PCC 7942 was found to possess a copper-transporting protein within its thylakoid membrane which may help in its binding ability. Studies have been conducted to attempt to identify particular cell wall constituents responsible for metal binding. Investigators, using NMR spectroscopy to investigate cadmium binding, found evidence that binding of this metal occurs via a carboxylic group attachment. Studies of various other biomasses have shown carboxyl groups, found on the cell walls of dead algal biomass, to be responsible for binding of copper(II); and, further, proved that esterification of these functional groups results in a marked decrease in the binding of these ions. Synechococcus sp. PCC 7942 has been proven to bind significant amounts of copper(II), lead(II), nickel(II) and cadmium(II) under batch conditions with an optimal pH of 5. The purpose of this study is to expand on this information by developing a better understanding of the mechanism as well as the functional groups responsible for this metal binding ability. Until now, there has not been a study conducted in order to find out such information. Synechococcus sp. PCC 7942 was exposed to acidic methanol in attempts to esterify its carboxyl functional groups with the idea that this esterification would significantly decrease the amount of binding by the biomass. After such exposure, experiments were conducted to compare the binding ability of esterified biomass to this ability by unesterified biomass. Further, these experiments compared the difference in binding by both biomasses under two different pH conditions.
机译：自工业革命开始以来，地球生物圈释放的污染量急剧增加。随着污染水平的增加，生态系统和公共卫生的有害影响也急剧增加。更具体地说，水性环境中重金属污染的增加引起公众对健康的关注显着增加。尽管有一些去除重金属的方法，例如离子交换树脂，但是这些方法既昂贵又对工人有害。因此，需要开发一些廉价且使用安全的环保方法。引起人们越来越多关注的一种这样的方法是使用生物系统从受污染的水中去除重金属离子。蓝细菌（也称为蓝绿藻）是对压力条件（例如重金属污染和轻度剥夺）作出反应的放氧生物。它们是最大的光合作用原核生物之一，并已被证明在从溶液中去除金属离子方面具有重要意义。例如，螺旋藻在污染条件下生长时，含有可检测水平的汞和铅。此外，已证明该蓝藻物种在固定条件下结合铜（II），锌（II），镉（II），铅（II）和铁（II）。同样，研究人员已经研究并证明了各种藻类生物质对重金属的生物吸附。球菌发现PCC 7942在类囊体膜中具有铜转运蛋白，这可能有助于其结合能力。已经进行了研究以试图确定引起金属结合的特定细胞壁成分。研究人员使用NMR光谱法研究了镉的结合，发现有证据表明这种金属的结合是通过羧基附着而发生的。对各种其他生物质的研究表明，在死藻生物质的细胞壁上发现的羧基可与铜（II）结合。并且进一步证明，这些官能团的酯化导致这些离子的结合显着降低。球菌事实证明，PCC 7942在最佳pH为5的间歇条件下能结合大量的铜（II），铅（II），镍（II）和镉（II）。本研究的目的是扩展此信息通过更好地了解这种金属结合能力的机理以及官能团，可以更好地理解这一点。到目前为止，还没有进行研究以找出此类信息。球菌PCC 7942暴露于酸性甲醇中，试图酯化其羧基官能团，其想法是这种酯化将显着降低生物质的结合量。暴露后，进行实验以比较酯化生物质与未酯化生物质的结合能力。此外，这些实验比较了两种生物质在两种不同pH条件下结合的差异。

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