Pyridine-2,6-Bis(Thiocarboxylic Acid) Produced by Pseudomonas stutzeri KC Reduces and Precipitates Selenium and Tellurium Oxyanions
Pyridine-2,6-Bis(Thiocarboxylic Acid) Produced by Pseudomonas stutzeri KC Reduces and Precipitates Selenium and Tellurium Oxyanions
复制标题
施氏假单胞菌 KC 产生的吡啶-2,6-双（硫代羧酸）可还原并沉淀硒和碲氧阴离子
DOI：
10.1128/aem.72.5.3119-3129.2006
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发表时间：
2006
影响因子：
4.4
通讯作者：
A. Paszczynski
中科院分区：
文献类型：
--
作者：
A. Zawadzka;R. Crawford;A. Paszczynski
施氏假单胞菌KC的铁载体吡啶-2，6-二硫代羧酸（pdtc）对硒和碲的含氧阴离子具有解毒作用。提出了pdtc对亚碲酸盐和亚硒酸盐解毒的机理。该机制是基于使用质谱法和能量色散X射线光谱法的碲酸盐和亚硒酸盐与pdtc的初始反应过程中形成的化合物的化学结构的测定。亚硒酸盐和亚碲酸盐被pdtc或其水解产物H2S还原，形成从溶液中沉淀的零价pdtc硒化物和pdtc碲化物。然后这些不溶性化合物水解，释放出纳米级的元素硒或碲颗粒。电子显微镜研究表明，这些类金属的细菌细胞外沉淀和内部沉积。用合成的pdtc形成的沉淀物与斯氏毕赤酵母KC的pdtc产生培养物中形成的沉淀物相似。含pdtc的斯氏原杆菌KC培养液对亚硒酸盐的去除和元素硒、碲的沉淀也有一定的活性。产生pdtc的野生型菌株KC比pdtc阴性突变株CTN 1对亚硒酸盐和亚碲酸盐毒性具有更高的耐受性。这些观察结果支持的假设，pdtc不仅作为铁载体的功能，但也参与了抵御各种金属和类金属的毒性的初始防线。
ABSTRACT The siderophore of Pseudomonas stutzeri KC, pyridine-2,6-bis(thiocarboxylic acid) (pdtc), is shown to detoxify selenium and tellurium oxyanions in bacterial cultures. A mechanism for pdtc's detoxification of tellurite and selenite is proposed. The mechanism is based upon determination using mass spectrometry and energy-dispersive X-ray spectrometry of the chemical structures of compounds formed during initial reactions of tellurite and selenite with pdtc. Selenite and tellurite are reduced by pdtc or its hydrolysis product H2S, forming zero-valent pdtc selenides and pdtc tellurides that precipitate from solution. These insoluble compounds then hydrolyze, releasing nanometer-sized particles of elemental selenium or tellurium. Electron microscopy studies showed both extracellular precipitation and internal deposition of these metalloids by bacterial cells. The precipitates formed with synthetic pdtc were similar to those formed in pdtc-producing cultures of P. stutzeri KC. Culture filtrates of P. stutzeri KC containing pdtc were also active in removing selenite and precipitating elemental selenium and tellurium. The pdtc-producing wild-type strain KC conferred higher tolerance against selenite and tellurite toxicity than a pdtc-negative mutant strain, CTN1. These observations support the hypothesis that pdtc not only functions as a siderophore but also is involved in an initial line of defense against toxicity from various metals and metalloids.