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首页> 外文期刊>Applied and Environmental Microbiology >2,4,6-Trinitrotoluene Reduction by an Fe-Only Hydrogenase in Clostridium acetobutylicum
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2,4,6-Trinitrotoluene Reduction by an Fe-Only Hydrogenase in Clostridium acetobutylicum

机译：丙酮丁醇梭菌中仅铁的加氢酶还原2,4,6-三硝基甲苯

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The role of hydrogenase on the reduction of 2,4,6-trinitrotoluene (TNT) in Clostridium acetobutylicum was evaluated. An Fe-only hydrogenase was isolated and identified by using TNT reduction activity as the selection basis. The formation of hydroxylamino intermediates by the purified enzyme corresponded to expected products for this reaction, and saturation kinetics were determined with a Km of 152 μM. Comparisons between the wild type and a mutant strain lacking the region encoding an alternative Fe-Ni hydrogenase determined that Fe-Ni hydrogenase activity did not significantly contribute to TNT reduction. Hydrogenase expression levels were altered in various strains, allowing study of the role of the enzyme in TNT reduction rates. The level of hydrogenase activity in a cell system correlated (R2 = 0.89) with the organism's ability to reduce TNT. A strain that overexpressed the hydrogenase activity resulted in maintained TNT reduction during late growth phases, which it is not typically observed in wild type strains. Strains exhibiting underexpression of hydrogenase produced slower TNT rates of reduction correlating with the determined level of expression. The isolated Fe-only hydrogenase is the primary catalyst for reducing TNT nitro substituents to the corresponding hydroxylamines in C. acetobutylicum in whole-cell systems. A mechanism for the reaction is proposed. Due to the prevalence of hydrogenase in soil microbes, this research may enhance the understanding of nitroaromatic compound transformation by common microbial communities.
机译：评价了氢化酶在丙酮丁醇梭菌中2,4,6-三硝基甲苯（TNT）还原中的作用。通过使用TNT还原活性作为选择基础，分离并鉴定了仅铁的氢化酶。纯化的酶形成的羟氨基中间体与该反应的预期产物相对应，饱和动力学用152μMKm确定。在野生型和缺少编码替代性Fe-Ni氢化酶的区域的突变菌株之间的比较确定了Fe-Ni氢化酶活性没有显着地促进TNT的降低。各种菌株中的氢化酶表达水平均发生了变化，从而可以研究该酶在TNT还原速率中的作用。细胞系统中氢化酶活性的水平与生物体降低TNT的能力相关（R2 = 0.89）。过表达氢化酶活性的菌株导致在后期生长阶段维持TNT降低，这在野生型菌株中通常没有观察到。表现出氢化酶表达不足的菌株产生较慢的TNT还原速率，与确定的表达水平相关。分离出的仅含铁的氢化酶是在全细胞系统中将TNT硝基取代基还原为丙酮丁醇梭菌中相应羟基胺的主要催化剂。提出了反应机理。由于土壤微生物中普遍存在氢化酶，这项研究可能会增进对常见微生物群落对硝基芳香化合物转化的理解。

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