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首页> 外文期刊>Applied Microbiology >O-Demethylation and Successive Oxidative Dechlorination of Methoxychlor by Bradyrhizobium sp. Strain 17-4, Isolated from River Sediment
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O-Demethylation and Successive Oxidative Dechlorination of Methoxychlor by Bradyrhizobium sp. Strain 17-4, Isolated from River Sediment

机译：缓生根瘤菌对甲氧氯的O-脱甲基和连续氧化脱氯与河底泥沙隔离的17-4应变

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O -Demethylation of insecticide methoxychlor is well known as a phase I metabolic reaction in various eukaryotic organisms. Regarding prokaryotic organisms, however, no individual species involved in such reaction have been specified and characterized so far. Here we successfully isolated a bacterium that mediates oxidative transformation of methoxychlor, including O -demethylation and dechlorination, from river sediment. The isolate was found to be closely related to Bradyrhizobium elkanii at the 16S rRNA gene sequence level (100% identical). However, based on some differences in the physiological properties of this bacterium, we determined that it was actually a different species, Bradyrhizobium sp. strain 17-4. The isolate mediated O -demethylation of methoxychlor to yield a monophenolic derivative [Mono-OH; 1,1,1-trichloro-2-(4-hydroxyphenyl)-2-(4-methoxyphenyl)ethane] as the primary degradation product. The chiral high-performance liquid chromatography (HPLC) analysis revealed that the isolate possesses high enantioselectivity favoring the formation of ( S )-Mono-OH (nearly 100%). Accompanied by the sequential O -demethylation to form the bis-phenolic derivative Bis-OH [1,1,1-trichloro-2,2-bis(4-hydroxyphenyl)ethane], oxidative dechlorination of the side chain proceeded, and monophenolic carboxylic acid accumulated, followed by the formation of multiple unidentified polar degradation products. The breakdown proceeded more rapidly when reductively dechlorinated (dichloro-form) methoxychlor was applied as the initial substrate. The resultant carboxylic acids and polar degradation products are likely further biodegraded by ubiquitous bacteria. The isolate possibly plays an important role for complete degradation (mineralization) of methoxychlor by providing the readily biodegradable substrates.
机译：在各种真核生物中，杀虫剂甲氧基氯的O-去甲基化是I期代谢反应。然而，关于原核生物，到目前为止，尚未指定和表征涉及该反应的单个物种。在这里，我们成功地从河底沉积物中分离出了一种介导甲氧基氯氧化转化的细菌，包括O-脱甲基和脱氯。发现该分离物在16S rRNA基因序列水平（100％相同）上与伊卡氏根瘤菌密切相关。但是，根据该细菌的生理特性的一些差异，我们确定它实际上是一个不同的物种，缓生根瘤菌。株17-4。分离物介导甲氧基氯的O-去甲基化，以产生单酚衍生物[Mono-OH; 1,1,1-三氯-2-（4-羟基苯基）-2-（4-甲氧基苯基）乙烷]为主要降解产物。手性高效液相色谱（HPLC）分析表明该分离物具有高对映选择性，有利于（S）-单-OH（几乎100％）的形成。伴随着顺序的O-脱甲基化反应形成双酚衍生物Bis-OH [1,1,1-三氯-2,2-双（4-羟基苯基）乙烷]，进行了侧链的氧化脱氯和单酚羧酸酸积累，随后形成多个未确定的极性降解产物。当将还原性脱氯（二氯形式）甲氧基氯用作初始底物时，分解过程进行得更快。所产生的羧酸和极性降解产物可能会被普遍存在的细菌进一步生物降解。通过提供易于生物降解的底物，分离物可能对甲氧基氯的完全降解（矿化）起重要作用。

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