BACKGROUND Swep is an excellent carbamate herbicide that kills weeds by interfering with metabolic processes and inhibiting cell division at the growth point. Due to the large amount of use, swep residues in soil and water not only cause environmental pollution but also accumulate through the food chain, ultimately pose a threat to human health. This herbicide is degraded in soil mainly by microbial activity, but no studies on the biotransformation of swep have been reported. RESULTS In this study, a consortium consisting of two bacterial strains, Comamonas sp. SWP-3 and Alicycliphilus sp. PH-34, was enriched from a contaminated soil sample and shown to be capable of mineralizing swep. Swep was first transformed by Comamonas sp. SWP-3 to the intermediate 3,4-dichloroaniline (3,4-DCA), after which 3,4-DCA was mineralized by Alicycliphilus sp. PH-34. An amidase gene, designated as ppa, responsible for the transformation of swep into 3,4-DCA was cloned from strain SWP-3. The expressed Ppa protein efficiently hydrolyzed swep and a number of other structural analogues, such as propanil, chlorpropham and propham. Ppa shared less than 50% identity with previously reported arylamidases and displayed maximal activity at 30 °C and pH 8.6. Gly449 and Val266 were confirmed by sequential error prone PCR to be the key catalytic sites for Ppa in the conversion of swep. CONCLUSIONS These results provide additional microbial resources for the potential remediation of swep-contaminated sites and add new insights into the catalytic mechanism of amidase in the hydrolysis of swep.

中文翻译：

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由两株菌群组成的除草剂药草的矿化作用，并表征了用于水解药草的新型酰胺酶。

背景技术Sweep是一种优异的氨基甲酸酯除草剂，可通过干扰代谢过程并抑制生长点的细胞分裂来杀死杂草。由于大量使用，残留在土壤和水中的残留物不仅会造成环境污染，而且还会在食物链中积聚，最终对人类健康构成威胁。该除草剂主要通过微生物活性在土壤中降解，但尚未有关于草ep的生物转化的报道。结果在这项研究中，由两个细菌菌株Comamonas sp。组成的财团。SWP-3和Alicycliphilus sp。PH-34从受污染的土壤样品中富集，并具有矿化扫除的能力。Swep首先由Comamonas sp。改造。将SWP-3合成为中间体3,4-二氯苯胺（3,4-DCA），然后通过Alicycliphilus sp。将3,4-DCA矿化。PH-34。从菌株SWP-3克隆了一个酰胺酶基因，命名为ppa，负责将swep转化为3,4-DCA。表达的Ppa蛋白有效地水解了swap和许多其他结构类似物，例如丙炔，氯丙胺和丙胺。Ppa与以前报道的阿拉伯酰胺酶的同一性低于5​​0％，并且在30°C和pH 8.6下显示出最大活性。Gly449和Val266通过易错序列PCR证实是swa转化中Ppa的关键催化位点。结论这些结果提供了潜在的补救sweep污染位点的额外微生物资源，并为酰胺酶在sweep水解中的催化机理提供了新的见解。表达的Ppa蛋白有效地水解了swap和许多其他结构类似物，例如丙炔，氯丙胺和丙胺。Ppa与以前报道的阿拉伯酰胺酶的同一性低于5​​0％，并且在30°C和pH 8.6下显示出最大活性。Gly449和Val266通过易错序列PCR证实是swa转化中Ppa的关键催化位点。结论这些结果提供了潜在的补救sweep污染位点的额外微生物资源，并为酰胺酶在sweep水解中的催化机理提供了新的见解。表达的Ppa蛋白有效地水解了swap和许多其他结构类似物，例如丙炔，氯丙胺和丙胺。Ppa与以前报道的阿拉伯酰胺酶的同一性低于5​​0％，并且在30°C和pH 8.6下显示出最大活性。Gly449和Val266通过易错序列PCR证实是swa转化中Ppa的关键催化位点。结论这些结果提供了潜在的补救sweep污染位点的额外微生物资源，并为酰胺酶在sweep水解中的催化机理提供了新的见解。Ppa与以前报道的阿拉伯酰胺酶的同一性低于5​​0％，并且在30°C和pH 8.6下显示出最大活性。Gly449和Val266通过易错序列PCR证实是swa转化中Ppa的关键催化位点。结论这些结果提供了潜在的补救sweep污染位点的额外微生物资源，并为酰胺酶在sweep水解中的催化机理提供了新的见解。Ppa与以前报道的阿拉伯酰胺酶的同一性低于5​​0％，并且在30°C和pH 8.6下显示出最大活性。Gly449和Val266通过易错序列PCR证实是swa转化中Ppa的关键催化位点。结论这些结果提供了额外的微生物资源，用于潜在地补救被sweep污染的位点，并为酰胺酶在sweep水解中的催化机理提供了新的见解。