Chlorpyrifos contamination is a currently on-going issue with significant environmental impacts. As such, rapid and effective techniques that remove chlorpyrifos from the environment are urgently required. Here, a new strain of Pseudomonas nitroreducens W-7 exhibited exceptional degradation ability towards both chlorpyrifos and its major metabolite 3,5,6-trichloro-2-pyridinol (TCP). W-7 can effectively reduce the toxicity of chlorpyrifos and TCP towards a variety of sensitive organisms through its superior degradation capacity. W-7 demonstrated efficient soil bioremediation by removing over 50% of chlorpyrifos (25 mg/kg) from both sterile and non-sterile soils within 5 days, with significantly reduced half-lives. Additionally, 16S rDNA high-throughput sequencing of the soil revealed that the introduction of W-7 had no significant impact on the soil microbial community. A pivotal hydrolase Oph2876 containing conserved motif (HxHxDH) and a bimetallic catalytic center was identified from W-7. Oph2876 was a heat- and alkali-resistant enzyme with low sequence similarity (< 44%) with other reported organophosphorus hydrolases, with a better substrate affinity for hydrolysis of chlorpyrifos to TCP. The molecular docking and site-directed mutagenesis studies indicated that the amino acid residues Asp235, His214, and His282, which were associated with the conserved sequence “HxHxDH”, were crucial for the activity of Oph2876. These findings contribute to a better understanding of the biodegradation mechanism of chlorpyrifos and present useful agents for the development of effective chlorpyrifos bioremediation strategies.

中文翻译：

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揭示水解酶 Oph2876 介导的硝基假单胞菌降解机制及其在环境生物修复中的潜力


毒死蜱污染是目前一个持续存在的问题，对环境有重大影响。因此，迫切需要快速有效的技术来从环境中去除毒死蜱。在这里，一种新的硝基假单胞菌 W-7 菌株对毒死蜱及其主要代谢物 3,5,6-三氯-2-吡啶醇 （TCP） 表现出非凡的降解能力。W-7 通过其优越的降解能力，可以有效降低毒死蜱和 TCP 对多种敏感生物的毒性。W-7 通过在 50 天内从无菌和非无菌土壤中去除超过 25% 的毒死蜱 （25mg/kg） 来证明有效的土壤生物修复，并显着缩短了半衰期。此外，土壤的 16S rDNA 高通量测序显示，W-7 的引入对土壤微生物群落没有显着影响。从 W-7 中鉴定出一个包含保守基序 （HxHxDH） 和双金属催化中心的关键水解酶 Oph2876。Oph2876 是一种耐热碱酶，与其他已报道的有机磷水解酶具有低序列相似性 （< 44%），对毒死蜱水解为 TCP 具有更好的底物亲和力。分子对接和定点诱变研究表明，与保守序列 “HxHxDH” 相关的氨基酸残基 Asp235 、 His214 和 His282 对 Oph2876 的活性至关重要。这些发现有助于更好地了解毒死蜱的生物降解机制，并为开发有效的毒死蜱生物修复策略提供了有用的试剂。