Autotrophic antimony (Sb) oxidation coupled to nitrate reduction plays an important role in the transformation and detoxification of Sb. However, the specific oxidase involved in this process has yet to be identified. Herein, we enriched the microbiota capable of nitrate-dependent Sb(III) oxidation and identified a new Sb(III) oxidase in an uncultured member of Symbiobacteriaceae. Incubation experiments demonstrated that nitrate-dependent Sb(III) oxidation occurred in the microcosm supplemented with Sb(III) and nitrate. Both the 16S rRNA gene and metagenomic analyses indicated that a species within Symbiobacteriaceae played a crucial role in this process. Furthermore, carbon-13 isotope labelling with carbon dioxide-fixing Rhodopseudomonas palustris in combination with nanoscale secondary ion mass spectrometry revealed that a newly characterized oxidase from the dimethylsulfoxide reductase family, designated as NaoABC, was responsible for autotrophic Sb(III) oxidation coupled with nitrate reduction. The NaoABC complex functions in conjunction with the nitrate reductase NarGHI, forming a redox loop that transfers electrons from Sb(III) to nitrate, thereby generating the energy necessary for autotrophic growth. This research offers new insights into the understanding of how microbes link Sb and nitrogen biogeochemical cycles in the environment.

中文翻译：

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未培养的 Symbiobacteriaceae 成员中的硝酸盐依赖性锑氧化酶


自养锑 （Sb） 氧化与硝酸盐还原偶联在 Sb 的转化和解毒中起重要作用。然而，该过程所涉及的特定氧化酶尚未确定。在此，我们富集了能够硝酸盐依赖性 Sb（III） 氧化的微生物群，并在共生杆菌科的未培养成员中鉴定了一种新的 Sb（III） 氧化酶。孵育实验表明，硝酸盐依赖性 Sb（III） 氧化发生在补充 Sb（III） 和硝酸盐的微观世界中。16S rRNA 基因和宏基因组学分析都表明，共生菌科中的一个物种在此过程中起着至关重要的作用。此外，用二氧化碳固定红假单胞菌 palustris 结合纳米级二次离子质谱法对碳 13 同位素进行标记，表明来自二甲基亚砜还原酶家族的新表征氧化酶，命名为 NaoABC，负责自养 Sb（III） 氧化与硝酸盐还原。NaoABC 复合物与硝酸盐还原酶 NarGHI 一起发挥作用，形成一个氧化还原环，将电子从 Sb（III） 转移到硝酸盐，从而产生自养生长所需的能量。这项研究为理解微生物如何将环境中的 Sb 和氮生物地球化学循环联系起来提供了新的见解。