State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China.
ISME J. 2024 Jan 8;18(1). doi: 10.1093/ismejo/wrae204.
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 labeling 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.
自养锑（Sb）氧化与硝酸盐还原偶联在 Sb 的转化和解毒中起着重要作用。然而，该过程中涉及的特定氧化酶尚未被鉴定。本研究通过富集能够依赖硝酸盐进行 Sb(III)氧化的微生物群落，并在未培养的 Symbiobacteriaceae 成员中鉴定到一种新的 Sb(III)氧化酶。培养实验表明，在添加 Sb(III)和硝酸盐的微宇宙中发生了依赖硝酸盐的 Sb(III)氧化。16S rRNA 基因和宏基因组分析均表明，Symbiobacteriaceae 中的一个物种在该过程中起着关键作用。此外，利用固定二氧化碳的 Rhodopseudomonas palustris 进行的碳-13 同位素标记与纳米二次离子质谱联用实验表明，一种新鉴定的来自二甲基亚砜还原酶家族的氧化酶，命名为 NaoABC，负责与硝酸盐还原偶联的自养 Sb(III)氧化。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在环境中连接 Sb 和氮生物地球化学循环提供了新的见解。
