第一作者：Xiaoming Chen, Tingting Yu
通讯作者：曾宪春 教授
通讯单位：中国地质大学（武汉）
DOI:10.1016/j.jhazmat.2024.134135
锑（III）和砷（III）具有相似的化学特征，并在环境中共存。然而，它们的氧化酶具有完全不同的序列和结构。这就提出了一个耐人寻味的问题：氧化锑（III）的原核生物（SOPs）是否也能氧化砷（III），反之亦然？关于这个问题，以往的研究得出了不明确、不正确甚至相互矛盾的数据。本研究旨在解决这一问题。首先，我们制备了一个富集的 SOPs 群体，其中包括 55 个不同的 AnoA 基因，但缺少 AioAB 和 ArxAB 基因。我们发现，这些 SOPs 氧化锑（III）和砷（III）的能力相当。为了进一步证实这一发现，我们分离出了三种具有 AnoA 基因但缺乏 AioAB 和 ArxAB 基因的可培养 SOP 菌株。我们观察到，在厌氧和有氧条件下，它们也能氧化锑（III）和砷（III）。其次，我们从砷污染土壤中获得了一个富集的氧化 As（III）原核生物（AOPs）种群，其中包括 69 个不同的 AioA 基因，但缺乏 AnoA 基因。我们观察到，AOPs 群体具有显著的砷(III)氧化活性，但在有氧和厌氧条件下均缺乏可检测到的锑(III)氧化活性。因此，我们令人信服地证明，大量或很可能全部 SOPs 能氧化 As(III)，但大量或很可能全部 AOPs 不能氧化 Sb(III)。这些发现澄清了之前关于 SOPs 和 AOPs 如何氧化彼此底物的模糊、混淆、错误或矛盾之处。
Fig. 1. Phylogenetic analysis of AnoA proteins from the SOP population enriched from SbS1.
Fig. 2. Sb(III)- and As(III)- oxidizing activities of the SOP population enriched from SbS1 under aerobic and anaerobic conditions. (A) Aerobic oxidation of Sb(III) by SOP population from SbS1. (B) Anaerobic oxidation of Sb(III) by SOP population from SbS1. (C) Aerobic oxidation of As(III) by SOP population from SbS1. (D) Anaerobic oxidation of As(III) by SOP population from SbS1. (E) Comparison of Sb(III)- and As(III)-oxidizing activities of the SOP population enriched from SbS1.
Fig. 3. Sb(III)- and As(III)-oxidizing activities of Pseudomonas sp. SbOB1, Brucella sp. SbOB2, and Shinella sp. SbOB3 under aerobic and anaerobic conditions, demonstrating that SbOB1, SbOB2, and SbOB3, each possessing AnoA gene but lacking AioAB and ArxAB genes, exhibit significant As(III)-oxidizing activities under both aerobic and anaerobic conditions. (A) Aerobic oxidation of Sb(III) by the three strains. (B) Anaerobic oxidation of Sb(III) by the three strains. (C) Aerobic oxidation of As(III) by the three strains. (D) Anaerobic oxidation of As(III) by the three strains. (E) Comparison of their Sb(III)- and As(III)-oxidizing activities.
Fig. 4. Phylogenetic analysis of AioA proteins from the AOP population enriched from AsS1.
Fig. 5. As(III)- and Sb(III)-oxidizing activities by the AOP population enriched from AsS1 under aerobic and anaerobic conditions. (A) Aerobic oxidation of As(III) by AOP population from AsS1. (B) Anaerobic oxidation of As(III) by AOP population from AsS1. (C) Aerobic oxidation of Sb(III) by AOP population from AsS1. (D) Anaerobic oxidation of Sb(III) by AOP population from AsS1.
Fig. 6. As(III)- and Sb(III)-oxidizing activities of Agrobacterium sp. AsOB1, Ensifer sp. AsOB2, and Achromobacter sp. AsOB3 under aerobic and anaerobic conditions. (A) As(III) oxidation curve of AsOB1 under aerobic conditions. (B) As(III) oxidation curve of AsOB2 under aerobic conditions. (C) As(III) oxidation curve of AsOB3 under aerobic conditions. (D) As(III) oxidation curve of AsOB1 under anaerobic conditions. (E) As(III) oxidation curve of AsOB2 under anaerobic conditions. (F) As(III) oxidation curve of AsOB3 under anaerobic conditions. (G) Strain AsOB1 had no Sb(III) oxidation activity under aerobic conditions. (H) Strain AsOB2 had no Sb(III) oxidation activity under aerobic conditions. (I) Strain AsOB3 had no Sb(III) oxidation activity under aerobic conditions. (J) Strain AsOB1 had no Sb(III) oxidation activity under anaerobic. (K) Strain AsOB2 had no Sb(III) oxidation activity under anaerobic conditions. (L) Strain AsOB3 had no Sb(III) oxidation activity under anaerobic conditions.
总之，本文对环境中锑和砷的生物转化提供了有价值的见解，解决了以往关于 SOP 和 AOP 能力的不确定性和误解。这些发现对环境科学、生物修复策略以及与自然系统中同时存在锑和砷有关的风险评估具有重要意义。
Xiaoming Chen, Tingting Yu, Linhai Xiao, Xian-Chun Zeng,
Can Sb(III)-oxidizing prokaryote also oxidize As(III) under aerobic and anaerobic conditions, and vice versa?, Journal of Hazardous Materials, 2024, https://doi.org/10.1016/j.jhazmat.2024.134135
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