Abstract：
Microbial oxidation and the mechanism of Sb(III) are key governing elements in biogeochemical cycling. A novel Sb oxidizing bacterium, Klebsiella aerogenes HC10, was attracted early and revealed that extracellular metabolites were the main fractions driving Sb oxidation. However, linkages between the extracellular metabolite driven Sb oxidation process and mechanism remain elusive. Here, model phenolic and quinone compounds, i.e., anthraquinone-2,6-disulfonate (AQDS) and hydroquinone (HYD), representing extracellular oxidants secreted by K. aerogenes HC10, were chosen to further study the Sb(III) oxidation mechanism. N2 purging and free radical quenching showed that oxygen-induced oxidation accounted for 36.78% of Sb(III) in the metabolite reaction system, while hydroxyl free radicals (·OH) accounted for 15.52%. ·OH and H2O2 are the main driving factors for Sb oxidation. Radical quenching, methanol purification and electron paramagnetic resonance (EPR) analysis revealed that ·OH, superoxide radical (O2•-) and semiquinone (SQ-•) were reactive intermediates of the phenolic induced oxidation process. Phenolic-induced ROS are one of the main oxidants in metabolites. Cyclic voltammetry (CV) showed that electron transfer of quinone also mediated Sb(III) oxidation. Part of Sb(V) was scavenged by the formation of the secondary Sb(V)-bearing mineral mopungite [NaSb(OH)6] in the incubation system. Our study demonstrates the microbial role of oxidation detoxification and mineralization of Sb and provides scientific references for the biochemical remediation of Sb-contaminated soil.
摘要：
微生物氧化和Sb（III）的机理是生物地球化学循环中的关键控制元素。一种新型锑氧化细菌,早期吸引了产气克雷伯氏菌HC10，并揭示了细胞外代谢物是驱动Sb氧化的主要部分。然而,胞外代谢物驱动Sb氧化过程和机制之间的联系仍然难以捉摸。这里,模型酚和醌化合物，即，蒽醌-2,6-二磺酸盐（AQDS）和对苯二酚（HYD），代表K.aerogenesHC10分泌的细胞外氧化剂，被选择用于进一步研究Sb（III）氧化机理。N2吹扫和自由基猝灭表明，在代谢物反应体系中，氧诱导氧化占Sb(III)的36.78%，羟基自由基(·OH)占15.52%。·OH和H2O2是Sb氧化的主要驱动因素。自由基猝灭,甲醇纯化和电子顺磁共振（EPR）分析表明，·OH，超氧自由基（O2•-）和半醌（SQ4-）是酚类诱导氧化过程的反应中间体。酚类诱导的ROS是代谢产物中的主要氧化剂之一。循环伏安法（CV）表明，醌的电子转移也介导了Sb（III）的氧化。部分Sb（V）通过在孵育系统中形成次级含Sb（V）的矿物镁铁矿[NaSb（OH）6]而被清除。我们的研究证明了Sb的氧化解毒和矿化的微生物作用，为Sb污染土壤的生化修复提供了科学依据。
