首页|Mechanism of extracellular electron transport and reactive oxygen mediated Sb(Ⅲ)oxidation by Klebsiella aerogenes HC10
Mechanism of extracellular electron transport and reactive oxygen mediated Sb(Ⅲ)oxidation by Klebsiella aerogenes HC10
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Mechanism of extracellular electron transport and reactive oxygen mediated Sb(Ⅲ)oxidation by Klebsiella aerogenes HC10
Microbial oxidation and the mechanism of Sb(Ⅲ)are key governing elements in biogeo-chemical cycling.A novel Sb oxidizing bacterium,Klebsiella aerogenes HC10,was attracted early and revealed that extracellular metabolites were the main fractions driving Sb ox-idation.However,linkages between the extracellular metabolite driven Sb oxidation pro-cess 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 rad-icals(·OH)accounted for 15.52％.·OH and H2O2 are the main driving factors for Sb oxida-tion.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.
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