Mechanism of extracellular electron transport and reactive oxygen mediated Sb(III) oxidation by Klebsiella aerogenes HC10.

Autor:	Rong, Qun1,2 (AUTHOR), Zhang, Chaolan1 (AUTHOR) zhangcl@gxu.edu.cn, Ling, Caiyuan1 (AUTHOR), Lu, Dingtian1 (AUTHOR), Jiang, Linjiang1 (AUTHOR)
Předmět:	Reactive oxygen species Electron-transfer catalysis Electron paramagnetic resonance Electron transport Klebsiella Quinone compounds Metabolic detoxification
Zdroj:	Journal of Environmental Sciences (Elsevier). Jan2025, Vol. 147, p11-21. 11p.
Abstrakt:	• Sb(III) oxidation was mediated by AQDS and phenolic. • · OH, O 2 −• and SQ−• were found as dominant free radicals intermediates. • Oxidation was accelerated by free radical catalysis and electron transfer. • H 2 O 2 was dominant oxidant for Sb(III) oxidation in metabolites. • The secondary mineral mopungite formation sequesters part of Sb(V). 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. N 2 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 H 2 O 2 are the main driving factors for Sb oxidation. Radical quenching, methanol purification and electron paramagnetic resonance (EPR) analysis revealed that · OH, superoxide radical (O 2 •−) 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. [Display omitted] [ABSTRACT FROM AUTHOR]
Databáze:	GreenFILE
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