Australian Centre for Water and Environmental Biotechnology (ACWEB), Faculty of Engineering, Architecture and Information Technology, The University of Queensland, Brisbane, Queensland 4072, Australia.
Australian Centre for Water and Environmental Biotechnology (ACWEB), Faculty of Engineering, Architecture and Information Technology, The University of Queensland, Brisbane, Queensland 4072, Australia.
J Hazard Mater. 2024 Dec 5;480:136020. doi: 10.1016/j.jhazmat.2024.136020. Epub 2024 Oct 5.
The anaerobic oxidation of methane (AOM) carried out by anaerobic methanotrophic archaea (ANME) plays an important role in mitigating methane emissions from aqueous environments and has applications in bioremediation and wastewater treatment. Previous studies showed that AOM could be coupled to chromate reduction. However, the specific responsible microorganisms and the biochemical mechanisms are unclear. Herein, we showed that a consortium dominated by ANME "Candidatus Methanoperedens" was able to couple AOM to the reduction of Cr(VI) to Cr(III) at a stoichiometry close to the theoretical ratio. Quantitative distribution analysis of Cr(III) products suggested Cr(VI) was predominantly reduced via the extracellular respiratory pathways. Further Cr(III)-targeted fluorescent visualization combined with single-cell electron microscopic imaging suggested that Cr(VI) was reduced by "Ca. Methanoperedens" independently. Biochemical mechanism investigation via proteomic analysis showed proteins for nitrate reduction under nitrate-reducing conditions were significantly downregulated in Cr(VI)-reducing incubation. Instead, many multiheme cytochrome c (MHCs) were among the most upregulated proteins during the Cr(VI) reduction process, suggesting MHC-governed pathways for extracellular Cr(VI) reduction. The significant upregulation of a formate-dependent nitrite reductase during Cr(VI) reduction indicated its potential contribution to the small proportion of Cr(VI) reduction inside cells.
厌氧甲烷氧化（AOM）由厌氧甲烷营养古菌（ANME）执行，在减轻水相环境中的甲烷排放方面发挥着重要作用，并在生物修复和废水处理中有应用。先前的研究表明，AOM 可以与铬酸盐还原偶联。然而，具体的负责微生物和生化机制尚不清楚。在此，我们表明，以“疑似产甲烷菌（Ca. Methanoperedens）”为主导的共生体能够以接近于理论比值的比例将 AOM 偶联到 Cr(VI)的还原为 Cr(III)。Cr(III)产物的定量分布分析表明，Cr(VI)主要通过细胞外呼吸途径还原。进一步的 Cr(III)靶向荧光可视化结合单细胞电子显微镜成像表明，Cr(VI)被“疑似产甲烷菌（Ca. Methanoperedens）”独立还原。通过蛋白质组学分析进行的生化机制研究表明，在 Cr(VI)还原孵育中，硝酸盐还原条件下的硝酸盐还原蛋白显著下调。相反，许多多血红素细胞色素 c（MHCs）是 Cr(VI)还原过程中上调最显著的蛋白质之一，表明 MHC 控制的细胞外 Cr(VI)还原途径。在 Cr(VI)还原过程中，甲酸依赖性亚硝酸盐还原酶的显著上调表明其可能有助于细胞内一小部分 Cr(VI)的还原。
