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Published on: December 19, 2017
Hydrogen oxidation coupled to dissimilatory arsenate reduction: A potentially widespread pathway associated with
Duanyi Huang1, Xiaoxu Sun2, Wenjie Lin3
1National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China; Guangdong-Hong Kong-Macao Joint Laboratory for Environmental Pollution and Control, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; College of Environmental Science and Engineering, Hunan University, Changsha 410082, China.
Abstract:
In aquatic environments, the arsenic (As) mobilization from anoxic sediments is an important process affecting water quality and associated health risks, as sediment-bound As can serve as a persistent secondary source to overlying waters and groundwater systems. Dissimilatory arsenate reduction (DAsR) is a key microbial process releasing dissolved As(III), yet the role of inorganic electron donors in this pathway remains poorly constrained. Although hydrogen (H₂) is thermodynamically favorable for arsenate respiration, its role in arsenate reduction in natural sediments remains insufficiently resolved. In this study, hydrogen oxidation coupled to arsenate reduction (HOAsR) was investigated using sediments from an As-contaminated, mining-impacted river system. Microcosm incubations showed that H₂ amendment stimulated As(V) reduction under anoxic conditions. DNA-stable isotope probing combined with metagenomics identified Sulfuritalea, Dechloromonas, and a Moorellia-related lineage as putative HOAsR-associated populations. Corresponding metagenome-assembled genomes encoded both H₂ uptake [NiFe]-hydrogenases and the dissimilatory arsenate reductase gene (arrA). Comparative genome analysis further revealed that ∼75% of arrA-containing genomes harbor H₂ uptake [NiFe]-hydrogenases, suggesting that H₂ oxidation represents a phylogenetically widespread metabolic trait among DAsR bacteria. Analysis of public riverine metagenomes further indicated that HOAsR-associated genetic configurations are broadly distributed across sediment microbial communities. Together, these results indicated that HOAsR is a biologically plausible and geographically widespread potential pathway contributing to arsenic mobilization in anoxic sediments.
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