Diversity and arsenic-metabolizing gene clusters of indigenous arsenate-reducing bacteria in high arsenic groundwater of
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Diversity and arsenic-metabolizing gene clusters of indigenous arsenate-reducing bacteria in high arsenic groundwater of the Hetao Plain, Inner Mongolia Yanhong Wang1 Dazhun Wei1 Ping Li1 Zhou Jiang2 Han Liu1 Chun Qing1 Helin Wang1 ●
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Accepted: 27 October 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Dissimilatory arsenate reduction from arsenic (As)-bearing minerals into highly mobile arsenite is one of the key mechanisms of As release into groundwater. To detect the microbial diversity and As-metabolizing gene clusters of indigenous arsenate-reducing bacteria in high As groundwater in the Hetao Plain of Inner Mongolia, China, three anaerobic arsenate-reducing bacteria were isolated and arrA and arsC gene-based clone libraries of four in situ groundwater samples were constructed. The strains IMARCUG-11(G-11), IMARCUG-C1(G-C1) and IMARCUG-12(G-12) were phylogenetically belonged to genera Paraclostridium, Citrobacter and Klebsiella, respectively. They could reduce >99% of 1 mM arsenate under anoxic conditions with lactate as a carbon source in 60 h, 72 h and 84 h, respectively. As far as we know, this was the first report of arsenate reduction by genus Paraclostridium. Compared with strain G-11 (arsC) and G-C1 (arsRBC), strain G-12 contained two incomplete ars operons (operon1: arsABC, operon2: arsBC), indicating that these strains might present different strategies to resist As toxicity. Phylogenetic analysis illuminating by the arrA genes showed that in situ arsenate-reducing bacterial communities were diverse and mainly composed of Desulfobacterales (53%, dominated by Geobacter), Betaproteobacteria (12%), and unidentified groups (35%). Based on the arsC gene analysis, the indigenous arsenate-reducing bacterial communities were mainly affiliated with Omnitrophica (88%) and Deltaproteobacteria (11%, dominated by Geobacter and Syntrophobacterales). Results of this study expanded our understanding of indigenous arsenicreducing bacteria in high As groundwater aquifers. Keywords High arsenic groundwater Arsenate-reducing bacteria Isolation Diversity Arsenic-metabolizing gene clusters ●
Introduction As a worldwide environmental issue, exposure to high arsenic (As) groundwater has affected more than 140 million people from countries such as Bangladesh, China, Vietnam and the USA (Barringer et al. 2011; Harvey et al.
Supplementary information The online version of this article (https:// doi.org/10.1007/s10646-020-02305-1) contains supplementary material, which is available to authorized users. * Ping Li [email protected] 1
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, PR China
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School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China
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2002; Li et al. 2014; Winkel et al. 2011). Groundwater arsenic can originate from geogenic As-laden iron (Fe) oxide minerals (Fendorf et al. 2010) or anthropogenic utilization of As-containing fertilizer
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