title: Diverse arsenic- and iron-cycling microbial communities in arsenic-contaminated aquifers used for drinking water in Bangladesh.
abstract: Subsurface removal of arsenic by injection with oxygenated groundwater has been proposed as a viable technology for obtaining 'safe' drinking water in Bangladesh. While the oxidation of ferrous iron to solid ferric iron minerals, to which arsenic adsorbs, is assumed to be driven by abiotic reactions, metal-cycling microorganisms may potentially affect arsenic removal. A cultivation-independent survey covering 24 drinking water wells in several geographical regions in Bangladesh was conducted to obtain information on microbial community structure and diversity in general, and on specific functional groups capable of the oxidation or reduction of arsenic or iron. Each functional group, targeted by either group-specific 16S rRNA or functional gene amplification, occurred in at least 79% of investigated samples. Putative arsenate reducers and iron-oxidizing Gallionellaceae were present at low diversity, while more variation in potentially arsenite-oxidizing microorganisms and iron-reducing Desulfuromonadales was revealed within and between samples. Relations between community composition on the one hand and hydrochemistry on the other hand were in general not evident, apart from an impact of salinity on iron-cycling microorganisms. Our data suggest widespread potential for a positive contribution of arsenite and iron oxidizers to arsenic removal upon injection with oxygenated water, but also indicate a potential risk for arsenic re-mobilization by anaerobic arsenate and iron reducers once injection is halted.
authors.affiliation: Department of Molecular Cell Physiology, Faculty of Earth and Life Sciences, VU University Amsterdam, 1081 HV Amsterdam, the Netherlands Department of Microbiology, University of Dhaka, Dhaka-1000, Bangladesh.
authors.forename: Zahid
authors.initials: Z
authors.lastname: Hassan
authors.affiliation: Department of Microbiology, University of Dhaka, Dhaka-1000, Bangladesh.
authors.forename: Munawar
authors.initials: M
authors.lastname: Sultana
authors.affiliation: Critical Zone Hydrology Group, Department of Earth Sciences, Faculty of Earth and Life Sciences, VU University Amsterdam, 1081 HV Amsterdam, the Netherlands.
authors.forename: Boris M
authors.initials: BM
authors.lastname: van Breukelen
authors.affiliation: Department of Microbiology, University of Dhaka, Dhaka-1000, Bangladesh.
authors.forename: Sirajul I
authors.initials: SI
authors.lastname: Khan
authors.affiliation: Department of Molecular Cell Physiology, Faculty of Earth and Life Sciences, VU University Amsterdam, 1081 HV Amsterdam, the Netherlands wilfred.roling@falw.vu.nl.
authors.forename: Wilfred F M
authors.initials: WF
authors.lastname: Röling
mesh_terms: D000327:Adsorption; D001149:Arsenates; D001151:Arsenic / Q000737:chemistry / Q000378:metabolism*; D020261:Arsenic Poisoning / Q000517:prevention & control; D018053:Arsenites; D001459:Bangladesh; D020564:Deltaproteobacteria / Q000235:genetics / Q000378:metabolism; D060766:Drinking Water / Q000737:chemistry / Q000382:microbiology*; D043372:Gallionellaceae / Q000235:genetics / Q000378:metabolism; D060587:Groundwater / Q000737:chemistry / Q000382:microbiology; D007501:Iron / Q000737:chemistry / Q000378:metabolism*; D010084:Oxidation-Reduction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D018508:Water Purification / Q000379:methods*
chemical_list: D001149:Arsenates; D018053:Arsenites; D060766:Drinking Water; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D007501:Iron; C015001:arsenite; D001151:Arsenic; C025657:arsenic acid
keywords: aquifer; arsenic cycle; iron cycle; microbial redox reactions; subsurface arsenic removal; subsurface iron removal