title: Dynamic microbial community associated with iron-arsenic co-precipitation products from a groundwater storage system in Bangladesh.
abstract: The prokaryotic community in Fe-As co-precipitation product from a groundwater storage tank in Bangladesh was investigated over a 5-year period to assess the diversity of the community and to infer biogeochemical mechanisms that may contribute to the formation and stabilisation of co-precipitation products and to Fe and As redox cycling. Partial 16S rRNA gene sequences from Bacteria and Archaea, functional markers (mcrA and dsrB) and iron-oxidising Gallionella-related 16S rRNA gene sequences were determined using denaturing gradient gel electrophoresis (DGGE). Additionally, a bacterial 16S rRNA gene library was also constructed from one representative sample. Biogeochemical characterization demonstrated that co-precipitation products consist of a mixture of inorganic minerals, mainly hydrous ferric oxides, intimately associated with organic matter of microbial origin that contribute to the chemical and physical stabilisation of a poorly ordered structure. DGGE analysis and polymerase chain reaction-cloning revealed that the diverse bacterial community structure in the co-precipitation product progressively stabilised with time resulting in a prevalence of methylotrophic Betaproteobacteria, while the archaeal community was less diverse and was dominated by members of the Euryarchaeota. Results show that Fe-As co-precipitation products provide a habitat characterised by anoxic/oxic niches that supports a phylogenetically and metabolically diverse group of prokaryotes involved in metal, sulphur and carbon cycling, supported by the presence of Gallionella-like iron-oxidizers, methanogens, methylotrophs, and sulphate reducers. However, no phylotypes known to be directly involved in As(V) respiration or As(III) oxidation were found.
authors.affiliation: DIVAPRA, University of Turin, Grugliasco, TO, Italy. roberta.gorra@unito.it
authors.forename: Roberta
authors.initials: R
authors.lastname: Gorra
authors.forename: Gordon
authors.initials: G
authors.lastname: Webster
authors.forename: Maria
authors.initials: M
authors.lastname: Martin
authors.forename: Luisella
authors.initials: L
authors.lastname: Celi
authors.forename: Francesca
authors.initials: F
authors.lastname: Mapelli
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Weightman
mesh_terms: D001105:Archaea / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D001151:Arsenic / Q000737:chemistry* / Q000378:metabolism; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D001459:Bangladesh; D019641:DNA, Archaeal / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D060587:Groundwater / Q000737:chemistry / Q000382:microbiology*; D007501:Iron / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D019641:DNA, Archaeal; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D007501:Iron; D001151:Arsenic