Potential role of the Fe(III)-reducing bacteria Geobacter and Geothrix in controlling arsenic solubility in Bengal delta sediments

F. S. Islam, C. Boothman, A. G. Gault, D. A. Polya, Jon R. Lloyd

    Research output: Contribution to journalArticlepeer-review


    Previous studies from our laboratory have suggested a role for indigenous metal-reducing bacteria in the reduction of sediment-bound As(V), and have also shown that a stable enrichment culture of Fe(III)-reducing bacteria was able to mobilize arsenic (as As(III)) from sediments collected from West Bengal (Islam et al., 2004). To identify the Fe(III)-reducing bacteria that may play a role in the reduction of As(V) and mobilization of As(III), we made a detailed molecular analysis of this enrichment culture. It was dominated by a close relative of Geothrixfermentans, but the type strain of this organism was unable to conserve energy for growth via the dissimilatory reduction of As(V), or reduce As(V) present in a defined medium containing fumarate as the electron acceptor. Furthermore, when the cells were gown using soluble Fe(III)-citrate as an electron acceptor in the presence of As(V), bacterial Fe(III) reduction resulted in the precipitation of the Fe(II)-bearing mineral vivianite in 2 weeks. This was accompanied by the efficient removal of As from solution. These results demonstrate that Geothrix fermentans, in common with other key Fe(III)-reducing bacteria such as Geobacter sulfurreducens, does not reduce As(V) enzymatically, but can capture arsenic in Fe(II) minerals formed during respiration using Fe(III) as an electron acceptor. Thus, the reduction of arsenic-bearing Fe(III) oxide minerals is not sufficient to mobilize arsenic, but may result in the formation of Fe(II) biominerals that could potentially act as sinks for arsenic in sediments. Additional mechanisms, including dissimilatory As(V) reduction by other specialist anaerobic bacteria, are implicated in the mobilization of arsenic from sediments. © 2005 The Mineralogical Society.
    Original languageEnglish
    Pages (from-to)865-875
    Number of pages10
    JournalMineralogical Magazine
    Issue number5
    Publication statusPublished - Oct 2005


    • Arsenic
    • As(V) reduction
    • Bengal
    • Biogeochemistry
    • Dissimilatory metal reduction
    • Fe(III) reduction


    Dive into the research topics of 'Potential role of the Fe(III)-reducing bacteria Geobacter and Geothrix in controlling arsenic solubility in Bengal delta sediments'. Together they form a unique fingerprint.

    Cite this