Phylogenetic analysis of nitrate- and sulfate-reducing bacteria in a hydrogen-fed biofilm

Authors

  • Aura Ontiveros-Valencia,

    1. Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, AZ, USA
    2. School of Sustainability, Arizona State University, Tempe, AZ, USA
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  • Zehra Esra Ilhan,

    1. Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, AZ, USA
    2. School of Life Sciences, Arizona State University, Tempe, AZ, USA
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  • Dae-Wook Kang,

    1. Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, AZ, USA
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  • Bruce Rittmann,

    1. Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, AZ, USA
    2. School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ, USA
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  • Rosa Krajmalnik-Brown

    Corresponding author
    1. School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ, USA
    • Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, AZ, USA
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Correspondence: Rosa Krajmalnik-Brown, Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, 1001 South McAllister Ave., Tempe, AZ 85287-5701, USA. Tel.: +1 480 727 7574; fax: 1 480 727 0889; e-mail: dr.rosy@asu.edu

Abstract

Using two membrane biofilm reactors in which hydrogen (H2) was the only exogenous electron donor, we studied the microbial community structure of biofilms composed primarily of denitrifying bacteria (DB) and sulfate-reducing bacteria (SRB). In steady-state EDvSS, H2 availability was restricted and varied. In steady-state EAvSS, the input nitrate (math formula) concentration was varied relative to a fixed sulfate (math formula) concentration. SRB co-existed with DB, even when math formula reduction was absent due to restricted H2 availability. UniFrac and principal coordinate analysis indicated that H2 availability and electron-acceptor loadings framed the microbial community structure, with H2 availability having a greater impact. In EDvSS, restricted H2 availability favored heterotrophic DB (i.e. Burkholderiales) compared with autotrophic DB (e.g. Hydrogenophilales and Rhodocyclales). In EAvSS, math formula reduction lowered the relative abundance of some DB (e.g. Hydrogenophilales), and the biofilm was colonized by Desulfovibrionales and Bacteroidales. Reinforcing the impact of H2 availability, EAvSS showed a higher microbial diversity and more even distribution among microbial groups than did EDvSS. Thus, the biofilm community in a H2-fed biofilm with DB and SRB became more heterotrophic when the H2 availability was constrained, while low math formula loading allowed more math formula reduction, causing a shift to more SRB.

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