AQDS and Redox-Active NOM Enables Microbial Fe(III)-Mineral Reduction at cm-Scales

• DOI: 10.1021/acs.est.9b07134
• Publication Date: 2020-02-28T16:18:16Z
• Authors: Yuge Bai; Adrian Mellage; Olaf A. Cirpka; Tianran Sun; Largus T. Angenent; Stefan B. Haderlein; Andreas Kappler
• Keywords: Ferrihydrite; Electron acceptor; Electron donor

Redox-active organic molecules such as anthraquinone-2,6-disulfonate (AQDS) and natural matter (NOM) can act electron shuttles thus facilitating transfer from Fe(III)-reducing bacteria (FeRB) to terminal acceptors Fe(III) minerals. In this research, we examined the length scale over which shuttling occur. We present results agar-solidified experimental incubations, containing either AQDS or NOM, where FeRB were physically separated ferrihydrite goethite by 2 cm. Iron speciation concentration measurements coupled a diffusion-reaction model highlighted clearly reduction in presence of shuttles, independent type FeRB. Based on our fitted model, rate increased 0.07 0.19 μmol d–1 with 10-fold increase concentration, highlighting dependence electron-shuttle concentration. To capture kinetics Fe(II) production, effective diffusion coefficient had be factor 9.4. Thus, postulate that cm was enabled combination molecular an hopping contribution reduced oxidized molecules. Our demonstrate NOM drive microbial across distances shed light process anoxic environments.