title: Impact of the morphology and reactivity of nanoscale zero-valent iron (NZVI) on dechlorinating bacteria.
abstract: Nanoscale zero-valent iron (NZVI) is increasingly used for reducing chlorinated organic contaminants in soil or groundwater. However, little is known about what impact the particles will have on the biochemical processes and the indigenous microbial communities. Nanoiron reactivity is affected by the structure and morphology of nanoparticles that complicates the applicability in bioremediation. In this study, the effect of precursors (ferrous sulfate and ferric chloride) and reducing agents (sodium dithionite and sodium borohydride) on the morphology and the reactivity of NZVIs was investigated. We also studied the impact of differently synthesized NZVIs on microbial community, which take part in reductive dechlorination. We demonstrated that both the applied iron precursor and the reducing agent had influence on the structure of the nanoparticles. Spherical nanoparticles with higher Fe(0) content (>90%) was observed by using sodium borohydride as reducing agent, while application of sodium dithionite as reducing agent resulted nanostructures with lower Fe(0) content (between 68,7 and 85,5%). To determine the influence of differently synthesized NZVIs on cell viability anaerobic enriched microcosm were used. NVZI was used in 0.1 g/L concentration in all batch experiments. Relative amount of Dehalococcoides, sulfate reducers (SRBs) and methanogens were measured by quantitative PCR. We found that the relative amount of Dehalococcoides slowly decreased in all experiments independently from the precursor and reducing agent, whereas the total amount of microbes increased. The only clear distinction was in relative amount of sulfate reducers which were higher in the presence of NZVIs synthesized from sodium dithionite.
authors.affiliation: Department of Applied and Environmental Chemistry, University of Szeged, Szeged, Hungary.
authors.forename: Andrea
authors.initials: A
authors.lastname: Rónavári
authors.affiliation: Bay Zoltán Nonprofit Ltd. for Applied Research, Division for Biotechnology, Szeged, Hungary.
authors.forename: Margit
authors.initials: M
authors.lastname: Balázs
authors.affiliation: Bay Zoltán Nonprofit Ltd. for Applied Research, Division for Biotechnology, Szeged, Hungary.
authors.forename: Péter
authors.initials: P
authors.lastname: Tolmacsov
authors.affiliation: Synthetic and System Biology Unit, Biological Research Centre, Szeged, Hungary.
authors.forename: Csaba
authors.initials: C
authors.lastname: Molnár
authors.affiliation: Bay Zoltán Nonprofit Ltd. for Applied Research, Division for Biotechnology, Szeged, Hungary.
authors.forename: István
authors.initials: I
authors.lastname: Kiss
authors.affiliation: Department of Applied and Environmental Chemistry, University of Szeged, Szeged, Hungary; MTA-SZTE "Lendület" Porous Nanocomposites Research Group, Szeged, Hungary.
authors.forename: Ákos
authors.initials: Á
authors.lastname: Kukovecz
authors.affiliation: Department of Applied and Environmental Chemistry, University of Szeged, Szeged, Hungary; MTA-SZTE Reaction Kinetics and Surface Chemistry Research Group, Szeged, Hungary. Electronic address: konya@chem.u-szeged.hu.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Kónya
mesh_terms: D001419:Bacteria; D001673:Biodegradation, Environmental; D060587:Groundwater / Q000737:chemistry; D054879:Halogenation; D007501:Iron / Q000737:chemistry*
chemical_list: D007501:Iron
keywords: Bioremediation; Nanoscale zero-valent iron (NZVI); Quantitative PCR; Reductive dechlorination