Microbial oxidation of Fe(II)-natural organic matter complexes
Final Report Abstract
Fe(II)-organic-matter (Fe(II)-OM) complexes are abundant in the environment and, due to their mobility, reactivity and bioavailability, may play a key role for the behavior of Fe and pollutants. Complexation of Fe has been shown to influence the rates and extent of many chemical and microbial redox reactions. However, it was unknown whether, how fast, and to which extent Fe(II)-OM complexes can be oxidized by anaerobic Fe(II)-oxidizing bacteria which are widespread in many habitats. We used thermodynamic modeling and cell-suspension experiments, and revealed the influence of Fe(II)-OM complexation on the anaerobic microbial Fe(II) oxidation by model anaerobic Fe(II)-oxidizers: Acidovorax sp. BoFeNl, Rhodopseudomonas palustris TIE-1 and Rhodobacter ferrooxidans SW2, representing two types of microbial Fe(II) oxidation. We found that Fe(II)-OM complexation has different effects on different types of microbial Fe(II)-oxidizers. Fe(II)-OM complexation inhibited microbial nitrate-reducing Fe(II) oxidation, i.e. the colloidal and negatively charged Fe(II)-OM complexes showed lower oxidation rates than free Fe(II) by nitrate-reducing Fe(II)-oxidizing bacteria. In contrast, the Fe(II)-OM complexation did not inhibit but significantly accelerate the rates of Fe(II) oxidation by microbial phototrophic Fe(II) oxidizers, with different extent depending on the identity of the Fe(II)-OM complexes. In addition, we have revealed a closer-link between microbial Fe(II) oxidation and microbial denitrification, and demonstrated a cryptic Fe-cycle in which photochemical reduction of Fe(NI)-OM complexes is coupled to microbial phototrophic oxidation of Fe(II)-OM complexes. These results suggest that Fe(II)-OM complexation has a significant influence on the rate, extent and products of microbial Fe(II) oxidation in anoxic environments, and potentially could play an important role in influencing the cycles of carbon and nitrogen in the environment.
Publications
- (2018) Microbial anaerobic Fe(II) oxidation - ecology, mechanisms and environmental implications. Environmental Microbiology, 20, 3462-3483
Bryce, C., Blackwell, N., Schmidt, C., Otte, J., Huang, Y., Kleindienst, S., Tomaszewski, E., Schad, M., Warter, V., Peng, C., Byrne, J.M., Kappler, A.
(See online at https://doi.org/10.1111/1462-2920.14328) - Oxidation of Fe(II)-Organic Matter Complexes in the Presence of the Mixotrophic Nitrate-Reducing Fe(II)-Oxidizing Bacterium Acidovorax sp. BoFeNl. Environmental Science & Technology 2018, 52, (10), 5753-5763
Peng, C., Sundman, A., Bryce, C., Catrouillet, C.,Borch, T.,Kappler, A.
(See online at https://doi.org/10.1021/acs.est.8b00953) - (2019) Organic matter complexation promotes Fe(II) oxidation by the phototrophic Fe(II)-oxidizer Rhodospseudomonas palustris TIE-1. ACS Earth and Space Science
Peng, C., Bryce, C., Sundman, A.,Borch, T.,Kappler, A.
(See online at https://doi.org/10.1021/acsearthspacechem.9b00024) - Cryptic Cycling of Complexes Containing Fe(III) and Organic Matter by Phototrophic Fe(II)-Oxidizing Bacteria". - Appl Environ Microbiol. 2019 Apr 15; 85(8): e02826-18
Peng, C., Bryce, C., Sundman, A., Kappler, A.
(See online at https://doi.org/10.1128/AEM.02826-18)
