Inhibition of perchlorate biodegradation by ferric and ferrous iron

Ilil Levakov, Jincheng Han, Zeev Ronen, Ofer Dahan

Research output: Contribution to journalArticlepeer-review


Previous observations from in-situ biological treatments in the subsurface of a perchlorate-contaminated site revealed multiple reduction processes occurring parallel to perchlorate degradation. Iron reduction was accelerated and correlated with a decline in the efficiency of the in-situ perchlorate reduction. In the current study, we examined the influence of iron forms on perchlorate reduction. A series of kinetic laboratory experiments were conducted, using an indigenous mixed perchlorate-reducing culture, enriched from the polluted soil that was undergoing bioremediation. The results show that ferrous iron was a non-competitive inhibitor with a 41% decrease in µmax for perchlorate reduction. Moreover, chlorate was accumulated in all samples treated with ferrous iron, indicating a disruption to the chlorate reduction step. Ferric iron, however, had less impact on perchlorate degradation with non-competitive inhibition reaching a 23% decrease in µmax. Scanning electron microscopy (SEM) revealed that the presence of ferrous iron in the perchlorate degradation enrichment culture initiated cell encrustation. We propose that during perchlorate reduction and the emission of oxygen from chlorite dismutation, the chemical oxidation of ferrous iron occurred near the bacteria's surface where the enzyme is located, forming an oxidized iron crust layer that can directly affect the perchlorate reduction enzymatic system.

Original languageAmerican English
Article number124555
JournalJournal of Hazardous Materials
StatePublished - 15 May 2021


  • Cell encrustation
  • Chlorate accumulation
  • Inhibition by iron
  • Non-competitive inhibition
  • Perchlorate biodegradation
  • Perchlorate kinetics
  • Perchlorate-reducing bacteria

All Science Journal Classification (ASJC) codes

  • Pollution
  • Waste Management and Disposal
  • Health, Toxicology and Mutagenesis
  • Environmental Engineering
  • Environmental Chemistry


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