A Novel Autotrophic Bacterium Isolated from an Engineered Wetland System Links Nitrate-Coupled Iron Oxidation to the Removal of As, Zn and S

Mattes, Al; Gould, Douglas; Taupp, Marcus; Glasauer, Susan

A Novel Autotrophic Bacterium Isolated from an Engineered Wetland System Links Nitrate-Coupled Iron Oxidation to the Removal of As, Zn and S

2013

Mattes, Al | Gould, Douglas | Taupp, Marcus | Glasauer, Susan

A neutrophilic, autotrophic bacterium that couples iron oxidation to nitrate reduction (iron-oxidizing bacteria [IOB]) under anoxic conditions was isolated from a working bioremediation site in Trail, British Columbia. The site was designed and developed primarily to treat high concentrations of Zn and As that originate from capped industrial landfill sites. The system consisted of two upflow biochemical reactor cells (BCR) followed by three vegetated wetland polishing cells with sub-surface flow and a holding pond. During a 5-year period (2003–2007), the system treated more than 19,100 m³ of contaminated water, removing and sequestering more than 10,700 kg of As, Zn and sulfate at average input water concentrations of: As, 58.6 mg l⁻¹ (±39.9 mg l⁻¹); Zn, 51.9 mg l⁻¹ (±35.4 mg l⁻¹) and SO₄ ²⁻, 781.5 mg l⁻¹ (±287.8 mg l⁻¹). The bacterium was isolated in order to better understand the mechanisms underlying the consistent As removal that took place in the system. Analysis using Basic Local Alignment Search Tool (BLAST) database showed that the closest homologies are to Candidatus accumulibacterphosphatis (95 % homology), Dechloromonas aromatica (94 %), and Sideroxydans lithotrophicus ES-1 (92 %) Within the BCR cells, the IOB oxidized Fe²⁺ generated by iron-reducing bacteria (IRB); the source of the iron was most likely biosolids and coatings of iron oxide on locally available sand used in the matrix. We have provisionally designated the novel bacterium as TR1.

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