Structure of microbial communities performing the simultaneous reduction of Fe(II)EDTA.NO2−and Fe(III)EDTA−

Kumaraswamy, Rajkumari; Kuenen, J Gijs; Kleerebezem, Robbert; van Loosdrecht, Mark C. M.; Muyzer, Gerard

Structure of microbial communities performing the simultaneous reduction of Fe(II)EDTA.NO2−and Fe(III)EDTA−

2006

Kumaraswamy, Rajkumari | Kuenen, J Gijs | Kleerebezem, Robbert | van Loosdrecht, Mark C. M. | Muyzer, Gerard

BioDeNOx is a combined physicochemical and biological process for the removal of nitrogen oxides (NOx) from flue gas. In the present study, two anaerobic bioreactors performing BioDeNOx were run consecutively (RUN-1 and RUN-2) at a dilution rate of 0.01 h⁻¹ with Fe(II)EDTA.NO²⁻ and Fe(III)EDTA⁻ as electron acceptors and ethanol as electron donor. The measured protein concentration of the reactor biomass of both runs was 120 mg/l. Different molecular methods were used to determine the identity and abundance of the bacterial populations in both bioreactors. Bacillus azotoformans strain KT-1 was recognized as a key player in Fe(II)EDTA.NO²⁻ reduction. PCR-denaturing gradient gel electrophoresis analysis of the reactor biomass showed a greater diversity in RUN-2 than in RUN-1. Enrichments of Fe(II)EDTA.NO²⁻ and Fe(III)EDTA⁻ reducers and activity assays were conducted using the biomass from RUN-2 as an inoculum. The results on substrate turnover, overall microbial diversity, and enrichments and finally activity assays confirmed that ethanol was used as electron donor for Fe(II)EDTA.NO²⁻ reduction. In addition, the Fe(III)EDTA⁻ reduction rate of the microbial community proved to be feasible enough to run the bioreactors, ruling out the chemical reduction of Fe(III)EDTA⁻ with sulfide as was proposed by other researchers.

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