2014; 47(4): 431-439

Published online August 31, 2014

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Characterization of Microbial Diversity of Metal-Reducing Bacteria Enriched from Groundwater and Reduction/Biomineralization of Iron and Manganese

Yumi Kim1, Jong-Min Oh1, Hea-Yeon Jung2, Seung Yeop Lee3 and Yul Roh1*

1Department of Earth and Environmental Sciences, Chonnam National University, Gwangju 500-757, Korea
2Korea Basic Science Institute, Gwangju 500-757, Korea
3Korea Atomic Energy Research Institute, Daejeon 305-353, Korea

Received: June 10, 2014; Revised: August 29, 2014; Accepted: August 31, 2014

Abstract

The purposes of this research were to investigate the enrichment of metal-reducing bacteria from KURT groundwater and the identification of the microbial diversity by 16S rRNA as well as to examine microbial Fe(III)/Mn(IV) reduction and to analyze morphological features of interactions between microbes and precipitates and their mineralogical composition. To cultivate metal-reducing bacteria from groundwater sampled at the KURT in S. Korea, different electron donors such as glucose, acetate, lactate, formate, pyruvate and Fe(III)-citrate as an electron accepter were added into growth media. The enriched culture was identified by 16S rRNA gene sequence analysis for the diversity of microbial species. The effect of electron donors (i.e., glucose, acetate, lactate, formate, pyruvate) and electron acceptors (i.e., akaganeite, manganese oxide) on microbial iron/manganese reduction and biomineralization were examined using the 1st enriched culture, respectively. SEM, EDX, and XRD analyses were used to determine morphological features, chemical composition of microbes and mineralogical characteristics of the iron and manganese minerals. Based on 16S rRNA gene analysis, the four species, Fusibacter, Desulfuromonas, Actinobacteria, Pseudomonas sp., from KURT groundwater were identified as anaerobic metal reducers and these microbes precipitated metals outside of cells in common. XRD and EDX analyses showed that Fe(III)-containing mineral, akaganeite (β-FeOOH), reduced into Fe(II)/Fe(III)-containing magnetite (Fe3O4) and Mn(IV)-containing manganese oxide (λ-MnO2) into Mn(II)-containing rhodochrosite (MnCO3) by the microbes. These results implicate that microbial metabolism and respiratory activities under anaerobic condition result in reduction and biomineralization of iron and manganese minerals. Therefore, the microbes cultivated from groundwater in KURT might play a major role to reduce various metals from highly toxic, mobile to less toxic, immobile.

Keywords metal-reducing bacteria, iron, manganese, biomineralization, groundwater

Article

2014; 47(4): 431-439

Published online August 31, 2014

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Characterization of Microbial Diversity of Metal-Reducing Bacteria Enriched from Groundwater and Reduction/Biomineralization of Iron and Manganese

Yumi Kim1, Jong-Min Oh1, Hea-Yeon Jung2, Seung Yeop Lee3 and Yul Roh1*

1Department of Earth and Environmental Sciences, Chonnam National University, Gwangju 500-757, Korea
2Korea Basic Science Institute, Gwangju 500-757, Korea
3Korea Atomic Energy Research Institute, Daejeon 305-353, Korea

Received: June 10, 2014; Revised: August 29, 2014; Accepted: August 31, 2014

Abstract

The purposes of this research were to investigate the enrichment of metal-reducing bacteria from KURT groundwater and the identification of the microbial diversity by 16S rRNA as well as to examine microbial Fe(III)/Mn(IV) reduction and to analyze morphological features of interactions between microbes and precipitates and their mineralogical composition. To cultivate metal-reducing bacteria from groundwater sampled at the KURT in S. Korea, different electron donors such as glucose, acetate, lactate, formate, pyruvate and Fe(III)-citrate as an electron accepter were added into growth media. The enriched culture was identified by 16S rRNA gene sequence analysis for the diversity of microbial species. The effect of electron donors (i.e., glucose, acetate, lactate, formate, pyruvate) and electron acceptors (i.e., akaganeite, manganese oxide) on microbial iron/manganese reduction and biomineralization were examined using the 1st enriched culture, respectively. SEM, EDX, and XRD analyses were used to determine morphological features, chemical composition of microbes and mineralogical characteristics of the iron and manganese minerals. Based on 16S rRNA gene analysis, the four species, Fusibacter, Desulfuromonas, Actinobacteria, Pseudomonas sp., from KURT groundwater were identified as anaerobic metal reducers and these microbes precipitated metals outside of cells in common. XRD and EDX analyses showed that Fe(III)-containing mineral, akaganeite (β-FeOOH), reduced into Fe(II)/Fe(III)-containing magnetite (Fe3O4) and Mn(IV)-containing manganese oxide (λ-MnO2) into Mn(II)-containing rhodochrosite (MnCO3) by the microbes. These results implicate that microbial metabolism and respiratory activities under anaerobic condition result in reduction and biomineralization of iron and manganese minerals. Therefore, the microbes cultivated from groundwater in KURT might play a major role to reduce various metals from highly toxic, mobile to less toxic, immobile.

Keywords metal-reducing bacteria, iron, manganese, biomineralization, groundwater

    KSEEG
    Apr 30, 2024 Vol.57 No.2, pp. 107~280

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