Dissolution of arsenic minerals mediated by dissimilatory arsenate reducing bacteria: estimation of the physiological potential for arsenic mobilization.

Drewniak Lukasz,Rajpert Liwia,Mantur Aleksandra,Sklodowska Aleksandra

doi:10.1155/2014/841892

Abstract

The aim of this study was characterization of the isolated dissimilatory arsenate reducing bacteria in the context of their potential for arsenic removal from primary arsenic minerals through reductive dissolution. Four strains, Shewanella sp. OM1, Pseudomonas sp. OM2, Aeromonas sp. OM4, and Serratia sp. OM17, capable of anaerobic growth with As (V) reduction, were isolated from microbial mats from an ancient gold mine. All of the isolated strains: (i) produced siderophores that promote dissolution of minerals, (ii) were resistant to dissolved arsenic compounds, (iii) were able to use the dissolved arsenates as the terminal electron acceptor, and (iii) were able to use copper minerals containing arsenic minerals (e.g., enargite) as a respiratory substrate. Based on the results obtained in this study, we postulate that arsenic can be released from some As-bearing polymetallic minerals (such as copper ore concentrates or middlings) under reductive conditions by dissimilatory arsenate reducers in indirect processes.

Highlights

Arsenic is considered to be one of the most hazardous elements, wherein its toxicity is revealed only when it is present in aqueous or gaseous form
We demonstrated that the isolated strains (i) produce metabolites that promote dissolution of minerals, (ii) are resistant to dissolved arsenic compounds, (iii) are able to use the dissolved arsenates as terminal electron acceptor, and (iv) are able to remove arsenic under anaerobic conditions from As-containing copper ore concentrates and middlings, in which copper minerals were used as the sole terminal electron acceptor
The mine waters and sediments contain high amounts of other heavy metals (e.g., Cu, Co, Mn, and Zn) and the microbial mats seemed to be an ideal source for the isolation of model dissimilatory arsenate reducing bacteria (DARB) that can be capable of dissolution of arsenic-bearing minerals

Summary

Introduction

Arsenic is considered to be one of the most hazardous elements, wherein its toxicity is revealed only when it is present in aqueous or gaseous form. Most of the arsenic-bearing minerals, such as arsenides and sulfarsenides, are considered nontoxic because they are highly insoluble. Problems arise when these primary minerals break down and enter into solution or form more soluble species such as oxides [1]. One of such cases, a common phenomenon in metallurgy industry, is arsenic release from ores and deposits into the environment through mining and smelting operations. Environmental problems are connected with the arsenic-bearing flotation tailings and mine waters. Arsenic present in these “reservoirs” can be transformed by the microbial activity and this may contribute to the further dissemination of arsenic contamination

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Conclusion