Shewanella sp. O23S as a Driving Agent of a System Utilizing Dissimilatory Arsenate-Reducing Bacteria Responsible for Self-Cleaning of Water Contaminated with Arsenic.

Lukasz Drewniak,Witold Uhrynowski,Robert Stasiuk,Aleksandra Sklodowska

doi:10.3390/ijms160714409

Lukasz Drewniak, Witold Uhrynowski + Show 2 more

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https://doi.org/10.3390/ijms160714409

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Abstract

The purpose of this study was a detailed characterization of Shewanella sp. O23S, a strain involved in arsenic transformation in ancient gold mine waters contaminated with arsenic and other heavy metals. Physiological analysis of Shewanella sp. O23S showed that it is a facultative anaerobe, capable of growth using arsenate, thiosulfate, nitrate, iron or manganite as a terminal electron acceptor, and lactate or citrate as an electron donor. The strain can grow under anaerobic conditions and utilize arsenate in the respiratory process in a broad range of temperatures (10–37 °C), pH (4–8), salinity (0%–2%), and the presence of heavy metals (Cd, Co, Cr, Cu, Mn, Mo, Se, V and Zn). Under reductive conditions this strain can simultaneously use arsenate and thiosulfate as electron acceptors and produce yellow arsenic (III) sulfide (As2S3) precipitate. Simulation of As-removal from water containing arsenate (2.5 mM) and thiosulfate (5 mM) showed 82.5% efficiency after 21 days of incubation at room temperature. Based on the obtained results, we have proposed a model of a microbially mediated system for self-cleaning of mine waters contaminated with arsenic, in which Shewanella sp. O23S is the main driving agent.

Highlights

Arsenic reduction may occur naturally in the environment as a result of the impact of physical and chemical factors or it can be caused by microorganisms capable of transforming arsenic compounds.Bacterial reduction of arsenate into arsenite may proceed by two different mechanisms
Phylogenetic analysis of the predicted dissimilatory arsenate reductase (ArrA) showed that the strain O23S is closely related with the well-characterized arsenate-respiring strain Shewanella sp
Based on the 16S rRNA and arrA gene amplicons analysis, this strain was found to be dominant in the microbial community in the Zloty Stok mine [7], it was used as a model organism representing dissimilatory arsenate-reducing bacteria (DARB)

Summary

Introduction

Arsenic reduction may occur naturally in the environment as a result of the impact of physical and chemical factors or it can be caused by microorganisms capable of transforming arsenic compounds.Bacterial reduction of arsenate into arsenite may proceed by two different mechanisms. In the second reduction process, called dissimilatory reduction, bacterial cells use arsenate as a terminal electron acceptor in the respiration process. Both reduction mechanisms constitute essential elements of the biogeochemical cycle of arsenic since they are responsible for the transformation of soluble As(V) compounds into more toxic and less mobile arsenites. Dissimilatory arsenate reduction is more prevalent in anoxic environments and most of the arsenate-respiring bacteria are obligatory anaerobes [1]. The role of microbial arsenic reduction in the homeostasis of this element in the environment depends on the physical and chemical conditions prevailing in the ecosystems, as well as on the structure of the microbial community involved in biogeochemical processes, such as dissolution and precipitation of (arsenic) minerals

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