[BBC03-P08] Genomic and geochemical characterization of antimony-reducing microbial consortium obtained from mine tailing soil
Keywords:Antimony, Arsenic, bioreduction, dissimilatory Fe(III) reduction
Antimony (Sb) is a naturally occurring toxic element. Although the concentrations of Sb in soils are generally low, elevated levels of Sb have been released via mining and other anthropogenic activities. Antimony is commonly associated with arsenic (As) in the polluted environments, and both elements have similar chemistry and toxicity. Antimony and arsenic are mainly found in two oxidation states, trivalent (III) and pentavalent (V). The pentavalent form, Sb(V), is the stable species over a wide redox range and is often found to be strongly adsorbed with hydrous Fe(III) oxide in natural soils.
Although we have just began to unveil the full diversity of microbial-Sb interactions, microorganisms are likely to play important roles in Sb redox transformations in the environment. Recently, we have obtained various bacterial isolates and enrichment cultures capable of Sb transformations. In this study, we characterized Sb(V)-reducing anaerobic consortium by using physiological, geochemical, and genomic approaches. An anaerobic consortium was enriched from antimony mine tailing soil by its ability to reduce Sb(V) with lactate. As previously reported with a dissimilatory Sb(V)-reducing bacterium [1], the precipitation of Sb(III) as antimony trioxide was also confirmed in this consortium by X-ray absorption near-edge structure (XANES) analysis. In addition to Sb(V), other electron acceptors such as As(V), Fe(III) citrate, and anthraquinone-2,6-disulfonate (AQDS) were reduced in the presence of lactate. Microbial reduction of Fe(III) can release toxic metalloids bound to Fe(III) oxides, potentially influencing mobility of Sb and As in the contaminated soils. The ability of this consortium to utilize solid-state electrode as an electron donor was also indicated by using a bioelectrochemical system. Phylogenetic analysis of this consortium showed the predominant presence of Firmicutes and α-Proteobacteria-related populations. Draft genome sequence of this consortium was also determined. Majority of the sequences (>90%) were assigned to Firmicutes, and 79% of sequences belonged to the genus Desulfitobacterium. Functional genes associated with arsenic resistance, nitrate reduction, nitrogen fixation, polysulfide reductase, and putative reductive dehalogenase were found in the genome, indicating metabolic versatility of this consortium. Collectively, our study showed that the Sb(V)-reducing microbiota may influence mobility of Sb by direct reduction of Sb(V) and indirectly by the reduction of Fe(III), and its potential to facilitate bioremediation of other environmental pollutants indicated by the genomic content.
[1] Abin C.A., Hollibaugh J.T. Environ. Sci. Technol. 48, 681-688. (2014)
Although we have just began to unveil the full diversity of microbial-Sb interactions, microorganisms are likely to play important roles in Sb redox transformations in the environment. Recently, we have obtained various bacterial isolates and enrichment cultures capable of Sb transformations. In this study, we characterized Sb(V)-reducing anaerobic consortium by using physiological, geochemical, and genomic approaches. An anaerobic consortium was enriched from antimony mine tailing soil by its ability to reduce Sb(V) with lactate. As previously reported with a dissimilatory Sb(V)-reducing bacterium [1], the precipitation of Sb(III) as antimony trioxide was also confirmed in this consortium by X-ray absorption near-edge structure (XANES) analysis. In addition to Sb(V), other electron acceptors such as As(V), Fe(III) citrate, and anthraquinone-2,6-disulfonate (AQDS) were reduced in the presence of lactate. Microbial reduction of Fe(III) can release toxic metalloids bound to Fe(III) oxides, potentially influencing mobility of Sb and As in the contaminated soils. The ability of this consortium to utilize solid-state electrode as an electron donor was also indicated by using a bioelectrochemical system. Phylogenetic analysis of this consortium showed the predominant presence of Firmicutes and α-Proteobacteria-related populations. Draft genome sequence of this consortium was also determined. Majority of the sequences (>90%) were assigned to Firmicutes, and 79% of sequences belonged to the genus Desulfitobacterium. Functional genes associated with arsenic resistance, nitrate reduction, nitrogen fixation, polysulfide reductase, and putative reductive dehalogenase were found in the genome, indicating metabolic versatility of this consortium. Collectively, our study showed that the Sb(V)-reducing microbiota may influence mobility of Sb by direct reduction of Sb(V) and indirectly by the reduction of Fe(III), and its potential to facilitate bioremediation of other environmental pollutants indicated by the genomic content.
[1] Abin C.A., Hollibaugh J.T. Environ. Sci. Technol. 48, 681-688. (2014)