Abstract
A new facultative chemolithoautotrophic arsenite (AsIII)-oxidizing bacterium TCC9-4 was isolated from a hot spring microbial mat in Tengchong of Yunnan, China. This strain could grow with AsIII as an energy source, CO2–HCO3- as a carbon source and oxygen as the electron acceptor in a minimal salts medium. Under chemolithoautotrophic conditions, more than 90% of 100 mg/L AsIII could be oxidized by the strain TCC9-4 in 36 h. Temperature was an important environmental factor that strongly influenced the AsIII oxidation rate and AsIII oxidase (Aio) activity; the highest Aio activity was found at the temperature of 40∘C. Addition of 0.01% yeast extract enhanced the growth significantly, but delayed the AsIII oxidation. On the basis of 16S rRNA phylogenetic sequence analysis, strain TCC9-4 was identified as Anoxybacillus flavithermus. To our best knowledge, this is the first report of arsenic (As) oxidation by A. flavithermus. The Aio gene in TCC9-4 might be quite novel relative to currently known gene sequences. The results of this study expand our current understanding of microbially mediated As oxidation in hot springs.
Highlights
Geothermal waters often contain high levels of arsenic (As) and may contribute to surface and ground water contaminations (Langner et al, 2001; Zhang et al, 2008)
When potential carbon sources and inorganic substrates were tested, the strain was cultured in minimal salt medium (MSM), and the concentrations of carbon sources and inorganic substrates added to the medium were 10 mM
The aioA gene of environmental samples was amplified with degenerate primers aroA95f (5 TGYCABTWCTGCAIYGYIGG 3 ) and aroA599r (5 TCDGARTTGTASGCIGGICKRTT 3 ; Hamamura et al, 2009) in a 25 μL PCR mixture consisting of PCR Ex Taq buffer, 100 μmol dNTP mixtures, 0.5 μmol primers, 50 ng templates, and 1 U of Ex Taq DNA polymerase (TaKaRa, Japan)
Summary
Received: 02 March 2015 Paper pending published: 19 March 2015 Accepted: 09 April 2015 Published: 06 May 2015. A new facultative chemolithoautotrophic arsenite (AsIII)-oxidizing bacterium TCC9-4 was isolated from a hot spring microbial mat in Tengchong of Yunnan, China. This strain could grow with AsIII as an energy source, CO2–HCO3− as a carbon source and oxygen as the electron acceptor in a minimal salts medium. More than 90% of 100 mg/L AsIII could be oxidized by the strain TCC9-4 in 36 h. On the basis of 16S rRNA phylogenetic sequence analysis, strain TCC9-4 was identified as Anoxybacillus flavithermus. This is the first report of arsenic (As) oxidation by A. flavithermus. The results of this study expand our current understanding of microbially mediated As oxidation in hot springs
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