| Summary: | Arsenic causes human health problems after accumulate in the body for 10-15 years and arsenite [As(III)] is generally regarded as being more mobile and toxic than other oxidation states. In this study, two-hundred and three bacterial strains were isolated from groundwater and soil samples collecting in Ubon Ratchathani Province, Thailand. All strains were screened for arsenic tolerant efficiency at 1-10 mM of sodium arsenite. Eighteen selected strains which had the highest resistance to 10 mM of As(III) were further studied for their As(III)-oxidizing activity and growth in enrichment and growth medium (EG medium) supplemented with 0.58 mM of As(III). It was found that strain PNKP-S2 was able to grow in the medium with As(III) as a sole energy source and had 89.11% As(III) removal within 48 h. The PCR-based 16S rDNA sequencing analysis revealed that the strain PNKP-S2 was closed relative to Bacillus sp. This is the first report on Bacillus sp. chemolithoautotrophic As(III)-oxidizer and this strain could be a potential candidate for application in arsenic remediation of contaminated water.
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