Bacterial Oxidation and Stabilization of As(III) in Soil

摘要

The aim of this study was to find an arsenite-resistant bacterial strain, having high oxidizing capability from As(III) to As(V) in soil and stabilize the bio-available arsenic. An As(III) oxidizing bacteria strain XS3, was isolated from arsenic-rich gold mine tailings in Xinjiang, China. XS3 exhibits high resistance to As(III) and was able to oxidize up to 6,400mg/L in sucrose minimal salt low phosphate (SLP) medium, higher than any of the previous reported Pseudomonads. To determine the molecular basis of resistance and transformation aoxB/aioA gene encoding arsenite oxidases were amplified using a degenerate primer. The aioA gene was specific for the arsenite-oxidizing bacteria, and deduced amino acid sequence revealed 62% homology with Pseudomonas arsenicoxydans. Arsenite oxidase enzyme activity from this isolate displayed a high arsenite resistance level. Based on 16S rRNA gene sequence analysis XS3 was closely related to Pseudomonas sp. Strain XS3 showed potential for soil remediation by removing arsenite up to 62% in soluble exchangeable fraction (bio-available) from soil contaminated with 500mg/kg. Due to high resistance, efficient transforming ability and successful soil remediation, XS3 can be used as a potential candidate for soil bioremediation of As(III) contaminated sites.