Bacteria-Mediated Arsenic Oxidation and Reduction in the Growth Media of Arsenic Hyperaccumulator Pteris vittata

摘要

Microbes play an important role in arsenic transformation and cycling in the environment. Microbial arsenic oxidation and reduction were demonstrated in the growth media of arsenic hyperaccumulator Pteris vittata L. All arsenite (AsⅢ) at 0.1 mM in the media was oxidized after 48 h incubation. Oxidation was largely inhibited by antibiotics, indicating that bacteria played a dominant role. To identify AsⅢ oxidizing bacteria, degenerate primers were used to amplify ～500 bp of the AsⅢ oxidase gene aioA (aroA) using DNA extracted from the media. One aioA (aroA)-like sequence (MG-1, tentatively identified as Acinetobacter sp.) was amplified, exhibiting 8296 and 91% identity in terms of gene and deduced protein sequence to those from Acinetobacter sp. 33. In addition, four bacterial strains with different arsenic tolerance were isolated and identified as Comamonas sp.C-1, Ftavobacterium sp. C-2, Staphylococcus sp. C-3, and Pseudomonas sp. C-4 using carbon utilization, fatty acid profiles, and/or sequencing 16s rRNA gene. These isolates exhibited dual capacity for both AsV reduction and AsⅢ oxidation under ambient conditions. Arsenic-resistant bacteria with strong AsⅢ oxidizing ability may have potential to improve bioremediation of AsⅢ-contaminated water using P. vittata and/or other biochemical strategies.