Bioaugmentation with As-transforming bacteria improves arsenic availability and uptake by the hyperaccumulator plant (L).

Inorganic arsenic (As) is a toxic and carcinogenic pollutant that has long-term impacts on environmental quality and human health. plants hyperaccumulate As from soils. Soil bacteria are critical for As-uptake by . We examined the use of taxonomically diverse soil bacteria to modulate As speciation in soil and their effect on As-uptake by . Aqueous media inoculated with MK800041, MK344656, MK345459, MK346993 or MK346997 resulted in the oxidation of 5-30% As(III) and a 49-79% reduction of As(V). Soil inoculated with increased extractable As(III) and As(V) from 0.5 and 0.09 in controls to 0.9 and 0.39 mg As kg soil dry weight, respectively. Moreover, and plants inoculated with , , strains, and strains MK344655, MK346994, MK346997, significantly increased As-uptake by 43, 32, 12, 18, 16, and 14%, respectively, compared to controls. The greatest As-accumulation (1.9 ± 0.04 g kg frond Dwt) and bioconcentration factor (16.3 ± 0.35) was achieved in plants inoculated with . Our findings indicate that the tested bacterial strains can increase As-availability in soils, thus enhancing As-accumulation by . , a well-known As-hyperaccumulator, has the remarkable ability to accumulate higher levels of As in their above-ground biomass. The As-tolerant bacteria-plant interactions play a significant role in bioremediation by mediating As-redox and controlling As-availability and uptake by . Our studies indicated that most of the tested bacterial strains isolated from As-impacted soil significantly enhanced As-uptake by . oxidized 20% of As(III) and reduced 50% of As(V), increased As-extraction from soils, and increased As-uptake by 43% greater compared with control. Therefore, these strains associated with can be used in large-scale field applications to remediate As-contaminated soil.