Arsenic hyperaccumulator Pteris vittata L (Chinese Brake fern) may accumulate up to 2.3% As in its biomass, making it a viable candidate for phytoremediation of arsenic contaminated sites. P. vittata is capable of extracting As from both soluble and insoluble forms. Arsenic uptake mainly occurs via the roots so soil rhizosphere characteristics significantly affect plant As accumulation. The availability of plant nutrients and As are impacted by the microbial community in the rhizosphere of P. vittata, including plant growth promoting rhizobacteria (PGPR). Seven As-resistant bacteria (ARB; tolerant up to 10 mM AsV) from 3 genera were isolated from the rhizosphere soils.  They were fluorescent under ultraviolet illumination, suggesting the presence of siderophores. They were efficient in solubilizing arsenic from FeAsO₄ (from 2.58 to 2.89 mg/L) and AlAsO₄ minerals (from 5.04 to 7.37 mg/L) and enhanced plant arsenic uptake (from 18.1 to 35.3 and 21.9 to 236 mg/kg in the fronds) respectively in a hydroponic system. In addition, ARB increased the roots biomass from 2.2 to 4.2 (FeAsO₄) and 1.5 to 3.4 (AlAsO₄) g dw/plant in P. vittata after 7 d of growth.  Production of siderophores by ARB may be responsible for Fe solubilization. In contaminated sites PGPR can aid plant growth and enhance phytoextraction of arsenic-contaminated soil.

Keywords: P. vittata rhizosphere, Arsenic resistant PGPR, As solubilization.