Metal(loid)-resistant Bacillus megaterium H3 reduces arsenic uptake in rice (Oryza sativa Nanjing 5055) at different growth stages in arsenic-contaminated soil

Abstract Some metal(loid)-resistant bacteria play an important role in reducing metal(loid) accumulation by rice plants, however, little is known concerning the effect of arsenic (As)-resistant bacteria on the growth and As uptake of rice plants at different growth stages and the mechanisms involved. Here, we examined the effect of metal(loid)-resistant Bacillus megaterium H3 on As immobilization in solution and rice tissue As accumulation at different growth stages in exogenous As-polluted soils. The concentration of As decreased, while the pH values, cell growth, and cell-immobilized As significantly increased over time in the presence of strain H3. The As contents of the roots (7.4–68.6 mg kg−1) and above-ground tissues (2.1–6.6 mg kg−1) at the tillering, booting, and maturity stages, and the grains (0.16 mg kg−1) at the maturity stage decreased by 30–43%, 16–42%, and 33%, respectively in the H3 strain-inoculated soils compared with the controls. The available As content (0.21–0.30 mg kg−1) decreased by 36–43% in the H3 strain-inoculated soils at the booting and maturity stages of the rice plants compared with the controls. Moreover, strain H3 increased the As concentration (38–431 mg kg−1) by 30–86% in Fe plaque on the rice root surfaces compared with the controls. The results suggested that strain H3 reliably decreased the rice tissue As uptake by decreasing available As in soil and increasing rice root surface As adsorption. Our results may provide an effective As-resistant bacteria-assisted way for reducing the As accumulation to rice tissues in As-polluted soils.