Feasibility of enhanced phytoextraction of Zn contaminated soil with Zn mobilizing and plant growth promoting endophytic bacteria

Three bacterial endophytes of Sedum alfredii, VI8L2, II8L4 and VI8R2, were examined for promoting soil Zn bioavailability and Zn accumulation in S. alfredii. Results showed that three strains were re-introduced into S. alfredii rhizosphere soils under Zn stress and resulted in better plant growth, as roots biomass increased from 80% to 525% and shoot biomass from 11% to 47% compared with the uninoculated ones. Strains IV8L2, II8L4 and IV8R2 significantly increased shoot and root Zn concentrations in the ZnCO3 contaminated soil. Inoculation with strain IV8L2 resulted in 44% and 39% higher shoot and root Zn concentrations, while strain IV8R2 significantly decreased shoot Zn concentration in the Zn3(PO4)2 contaminated soils. In the aged contaminated soil, isolates IV8L2, II8L4 and IV8R2 significantly increased root Zn concentration, but decreased shoot Zn concentration of Sedum alfredii. It suggested that endophytes might be used for enhancing phytoextraction efficiency.