Soil microbial augmentation by an EGFP-tagged Pseudomonas putida X4 to reduce phytoavailable cadmium

In situ immobilization of heavy metals via physical, chemical, and biological processes presents practical remediation techniques for contaminated agricultural soils. In the current study, plant yield and cadmium (Cd) uptake by pakchoi ( Brassica chinensis L.) in relation to soil Cd fractionations were investigated to evaluate the remediating effect of EGFP-tagged Pseudomonas putida X4 in Cd-contaminated soil. The soil treated with various levels of Cd (0–10 mg kg −1 soil) was inoculated with P. putida X4:: gfp at an initial cell density of 10 7. Bacterial application transformed 7.5%–24.8% of soluble/exchangeable Cd mainly to the organic-bound fraction. Cd uptake decreased in pakchoi shoots by 10.0%–62.0% and pakchoi roots by 8.1%–60.1% after microbial remediation. The test bacterium was able to rapidly colonize the Cd-contaminated habitats and could persist at relatively stable cell densities during the whole pot experiments. This low cost and eco-friendly remediation method is very effective in the restoration of Cd-contaminated soils.