Cadmium Removal from Water and Soil by a Cadmium-Resistant Rhizobacterium and Its Effect on Plant Root Elongation

Abstract

A cadmium resistant rhizobacterium, Pseudomonas sp. PM2, was isolated from plant roots. It is highly resistant to cadmium toxicity. The minimum inhibitory concentrations of cadmium for Pseudomonas sp. PM2 is 2100 mg/L. Pseudomonas sp. PM2 produced high levels of siderophore and rhamnolipid biosurfactant in 74.88 µM of deferoxamine mesylate equivalents and 329.54 mg/L, respectively. It was able to remove cadmium ion in an aqueous solution by 69.84% at the initial cadmium ion concentration of 25 mg/L. Pseudomonas sp. PM2 significantly increased cadmium bioavailability in contaminated soil by increasing DTPA-extractable cadmium concentration or a bioavailable form of cadmium. The increase in cadmium bioavailability in soil helps to promote cadmium uptake by plants for cadmium phytoextraction. In addition, Pseudomonas sp. PM2 had no positive or negative effects on seed germination and root elongation of Glycine max L. under the absence and presence of cadmium. Our findings suggest that Pseudomonas sp. PM2 could be useful in the further development of biological treatment of cadmium in contaminated water and soil.

Keywords

• cadmium
• siderophore
• biosurfactant
• Pseudomonas sp.
• Glycine max L.