Phytoremediation of cadmium-polluted soil by Chlorophytum laxum combined with chitosan-immobilized cadmium-resistant bacteria

This study examined the performance of the chitosan-immobilized cadmium-resistant bacteria Arthrobacter sp. and Micrococcus sp. on cadmium phytoremediation by Chlorophytum laxum in cadmium-polluted soil. These immobilized cadmium-resistant bacteria can survive in cadmium-contaminated soil and significantly increased soil cadmium solubility, but the ability of chitosan-immobilized cells to increase cadmium solubility was lower than that of free cells. A pot experiment demonstrated that chitosan-immobilized Micrococcus sp. promoted the growth of C. laxum planted in cadmium-contaminated soil. A significant increase in the cadmium concentration in the roots and aboveground parts of C. laxum was found in plants inoculated with free and chitosan-immobilized cells of these bacteria. The performance of Arthrobacter sp. free cells to augment cadmium accumulation in C. laxum was a little bit better than that of chitosan-immobilized Arthrobacter sp., except at 9 weeks after planting. The phytoextraction coefficient, bioaccumulation factor, and translocation factor of C. laxum inoculated with free and chitosan-immobilized cells of cadmium-resistant bacteria were higher than those of the uninoculated control and increased with time. Our findings suggest that chitosan-immobilized cells can be exploited to enhance the efficiency of cadmium phytoremediation by C. laxum.