Immobilization of cadmium by immobilized Alishewanella sp WH16-1 with alginate-lotus seed pods in pot experiments of Cd-contaminated paddy soil

This study prepared immobilized Alishewanella sp. WH16-1 using alginate and lotus seed pods as a matrix and investigated the effects of its immobilization on Cd2+ in a culture solution and in soil. Compared with the free WH16-1 strain, the immobilized WH16-1 strain possessed greater stability for long-term use and storage and higher removal ability for Cd2+ in the culture solution. A model of Cd2+ removal by the immobilized WH16-1 strain was proposed. The immobilized WH16-1 strain was incubated in the pot experiments of Cd-contaminated paddy soil for 120 days, and the pot experiments of Cd-contaminated paddy soil without the immobilized WH16-1 strain were used as a control. Compared with the control, the exchangeable and carbonate-bound Cd in the paddy soil incubated with the immobilized WH16-1 strain significantly decreased by 33.6% (P < 0.05) and 17.36%, respectively, and the Cd concentrations in the rice significantly decreased by 78.31% (P < 0.05). The results indicate that alginate-lotus seed pods can be used as excellent cost-effective cell carriers for the immobilization of Alishewanella sp. WH16-1 and that the immobilized WH16-1 strain may be applicable for the biological stabilization of Cd in Cd-contaminated paddy soil.