Enhancing Remediation And Preliminary Mechanism Of Sedum Plumbizincicola Inoculated With Trichoderma In Cadmium Contaminated Soils

Phytoextraction of Cd-contaminated soils with hyperaccumulating plants is considered to be an environmental friendly remediation technology. However, the application of phytoextraction is always limited because of the low biomass and slow growth of hyperaccumulating plants. Therefore, the development of new technologies, for example, combined remediation method of hyperaccumulator inoculated with microorganism are consider more and more.In the present study, the biological character of T. reesei FS10-C, scanned from a multi-metals contaminated soil, and its reinforcement on phytoextration with hyperaccumulator Sedum plumbizincicola were investigated. The results were summarised as follows.1. T. reesei FS10-C can tolerate high concentration of Cd, and the EC50of Cd to the strain in solution is32.0mg/kg. The results from electron microscopy indicated that no significant structural change was found at10mg/L of Cd treatment, while visible symptoms of stress were observed under higher Cd concentrations, i.e. crimple and rupture of cell structure, inhibition the production of cytochrome and spore, and reproduction with mycelium segments.2. In solution culture the adsorption amount of Cd2+is positively correlative to the dry biomass of this strain (r=0.9072,p<0.05), and the adsorption of Cd on the surface of cells raised the concentration S, which might be due to release of damage from Cd stress. With the increasing of Cd stress, the activation of Cd increased. In addition, T. reesei FS10-C showed the ability to dissolve CdCO3in solution culture. With the increasing of Cd stress, the activation of Cd increased.3. In artificial contamination soils, the shoots of S.plumbizincicola resulted a17.1%-42.5%increase in dry weight with the treatment of T. reesei FS10-C, respectively (P<0.5). Meanwhile, the strain significantly improved Cd uptake. Compared with the non-inoculated plants it was increased by46.2%in soils contaminated with15mg/kg Cd. Otherwise, total microbial biomass carbon and available P of soils were higher than the control. Nevertheless, the application of T. reesei FS10-C fermentation exhibited little effects on Cd concentration of shoots, soil pH, or NH4OAc-extractable Cd concentration. However, it was revealed that T.reesei FS10-C has the ability to enhance remediation of Cd-conraminated soils by S.plumbizincicola.4. T.reesei FS10-C preparation inoculated on the surface of the multi-metal contaminated soils promoted the growth and shoots Cd concentration of hyperaccumulator S. plumbizincicola. The rate of Cd extraction from soils by plant shoot was up to37.6%, which was1.5times more than control. Meanwhile, the application of T.reesei FS10-C preparation increased the soil microbial biomass carbon which improved soil ecological properties. Otherwise, the concentration of available P in soils and P concentration of shoots were higher than control. In conclusion, T.reesei FS10-C agent has enormous applied potential in enhancement remediation of Cd-contaminated soils by S. plumbizincicola.