Effects On Endophytic Cadmium-Resistant Bacteria To Phytoremediation Of Cadmium Pollution In Artemisia Selengensis

Artemisia seleniumgensis, a hyperaccumulator that has strong accumulation capacity of cadmium, has great importance of repairing cadmium pollution in the Donting Lake area because of its high rhizome transfer coefficient. Endogenous cadmium-resistant bacteria have high tolerance to cadmium. It can also secrete growth hormone and other similar substances, and thus promote plant growth and improve resilience to environment. This research selects an endogenous cadmium-resistant strain, Artemisia seleniumgensis that colonize in the Donting Lake area, as a model strain by screening multiple performance indicators. By measuring plant growth, physiological paramenters, amount of cadmium accumulation, rhizome transfer coefficient and antioxidant effects of Artemisia selengensis under cadmium treatment, this research studies the strengthen effect that endogenous cadmium-resistant bacteria have on repairing cadmium-polluted environment by Artemisia selengensis. This study also proves the feasibility of establishing plant-endophytes joint bioremediation system to strengthen phytoremediation. The following conclusions are drawn through a series of experiments:1. Ten endophytes were successfully separated from the hyper-accumulating plant Artemisia seleniumgensis. C2, endophyte with excellent resistance, was isolated through heavy metal resistance and other indicators screening process. Through the morphological, physiological and biochemical characteristics analysis and sequence analysis of the target endophyte C2, it was identified as Pseudomonas fluorescencs.2. Endophyte C2 has significant impact on plant growth of Artemisia selengensis, yet little influences on the adsorption capacity and transport capacity of cadmium. Under the effect of C2 strains and in the cadmium-polluted environment, Artemisia selengensis can not only grow normally, but also promote the ability to accumulate cadmium by root growth. Although endophyte vaccination does not significantly alter the adsorption capacity and transport capacity of cadmium, it does increase the biomass of Artemisia selengensis, and thus enhance the amount of cadmium extraction from individual plant.3. Endogenous cadmium-resistant bacteria have important influence on rhizosphere soil microbial activity. Under the effect of C2, the soil changes from fungus type into bacterial type. The number of rhizosphere soil microbes increases significantly. Soil microbial biomass carbon and biomass nitrogen also has been improved.This research successfully separated and identified endogenous cadmium-resistant bacteria C2 from Artemisia selengensis. By studying C2’s impact on Artemisia selengensis, it concludes that endogenous cadmium-resistant bacteria can enhance the effects of Artemisia selengensis phytoremediation of cadmium pollution. This also provides theoretical basis for further study and establishment of plant-endophytes joint bioremediation system.