Phytoremediation Of Heavy Metal Polluted Soil Assisted By Microorganisms

The situation of soil pollution is universal all over the world.Phytoremediation had been paid much attention for which has the advantages of low cost and no harm to soil structure compared to the traditional technology just as physical and chemical remediation.Phytoremediation of polluted soil usually tightly with rhizoshperic microorganisms,so it becomes the hotpot to use plant and microorganisms to co-remediate the soil which polluted by heavy metals.The paper was to study the efficiency of use different microorganisms and plants to co-remediate the polluted soil.Two cadmium-resistant bacteria strains which could produce siderophore were isolated from the soil polluted by heavy metals,the bacterium were primarily identified as Bacillus sp(B1),Pseudomonus sp(B2) by observed it's configuration,and analyzed physiological and biochemical experiment results of the bacterium.The aggrandizement of microorganism to phytoremediation of Cd contaminated soil was conducted through inoculating the microorganism resistant to Cd in rape rhizosphere. The plant growth was promoted markly after inoculated by B2,and the biomass of plants were increased by 23.8%,42%,41.4% compared to non-treated control under different Cd pollution.The available content of Cd in soil was 9.4mg/kg and 16.8mg/kg,which were much higher than control, 6.5mg/kg and 12.7mg/kg,it's could be concluded that B2 had the ability to mobilize Cd in soil.The Cd concentration in shoots and roots was also remarkly increased by the inoculation of B2,the Cd concentration of shoot and root were increase by 15%,8% compared to the control when the Cd concentration of soil was 50mg/kg,and increase by 20%,14% compared to the control when the Cd concentration of soil was 100mg/kg.B1 had no remarkly effect on rape biomass and the available content of Cd in soil.The Cd concentration in root was higher than control,and the transfer ratio from root to shoot was 0.54 that little lower than control which was 0.58,but the total Cd content of shoot was significantly higher than control.A sand culture experiment was conducted to investigate the effect of arbuscular mycorrhizal fungi(Glomus mosseae,G)and rhizobium(Rhizobium meliloti,R) on lead uptake and translocation in Medicago sativa L.Under the same lead level, dually inoculation(AM fungus plus rhizobium) significantly enhanced the plant biomass, mycorrhizal colonization and the cotent of N,P than non-inoculated plants.Increasing Pb level reduced plant biomass,mycorrhizal and content of N,P,but had no significantly influence of dually inoculated plants,and mycorrhizae stimulated plants nodulation.Coinoculation of AM fungus plus rhizobium increased shoot biomass over single mycorrhizal plants by 19%(at 0 mg/L),17.8%(at 200 mg/L),22%(at 400 mg/L). Coinoculation decreased the Pb concentration in shoot,large part of Pb were concentrated in root and reduced Pb translocation from root to shoot,alleviated the Pb toxicity to plants,but coinoculation signficantly enhanced the content of Pb than non-inoculated plants,it's correlated with the larger biomass of plants.