Screening Of Cadmium-tolerant Fungi And Their Remediation Of Cadmium Contaminated Soil

"Cadmium pollution"has become a global environmental problem,causing the great harm to human health.The problem of soil contaminated by heavy metal cadmium is increasingly serious,and the use of microbial remediation has a low cost and no secondary pollution,which has a good application prospect.Screening the Cadmium-tolerant fungi not only can adapt to soils with high cadmium content,but also adsorb the heavy metal cadmium.It provides a useful bacterial strain for the remediation of cadmium contaminated soil.In this study,we collected some soil samples from cadmium contaminated areas,and screened cadmium tolerant fungi from the soil samples.We identified the best one from many Cadmium-tolerant fungi.We also studied its cadmium adsorption capacity,tolerance to heavy metal cadmium,growth conditions and effects on rice growth.?1?screening and identification of cadmium resistant fungi:Cd²⁺concentration domestication method was used to isolate and screen cadmium resistant fungi from the cadmium contaminated soil collected.Finally,We obtained a fungus which can have a tolerance of 20 mg/kg cadmium.we also named the fungus JM17 and identified the fungus.Based on the morphological characteristics and DNA sequence analysis,aspergillus sp.We identified the fungus belongs to aspergillus sp.?2?We research the cadmium adsorption capacity of JM17,its response to cadmium stress,and the effects of temperature and pH on the growth and cadmium tolerance of JM17.It was found that the adsorption rate of Cd by the addition of mycelia was gradually not obvious,and reached the maximum value of 55%and 77%when the addition amount was 1.2g.The higher the concentration of Cd was,the greater influence on the growth of the strain was.When the concentration of Cd reached 20mg/kg,the diameter of the colony was only 1.5cm.JM17 can grow in the temperature of 24 to 36?.When the pH is between 4.0 to 8.0JM17 also grow.For JM17,the best pH and temperature is 4.0 and 30?.Neither temperature nor pH affected the cadmium tolerance of JM17.?3?We make the restorative agent using JM17,attapulgite,mushroom residue,potato and other fermented materials.The experiment of rice pot cultivation was carried out to determine the effect of cadmium restorer.The germination rate and plant height of rice in the experimental group were higher than those in the control group.The cadmium content in stem leaf and root of rice was lower in the experimental group than in the control group.The heavy metal content in soil in the experimental group was higher than that in the control group,which fully demonstrated that the remediation agent had the effect of inhibiting the migration of Cd from soil to rice,and reduced the content of Cd in rice plants.?4?The Cadmium-tolerant fungi which was screened from cadmium contaminated paddy fields havs the potential to adapt to the special environment of cadmium contaminated soil.The fungi had strong cadmium tolerance and adsorption capacity.And its requirement for growth condition is simple.So it is convenient for mass cultivation.Cadmium tolerant fungi not only is harmless to rice,but also can promote the growth and reduce the stress of the growth and development of rice.