| In order to explore the application value of microorganisms in Cd,As composite contaminated soil.In the laboratory,the micro-organisms resistant to Cd and As were selected and identified by traditional separation method,and used in potted experiments to explore its influence on Cd and As forms in soil and the changes in the content of Cd and As in various parts of rice.The main results are as follows:(1)Isolate and purify from contaminated soil to obtain well-grown strains XC3 and XC6 with high adsorption rate for Cd and As.The XC3 strain is identified as Janibacter sp.It was identified as Bacillus licheniformis(Bacillus licheniformis)with the gene accession number MK775012.Both XC3 and XC6 belong to the Bacillus family.Compared with the two strains,XC3 has a better adsorption effect on As and XC6 has a better adsorption effect on Cd.The optimal growth condition of strain XC3 is p H=5,temperature is 30??inoculation volume is 10%;the optimal growth condition of strain XC6 is p H=6,temperature is 30??inoculation volume is 10%.At p H=7,incubation time of 48h,and temperature of 25-30??strains XC3 and XC6 had the best adsorption effect when the Cd and As concentrations were less than 10mg·L-1,and the Cd adsorption rates reached45.39%and 57.31,respectively.%And As adsorption rates reached 61.93%and 54.31%,respectively.(2)XC3 bacteria suspension diluted 100 times and XC6 bacteria suspension diluted 10 times had the best effect on promoting the germination of rice seeds.Adding different volumes of bacteria solution in the soil cultivation test can reduce the content of weak acid soluble Cd and exchangeable As in the soil,and increase the content of residual Cd and residual As.Adding 40m L of XC6 has the best effect on reducing the weak acid soluble Cd in the soil,which is reduced by 16.21%;adding 40m L of XC3 has the best effect on reducing the exchangeable As,which is reduced by 1.19%.(3)Each treatment in the pot experiment can reduce the Cd and As content of rice parts and grains.The strain XC6treatment has the best Cd reduction effect,and the strain XC3 treatment has the best As reduction effect.Both active and inactivated bacterial solutions can reduce the content of weak acid soluble Cd and exchangeable As in the soil,and increase the content of residual Cd and residual As.Exogenous addition of microorganisms can change the soil microbial community structure.Each treatment of adding Cd and As microorganisms to early and late rice can increase the yield of rice.XC3 cells have the best yield-increasing effect.Compared with the blank group,the addition of inactivated cells XC3 in early rice increases by60.18%,and in late rice.The number of viable cells XC3 increased by 99.47%.The addition of inactivated bacteria has a greater effect on the Cd and As contents of early rice,and the inactivated XC6 has the best effect on Cd,which can reduce the Cd content in rice roots,stems,leaves and rice compared with the blank group by 39.27,34.18,27.93,52.41%;Inactivated XC3 has the best effect on As,which can reduce the As content in rice roots,stems,leaves and rice compared with the blank group by 35.42,52.10,57.83,51,60%,respectively.The treatment with live cells added had a greater effect on the Cd and As contents in various parts of late rice.Huo XC6 had the best effect on Cd,which could reduce the Cd contents in rice roots,stems,leaves and rice compared with the blank group by 45.46,47.34,48.24,57.78%;Huo XC3 had the best effect on As,which could reduce the As content in rice root,stem,leaf,and rice compared with the blank group by 40.78,59.24,60.61,56.54% respectively. |
PDF Full Text Request