Studies Of Isolation, Identification And Characteristics Of A Mercury-resistance Strain

The mercury usage is increasing currently and causing a large area of mercury pollution to our environment. And this pollution has threatened to the health of people. The mercury-removing strain was isolated from the soil polluted by mercury at a long time. The strain which had the largest and appropriate tolerance on Hg²⁺ was studied by identification （cell morphology, API20E and16SrDNA）, removal of Hg²⁺ and environmental conditions the gene which decided the strain to resist or remove mercury was by plasmid extraction and plasmid elimination. Better results were achieved. These research results laid a good foundation for the application of biotechnology of removal of mercury, which had great theoretical and practical significance.The specific findings are as follows:1. By ongoing picking and domestication, two mercury-resistance strains was isolated from contaminated soil. And the one which had a bigger tolerance on Hg²⁺ was selected for the study, which was named PII and could tolerance to the environment containing50mg L^-1Hg²⁺.2. By analysis of cell morphology, strain PII was Gram-negative and colonies of strain PII on LB solid medium were smooth, non-pigmented, and translucent after24hours of incubation at30°C. By analysis of the API20E system and the16SrDNA, PII was identified as Pseudomonas putida at last.3. The results of mercury-removing test results showed that the largest and appropriate tolerance of PII on Hg²⁺ was30mg L^-1 the highest Hg²⁺ removal of PII was85.2%at an initial concentration of15mg L^-1Hg²⁺.4. Environmental conditions could affect its growing and the removal rate of Hg²⁺ greatly, and the appropriate environmental conditions for PII to remove Hg²⁺ were the temperature for30℃, pH for7.0.5. Plasmids were extracted from PII, and its plasmid clips was4kb-5kb PII could not remove mercury any more after plasmid elimination so mercury removal capability of PII was related to plasmid the plasmid elimination tests showed that the gene which decided strain PII to resist and remove mercury was on the plasmid preliminarily.