| dc.description.abstract | Bioaccumulation and biosorption are two important mechanisms for some microorganisms to resist heavy metals, which makes bacteria a potential bioremediation tool. In an attempt to enhance the bioaccumulation capacity of Pseudomonas sp. A46 strain, we cloned the gene of metallothionein into Pseudomonas sp. A46. We developed a genetic bacteria with counter selection system that can be used in Pseudomonas sp. A46. After removing the upp gene, the gene fragment that expresses the fusion protein. Thereafter, the minimum inhibitory concentrations (MIC) for the heavy metal copper and cadmium were determined for A46, M01(MT1 expressed by chromosome) and pJBME (expressed MT1 by plasmid). The MIC of copper was 250 ppm and the cadmium was 20 ppm. With these MIC values, the resistance of the genetic strain to heavy metals was not increased. In the copper and cadmium bioaccumulation assay, there was no significant difference among A46, M01, and pJBME, suggesting that metallothionein may not increase the bioaccumulation capacity. In the EDTA leaching test for the biosorption of heavy metals, most of the copper was found to accumulate in the interior of the cells. The bioaccumulation of this bacterium was a key player. However, the overall removal rate was only 2%. n the other hand, most of the cadmium was adsorbed extracellularly, and the overall removal rate was 35%, indicating that the bacterium bioremediate cadmium via biosorption, and the biofilm production was helpful in adsorbing cadmium and protecting the strain. Although metallothionein cannot increase the bioaccumulation capacity of this strain, this strain of bacteria has a strong biosorption capacity for cadmium. | en_US |