| dc.description.abstract | Accroding to the industrial delopment, factories were rapidly built. Due to the neglect of management, heavy metal pollution occurred. Heavy metals, such as Cadmium (Cd), is toxic and non-degratable, which accumulate inside the human body resulting in disease. In our study, the surface display system Lpp-OmpA was fused to the metal-binding protein metallothionein to enhance bioremediation. After construction, the suitable condition for protein overexpression was evaluated. Western blot and green fluorescent protein were used to confirm the expression and folding of the target protein. In the cadmium sensitivity test, E. coli with pLM5 has higher resistance than other strains in 80 mg/L Cd2+. In the cadmium adsorption test, the adsorption capacity of the E. coli with pLM5 was 1.47 mg/g. Compared with the adsorption capacity of E. coli with pET-MTT5 (0.2585 mg/g), the adsorption capacity of E. coli with pLM5 has shown a 5.6-fold impovement. The result showed that outer membrane display stradegy was able to overcome the obstacles in cadmium adsorption. For increased initial Cd2+ concentrations of 2.5 - 80 mg/L, the adsorption capacity would increase, but the removal rate would drop from 54.8% to 24.6%. Otherwise, biosorption data of E. coli expressing pLM5 preferred to be simulated with Freundlich model. In Langmuir and Freundlich isotherm models, the correlation parameters for each model were shown. In the FTIR emission spectrum, the wavelengths of the N-H, C=O, and P=O bonding have shifted, indicating that these bonds are involved in the adsorption of Cd2+. In the mRNA gene expression analysis, the dnaK and clpB genes indicated the expression of LO-MTT5 may inhibit protein misfolding. In addition, the expression of czcB gene indicate that the presence of Cd2+ would induce the expression of cadmium efflux pump. Finally in the real wastewater test, the Cd2+ adsorption capacity of E. coli with pLM5 reached 20.5 mg/g within 48 hours. In conclusion, the outer membrane expression of metallothionein was shown as a potential techenique for recover industrial pollution. | en_US |