---

Abstract Background and Objective: the plants with the less side effects and drug resistance have been used worldwide. In this study, we compared the inhibitory effects of nanocopper and essential oil of Melissa officinalisL.a on E.coli and S.mutans in In Vitro condition. Material and Methods: for studying diameter of inhibitory zone, disk agar diffusion method was used. Then, antibacterial effects of these substances were evaluated by treating them for 24 hours in Nanocopper particles (concentration of 100 and 500 ppm) and essential oil (12.5% to 100%), and analyzed by ANOVA. Results: twenty-four hours after treatment, nanocopper had no inhibitory effect on these bacteria. However, the diameter of inhibitory zone for E.coli and S.mutans was 31.30±0.13mm and 16.30±0.13mm, respectively. There was not any synergistic effect between different concentrations of this plant and 500ppm of nanocopper after 24 hours of treatment on E.coli. But for S. Mutans, the diameter of inhibitory zone for mixture of 50% & 25% essential oil and 500ppm concentration of nanocupper was increased significantly compared to only essential oil (p=0.001,p=0.01). Conclusion: based on the findings, nanocopper particles and essential oil of Melissa officinalis L.a have not any synergic effects on E.coli, but with some concentrations of this plant the reverse is true on S.mutans. Keywords: Essential Oil of Melissa Officinalis, Nanocopper Particles, E.Coli, S.Mutans

---

Abstract Background and Objectives: Contamination of environment to lead and copper is rising due to human activities. One of the best methods to remove heavy metals from the environment is bacterial remediation. This study aimed to isolate bacteria and investigate the mechanism of lead and copper bioremediation. Material and Methods: Heavy metal resistant bacteria were isolated from contaminated wastewater samples. The isolates with high resistance to lead and copper were selected for further studies and bioremediation was assessed by atomic absorption spectrophotometer. To determine the functional groups to remove metals, FT-IR was employed. In addition, plasmid curing was studied to determine the location of the genes that are resistance to heavy metals. Results: Ten bacterial isolates that are resistance to heavy metals were isolated. Among these, MKH3 with the highest remediation activity removed %90 lead and %92 copper from the growth medium. The absorption mechanism of MKH3 indicated that the functional groups such as carboxyl, amide, carbonyl and hydroxyl were most effective for removal of heavy metals from the growth medium. The results revealed that heavy metal resistant genes may be located on plasmid DNA. Furthermore, molecular identification demonstrated that MKH3 was similar to Enterobacterhormaechei with 98% homology. Conclusion: Bacterium isolated from a contaminated site showed the ability to remove a high amount of lead and copper. Thus, MKH3 could be useful for the bioremediation of heavy metals, particularly lead and copper, from industrial wastewater and contaminated sites. Keywords: Biosorption, Bacteria, Lead, Copper, FT-IR