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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

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Background and objectives: Polyphenols can exert free radical scavenging effects by naturalizing dangerous reactive oxidants. Formation of reactive oxygen species can cause oxidative damage to human cells, leading to various diseases such as cancer, cardiovascular disease, osteoporosis and degenerative diseases. In this study, we investigated effect of treatment with various concentrations of lead (II) nitrate, a toxic and an oxidizing agent, on growth and biochemical parameters of alfalfa (Medicago sativa L.).
Methods: Total phenol content was estimated by the Folin-Ciocalteu method. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable free radical was used for assessment of free radical-scavenging activity. Changes in the activity of catalase and peroxidase as well as in the level of proteins, phenol content and malondialdehyde (as marker of lipid peroxidation) were investigated following treatment with different concentrations (0, 8, 12 and 16 mg/l) of lead nitrate for 21 days. All experiments were done in triplicate. Butylated hydroxytoluene and quercetin were used as standard controls.
Results: Treatment with lead significantly altered the level of total phenolic content, proteins, malondialdehyde and the activity of catalase and peroxidase (P<0.05).
Conclusion: Our results indicate that lead-contaminated soil can significantly alter biochemical and growth parameters of alfalfa.

 

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Background and objectives: Lead (Pb) is among the most toxic pollutants that affect health of both humans and animals. Finding a way to prevent Pb accumulation in animals’ bodies seems necessary. Bacterial cellulose nanofiber (BCNF) can remove heavy metals from aqueous solutions. This study investigates effects of oral consumption of BCNF, as a chelator, on Pb concentration in the kidney and liver tissues of rats.
Methods: Sixteen Wistar rats (aged 6-8 weeks) were divided into four groups: 1. control, 2. fed with Pb, 3. fed with Pb (50 μg/g) and BCNF (16 μg/g) simultaneously, and 4. fed with Pb and BCNF with 4 hours interval. The rats were euthanized, and the kidney and liver tissues were separated. After acidic digestion of the tissue samples, Pb concentration was measured by atomic absorption spectrometry.
Results: The mean concentration of Pb in the kidney and liver tissues of rats fed with Pb and BCNF were significantly lower than that of rats fed only with Pb. In addition, the mean Pb concentration in rats of group 3 was lower than that of group 4.
Conclusion: The results of this study showed the favorable effects of BCNF on prevention of Pb accumulation in the kidney and liver tissues of rats. Moreover, removal of Pb may be related to binding of BCNF with Pb in the gut or blood. More studies are necessary to determine the exact mechanisms through which BCNF can reduce Pb accumulation.