Farshid Kafilzadeh, Razyeh Afrough, Habibollah Johari, Yaghoob Tahery
Lead (Pb) is one of the most widely heavy and toxic metal in the environment. Since it is used at the petroleum production, its abundance has been developed around the world. Application of the resistant bacteria to this toxic metal could be utilized in bioremediation process. The goal of this study is to isolate and characterize the leadresistant bacteria and evaluate their ability in lead bioremediation and evaluate their growth kinetic. Sampling was conducted from the soil around the three gas stations in Jahrom city. The amount of lead in the samples was measured by atomic absorption spectroscopy. The numbers of bacteria were counted at two medium with and without lead acetate. The isolation of bacteria was conducted by primary enrichment and then culturing on the nutrient agar with lead acetate. The bacteria were characterized by the common biochemical tests. The MIC test was utilized in order to obtain the minimum concentration lead essential for preventing bacteria growth. These bacteria were cultured in different concentrations of lead acetate on the LB broth medium in order to evaluate their growth kinetic. The logarithm average of the number of bacteria at the medium without lead was 6.605 and more than medium with lead. The maximum number of lead-resistant bacteria was 7.289 at station C, and the minimum number was 5.179 at the station A. The Bacillus sp, Pseudomonas sp, Corynebacterium sp, Staphylococcus sp and E.coli were isolated as the lead-resistant bacteria. Most of isolated bacteria from the soil of gas stations were highly capable to eliminate lead. Bacillus sp, Pseudomonas sp, Corynebacteriumsp, Staphylococcussp and E.coli eliminated 89.66% , 87.97 %, 86.64 %, 64.82 % and 60.35% of lead, respectively. The results of this study showed that Bacillus sp, Pseudomonas sp, Corynebacterium sp are highly resistant to lead and are sufficient options for lead bioremediation.
