ISOLATION AND IDENTIFICATION OF LEAD RESISTANT BACTERIA FROM WASTEWATER OF THREE PETROCHEMICAL COMPANIES IN BUSHEHR PROVINCE

Background and Aim:Lead is the most extensive heavy element in the environment. Resistant bacteria to this heavy metal are an approach in bioremediation. Isolation and identification of these resistant strains is the first step in bioremediation purposes. The aim of this study was to isolation and identification of lead-resistant bacteria and evaluation of their lead bioremediation potential.Methods:For this purpose, sampling was done from wastewater of three petrochemical companies in Bushehr. The samples were diluted and then cultured on Nutrient Agar medium containing 100ppm Lead nitrate. The tolerance of isolates was determined based on their MIC to lead and the most resistant strain was selected. The growth curve of the resistant strain at different concentrations of lead was obtained at 600 nm absorbance. The rate of lead removal was evaluated by Atomic Absorption analysis. Identification of the resistant bacteria was done by based on biochemical tests and sequencing of 16S rRNA gene.Results:The biochemical tests and sequencing results have confirmed the selected strain as Proteus mirabilis with 99% similarity. The MIC of lead for this isolate was 1500ppm and the removal rate of lead was measured as 94 % in the medium containing 100ppm.Conclusion:Based on these results it can be suggested that this isolate is a good candidate for further studies in bioremediation purposes for lead removal from contaminated environments.

Keywords:

Lead , Heavy Metals , Bioremediation