Isolation of heavy metal resistant Acidovorax sp. from agricultural soil and optimization of metal biosorption
Subject Areas : Environmental Microbiology
1 - Assistant Professor, Department of Biology, Islamic Azad University, Islamshahr branch, Islamshahr, Iran
Keywords: heavy metals, Biosorption, Polluted soils, Acidovorax sp,
Abstract :
Background & Objectives: Bioremediation is the most efficient method for removal of heavy metals from contaminated soils. The aim of this study was the isolation of heavy metal resistant bacteria and optimization of removal conditions. Material & Methods: In this cross sectional study, sampling was carried out from agricultural soils of different areas of Islamshahr. Screening of resistant strains was carried out in medium containing 1 mM of metals including cadmium, zinc, and copper. The minimum inhibitory concentration (MIC) of metals was investigated by agar dilution method. Metal removal was carried out by atomic absorption spectroscopy. Various removal parameters such as pH, initial metal concentration, as well as contact time were investigated. Identification of strains was performed based on 16S rRNA gene sequences. Results: Among all 100 bacterial isolates, BRH3 was resistant to all 3 metals. The MIC of copper, cadmium, and zinc were 3 mM, 2 mM, and 3 mM, respectively. The isolate was able to remove 32.5%, 47.0%, and 56.8% of Cu, Cd, and Zn, respectively. The maximum biosorption of zinc and cadmium were obtained 69%, and 59% at pH 6, contact time of 4 hours, and an initial metal concentration of 150 mg/L. The maximum biosorption for copper was 48% in the same condition, except for optimal pH which was 5. The isolate was called as Acidovorax sp. HM_AH 13, and was deposited as JN676128 in GenBank. Conclusion: Results showed that heavy metal resistant bacteria are present in agricultural soils, and the isolated strain could be a good candidate for heavy metal removal from polluted environment.
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