ABSTRACT

Bioremediation as a bioprocess has great potential to reduce the toxicity of heavy metals such as lead (Pb) from contaminated sites. In this study, the Pb-bioremediation potential of Microbacterium oxydans CM3 and CM7 (individually and a mixture of both strains) was evaluated. To improve the Pb-bioremediation efficiency, the response surface methodology (RSM) was used to optimize the process factors responsible such as pH, temperature, and initial Pb concentration. The optimum condition for strain CM3 was observed at pH 6.81, temperature 35.31 °C, the Pb concentration of 337.35 mg/L, and the Pb removal was 60.42%. However, the strain CM7 showed the maximum Pb remediation at temperature 35.65, pH 5.28, the Pb concentration of 346.95 mg/L and the Pb removal was 59.05%. Among the studied bacteria, mixture culture (containing both strains) was more able to remove Pb than a single culture. Our result found that the Pb was precipitated as insoluble form at pH≥6.5 by M. oxydans strain CM3 and insoluble Pb-phosphate compound in the cell wall was confirmed using SEM and EDS. This study revealed that M. oxydans strain CM3 and CM7 have a high Pb remediation potential and could be used to remove Pb(II) from contaminated environments.

摘要

生物修复作为一种生物过程具有巨大的潜力，可以减少污染场地中重金属（例如铅（Pb））的毒性。在这项研究中，氧化微细菌的Pb生物修复潜力评估了CM3和CM7（分别和两种菌株的混合物）。为了提高Pb的生物修复效率，使用了响应面方法（RSM）来优化负责的工艺因素，例如pH，温度和初始Pb浓度。在pH 6.81，温度35.31°C，Pb浓度337.35 mg / L，Pb去除率为60.42％的条件下观察到了CM3菌株的最佳条件。但是，菌株CM7在温度35.65，pH 5.28，Pb浓度为346.95 mg / L和Pb去除率为59.05％时显示出最大的Pb修复。在所研究的细菌中，混合培养（包含两种菌株）比单一培养物更能去除Pb。我们的结果发现，Pb在pH≥6.5时被氧化单胞菌沉淀为不溶形式。使用SEM和EDS确认了CM3菌株和细胞壁中的不溶性Pb-磷酸盐化合物。这项研究表明，氧化单胞菌菌株CM3和CM7具有较高的Pb修复潜力，可用于从受污染的环境中去除Pb（II）。