Lead-resistant bacteria from Saint Clair River sediments and Pb removal in aqueous solutions

Lead is an extensive contaminant. Pb-resistant bacterial strains were isolated from Saint Clair River sediments on two enrichment media with increasing concentrations of Pb (NO₃)₂. Bacterial strains that grew at 1.25 or 1.5 g L^-1 of Pb (NO₃)₂ L^-1) were purified and selected for further study. Ninety-seven Pb-resistant strains were screened for the ability to produce bioflocculants. The majority of the Pb-resistant strains demonstrated moderate to high flocculation activity. Metal removal assays demonstrated that the higher is the flocculation activity, the higher is the efficiency of metal removal. In the multi-metal solutions, the bacterial strain with the highest flocculation activity (R19) had the highest metal removing capability (six out of eight metals) and the highest metal removal efficiency. The highly selective affinity towards Pb²⁺ observed for strain R19 suggests its use for the recovery of Pb²⁺ from multiple metal solutions. Because they are well adapted to unfavorable conditions due to their resistance to metals (e.g., Pb) and antibiotics, these characteristics may help in developing an effective process for wastewater treatment using these strains.