Copper and lead removal from aqueous solutions by bacterial consortia acting as biosorbents

A bacterial consortium was selected in the presence of Cu from sediment samples taken from Sepetiba Bay, Brazil, which is a site historically contaminated by metals. Bacteria were exposed to 0, 1, 6, 12.5, 25 and 50 1 mu g.mL(-1) Cu, Pb and Cu + Pb for 11 days of bioassay. Results showed Alcanivorax dominance (81%) and cell counts of 10(8) cells.mL(-1) However, a reduction in dehydrogenase activity was observed from the fifth day of exposure for all Cu, Pb, and Cu + Pb concentrations tested. Esterase activity tended to increase, indicating higher energy demand to complete the bacterial lifecycle. Pb concentrations in the filtered culture medium (0.2 mu m) were below the detection limit, indicating biosorption, whereas concentrations of Cu were dose to the tested concentrations, indicative of efflux. Results suggest the need for biomarkers, such as esterase and dehydrogenase enzymatic activity, in the assessment of resistance and tolerance of communities previously exposed to stressors. (C) 2016 Elsevier Ltd. All rights reserved.