Removal of cadmium and lead from aqueous solution by Enterococcus faecium strains.

Foods may be contaminated with heavy metals, which, even in small quantities, possess detrimental effects on human health. The aim of the present study was to investigate the uptake of cadmium or lead from an aqueous medium frequently found in foods, by 2 Enterococcus faecium strains (E. faecium EF031 and E. faecium M74). Also, the effects of the bacterial viability, incubation (contact) time, and pH on the binding capacities and binding stability were assessed. The results showed that both of the strains efficiently removed cadmium and lead. While EF031 removed 77.3% to 98.1% of cadmium and 66.9% to 98.9% of lead, M74 removed 53.5% to 91% of cadmium and 42.9% to 93.1% of lead throughout a 48 h incubation period at pH 5. It was found that, at 1 h, EF031 and M74 strains removed cadmium and lead, which was more than 60% of total removed cadmium and lead throughout the whole incubation period of 48 h. It suggests that the uptake of cadmium and lead by EF031 and M74 strains is a rapid process. The binding of both heavy metals increased with increasing pH of an aqueous medium and was the highest at pH 5. Also, the complexes formed between both heavy metals and bacterial cells were found to be stable. These findings indicate that E. faecium strains used in the study are able to bind the 2 heavy metals and may be used in the production of fermented functional foods, which will be healthy via its detoxification properties.