Extracellular metal-binding activity of the sulphate-reducing bacterium Desulfococcus multivorans

Polarography was used to measure the copper-binding ability of culture filtrates from a range of sulphate-reducing bacteria (SRB), including pure cultures and environmental isolates. Of those tested, Desulfococcus multivorans was shown to have the greatest copper-binding capacity and this organism was used for further experiments. Extracellular copper- and zincbinding activities of Dc. multivorans culture filtrates from batch cultures increased over time and reached a maximum after 10 d growth. The culture filtrate was shown to bind copper reversibly and zinc irreversibly. Twelve-dayold Dc. multivorans culture filtrates were shown to have a copper-binding capacity of 3<64O 0<33 lmol ml N1 with a stability constant, log10K ,o f 5<68O 0<64