Adaptation of the bacterial community to mercury contamination

The utilisation of 31 sole carbon sources by bacterial communities of soil in the presence of increasing concentrations of Hg(II) was measured by a co lour development assay. The assay was performed on Biolog microtitre plates (Ecoplates) in the presence of Hg(II) and compared to Hg(II)-free Ecoplate s. Furthermore, community tolerance to Hg(II) was measured by colour develo pment in microtitre plates supplemented with LB broth and by enumeration of colony-forming units on LB agar plates. Both microtitre plates supplemente d with LB and LB agar plates contained increasing concentrations of Hg(II). The difference in substrate utilisation profile, as shown by growth on 31 different carbon substrates in the Ecoplates, suggested an adaptation of th e soil community that correlated with the metal exposure level in the soil. Similarly, growth on microtitre plates supplemented with LB and plate-spre ading data showed an increased community tolerance with increasing levels o f mercury in the soil. Both the multi-function microtitre plate assay (Ecop late) and the LB broth microtitre plate assay are suitable for evaluating t he adaptation of the bacterial community in soil to a heavy metal pollutant . (C) 2001 Published by Elsevier Science B.V. on behalf of the Federation o f European Microbiological Societies.