The growing colonies were recorded and repeatedly inoculated on to LB plates with the same and higher Cd concentrations. Bacteria which could tolerate the highest Cd concentration, and had visually distinguishable colony types, were selected, purified, and stored on LB slants at−70 °C for subsequent experiments. Three isolates (2#, 9# (predominant Cd accumulator) and 12#)of the most Cd-tolerant bacteria grown on the LB plates were selected for further study.