Genetically engineered E. coli JM109 was used in this
study, which simultaneously harboured two compatible
plasmids, pSUTP, containing the merP and merT genes,
and pGPMT containing the GST-PMT fusion gene [7].
Frozen cells were inoculated into Luria broth (LB) containing
50 mg/L ampicillin and 30 mg/L kanamycin, grown
overnight at 37 8C, and then re-inoculated into fresh LBs
containing ampicillin and kanamycin as well as different
concentrations of Hg2+ to an initial OD600 of 0.1. During the
incubation at 37 8C and vigorous shaking (180 r/min), samples
were collected from shaking flasks at various times to
measure OD600 and the Hg2+ concentration of the supernatant
after cell centrifugation.