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Table 1 Characteristics of Escherichia coli MC1061-based luminescent heavy metal sensors and toxicity control strains

From: A suite of recombinant luminescent bacterial strains for the quantification of bioavailable heavy metals and toxicity testing

  Sensor strains Control strains
  MC1061
(pmerRBSBPmerlux)
MC1061
(pSLzntR/
pDNPzntAlux)
MC1061 (pSLcueR/
pDNPcopAlux)
MC1061
(pSLlux)a
MC1061
(pDNlux)b
Background luminescence c 230 ± 90 2940 ± 930 520 ± 70 575000 ± 35200 6500 ± 2270
Maximum induction d 400 20 100 no induction no induction
No of cells in the test (100 μl) 4 × 107 107 8 × 106 8 × 106 107
Compound Limit of determinatione/Toxicityf, M (mg of compound l-1) Toxicity (2-h EC50g), M (mg of compound l-1)  
HgCl 2 10-10 (0.00003)/5 × 10-6 (1.4) 8 × 10-8 (0.02)/10-5 (2.7) no induction 10-6 (0.4) 10-6 (0.4)
CH 3 HgCl 8 × 10-12 (0.000002)/5 × 10-8 (0.01) not tested not tested 3 × 10-6 (0.7) not tested
CdCl 2 3 × 10-7 (0.06)/5 × 10-4 (92) 10-8 (0.003)/5 × 10-6 (0.9) no induction 4 × 10-4 (70) 2 × 10-4 (31)
ZnSO 4 h no induction 5 × 10-6 (0.8)/5 × 10-2 (8000) no induction 10-2 (1600) 4 × 10-3 (640)
Pb(NO 3 ) 2 no induction 7 × 10-7 (0.2)/10-3 (330) no induction 2.4 × 10-4 (79) 6 × 10-4 (190)
CuSO 4 i not tested not tested 10-7 (0.02)/10-3 (240) not tested 5.4 × 10-4 (86)
AgNO 3 not tested not tested 2 × 10-6 (0.3)/10-5 (2.6) not tested 2 × 10-6 (0.3)
  1. a control for MC1061(pmerRBSBPmerlux)
  2. b control for MC1061(pSLcueR/pDNPcopAlux) and MC1061(pSLzntR/pDNPzntAlux)
  3. c luminescence (relative light units, RLU) of 100 μl of bacterial suspension before the test as measured by plate luminometer Fluoroskan (ThermoLabsystems). Average of at least three assays
  4. d as fold over the (non-induced) background
  5. e see equation 4 in Methods
  6. f the lowest tested concentration causing a measurable decrease in the bioluminescence of the sensor strains (read from concentration-induction curves in Figure 1)
  7. g concentration causing 50% decrease in bioluminescence production (calculated from Figure 2)
  8. h tested as ZnSO4 × 7H2O
  9. i tested as CuSO4 × 5H2O