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Table 2 Characteristics of Pseudomonas fluorescens OS8-based plasmid-containing 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 strain
  OS8(pDNmerRBSB
Pmerlux)
OS8(pDNpbrR
PpbrAlux)
OS8(pDNcadR
PcadAlux)
OS8(pDNlux)
Background luminescence a 1600 ± 540 3960 ± 1300 25900 ± 8700 64500 ± 6600
Maximum induction b 200 7 6 no induction
No of cells in the test (100 μl) 5 × 106 4 × 106 4 × 106 5 × 106
Compound Limit of determinationc/Toxicityd, M (mg of compound l-1) Toxicity (2-h EC50e), M (mg of compound l-1)
HgCl 2 10-9 (0.0003)/10-7 (0.04) 10-7 (0.04)/10-6 (0.4) 10-7 (0.03)/10-6 (0.4) 2.5 × 10-7 (0.07)
CH 3 HgCl 10-10 (0.00003)/10-7 (0.04) not tested not tested 2 × 10-6 (0.5)
CdCl 2 5 × 10-6 (0.9)/10-2 (2740) 8 × 10-7 (0.2)/5 × 10-4 (92) 6 × 10-8 (0.01)/10-4 (18) 4 × 10-2 (7300)
ZnSO 4 f No induction 4 × 10-5 (6.4)/5 × 10-2 (8050) 8 × 10-6 (1.3)/3 × 10-2 (4800) 3 × 10-2 (4800)
Pb(NO 3 ) 2 No induction 9 × 10-7 (0.3)/10-3 (500) 4 × 10-7 (0.1)/10-3 (500) 7 × 10-4 (230)
CuSO 4 g not tested not tested not tested not tested
AgNO 3 not tested not tested not tested not tested
  1. a 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
  2. b as fold over the (non-induced) background
  3. c see equation 4 in Methods
  4. d the lowest tested concentration causing a measurable decrease in the bioluminescence of the sensor strains (read from concentration-induction curves in Figure 1)
  5. e concentration causing 50% decrease in the bioluminescence production (calculated from Figure 2)
  6. f tested as ZnSO4 × 7H2O
  7. g tested as CuSO4 × 5H2O