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Table 3 Characteristics of Pseudomonas fluorescens OS8-based chromosomal 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::KnmerRBSBPmerlux OS8::KncueRPcopAlux OS8::KnzntRPzntAlux OS8::KnpbrR
PpbrAlux
OS8::KncadR
PcadAlux
OS8::Knlux
Background luminescence a 1290 ± 240 1250 ± 180 3530 ± 1570 84 ± 35 2860 ± 320 600–1400b
Maximum induction c 400 7 20 50 80 no induction
No of cells in the test (100 μl) 2 × 107 3 × 107 6 × 106 3 × 106 3 × 107 3 × 106 – 3 × 107b
Compound Limit of determinationd/Toxicitye, M (mg of compound l-1) Toxicity (2-h EC50f), M (mg compound l-1)
HgCl 2 3 × 10-9 (0.0008)/5 × 10-6 (1.3) no induction 3 × 10-7 (0.08)/5 × 10-6 (1.4) 3 × 10-8 (0.008)/10-6 (0.4) 2 × 10-8 (0.005)/10-6 (0.4) 5 × 10-7 (0.14)
CH 3 HgCl 3 × 10-9 (0.0008)/5 × 10-6 (1.3) not tested not tested not tested not tested 2 × 10-6 (0.58)
CdCl 2 5 × 10-5 (9.2)/5 × 10-2 (9150) no induction 8 × 10-8 (0.02)/10-2 (2750) 8 × 10-8 (0.02)/5 × 10-4 (92) 3 × 10-8 (0.006)/5 × 10-3 (915) 2 × 10-2 (3660)
ZnSO 4 g no induction no induction 3 × 10-5 (4.8)/5 × 10-2 (8050) 2 × 10-5 (3.2)/10-2 (2420) 4 × 10-6 (0.6)/2 × 10-2 (3220) 3.5 × 10-2 (5640)
Pb(NO 3 ) 2 no induction no induction 4 × 10-7 (0.1)/10-3 (500) 2 × 10-7 (0.07)/10-3 (500) 3 × 10-7 (0.1)/10-3 (500) 7 × 10-4 (231)
CuSO 4 h not tested 5 × 10-5 (8)/10-3 (240) not tested not tested not tested 8 × 10-3 (1280)
AgNO 3 not tested no induction not tested not tested not tested 5 × 10-7 (0.083)
  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 cells at different optical densities (see Methods) yielded different RLU values and number of viable cells
  3. c as fold over the (non-induced) background
  4. d see equation 4 in Methods
  5. e the lowest tested concentration causing a measurable decrease in the bioluminescence of the sensor strains (read from concentration-induction curves in Figure 1)
  6. f concentration causing 50% decrease in the bioluminescence production (calculated from Figure 2)
  7. g tested as ZnSO4 × 7H2O
  8. h tested as CuSO4 × 5H2O