The marine bacterium Vibrio fischeri is widely used for the toxicity assessment of environmental samples. The toxicity is measured in a medium containing 2% NaCl. When the bacteria are exposed to toxic compounds, the light production is inhibited. Toxicity values are obtained after 15 and 30 minutes exposure and expressed as EC50 values, the effective concentration causing 50% loss in light emission. Because of the general presence of metals in our environment, study of their toxicity is important. In chloride containing media, many metals form chlorocomplexes resulting in an increase of the EC50 values.
In order to improve the sensitivity of the test, especially for online monitoring using the iTOXcontrol (Figure 1), alternative salt mixtures were tested: sucrose, NaClO4 and the ProMet buffer of microLAN.
Improved sensitivity to heavy metals in the bioluminescence assay using alternative salt solutions