A bacterial bioluminescence test (BBT) is a metabolic inhibition test that uses luminescent bacteria to measure a substance’s toxicity. This method provides a rapid, reliable, and convenient means of determining acute toxicity. The BBT has been validated for various environmental applications (e.g., effluent monitoring; groundwater, drinking water, sediment,1,2 and hazardous waste testing; bioremediation-efficiency assessments; and general biomonitoring).
Luminescent bacteria possess several attributes useful for toxicity testing. Certain strains of luminescent bacteria divert up to 10% of their respiratory energy into the luciferase metabolic pathway that converts chemical energy into visible light by the enzymatic catalysis of a chemical substrate. This pathway is intrinsically tied to respiration; any change in cellular respiration or disruption of cell structures changes respiration and, therefore, the amount of bioluminescence.
In bacteria, many metabolic pathways are in or near the cell membrane, including those pathways related to respiration, oxidative phosphorylation, osmotic stabilization, and transport of chemicals and protons into and out of the cell. The luciferase enzymes, which shunt electrons directly to oxygen at the level of reduced flavin mononucleotide, are also in the cell membrane.3 Because luminescent bacteria are small (< 1 μm diam), have relatively simple morphology, and have no membrane-sided compartmentalization of internal functions, they provide many target sites at or near the cell membrane for toxicants to exploit.