Use of biosensors to screen urine samples for potentially toxic chemicals

Forensic toxicology laboratories are often required to implicate or exclude poisoning as a factor in a death or unexplained illness. An analytical tool which enables toxicologists to screen a wide variety of common poisons would be extremely useful. In this paper, we describe the use of a bacterial biosensor for detecting the presence of commonly encountered potentially toxic chemicals in urine. The biosensor responds to any chemical that causes metabolic stress to the bacterial cell and the response is in direct proportion to the concentration of the stressor. This allows a measure of the concentration of a toxicant in urine, without knowing exactly what the toxic compound(s) may be. This affords a distinct advantage over conventional analytical techniques, which require an extensive screening program before it is even known that a toxic compound is present. This preliminary investigation has shown that this biosensor can indicate the presence, in urine, of herbicides such as glyphosate, 2,4-dichlorophenoxyacetic acid, and 2,4,5-trichlorophenoxyacetic acid; the biocide pentachlorophenol; or inorganic poisons such as arsenic, mercury, and cyanide. The biosensor was also shown to be sensitive to a concentration range of these toxicants likely to be found in samples submitted for toxicological analysis.