EBPI SOS-ChromoPad^TM is a modified version of the SOS-ChromoTest^TM kit which uses a chromogenic pad to test for genotoxicity in sediments directly, without extraction. The SOS-ChromoPad^TM is a rapid bacterial-based colorimetric bioassay kit for the determination of toxicity of sediments, suspended sediments, soils and solid wastes. It is sensitive to a wide spectrum of toxic substances such as heavy metals, and organic and inorganic pollutants, and may be used to detect the presence of toxicants directly without solvent extraction. The assay is based on the ability of substances (toxicants) to inhibit the de novo synthesis of an inducible enzyme – β-galactosidase – in a highly permeable mutant of E. coli.

The sensitivity of the test is enhanced by exposing the bacteria to stressing conditions, after which they are rehydrated in a cocktail containing a specific inducer of β-galactosidase, and essential factors required for the recovery of the bacteria from their stressed condition. The activity of the induced enzyme is detected by the hydrolysis of a chromogenic substrate. Toxic materials interfere with the recovery process and thus with the synthesis of the enzyme and the colour reaction. Lab Tests on this bioassay show that the SOS-ChromoPad^TM is high sensitive, consistent and discriminative.