The concept exploited by the laboratory is the ability of specific enzymes from the pathogenic bateria to cut an exogenous volatile compound out of an introduced designed substrate. In the case of E-Coli bacteria for example, the beta-D-glucuronidase enzyme in the bacteria culture can release nitrophenol from the 4-nitrophenyl-beta-D-glucuronide substrate.
The released gaseous nitrophenol is then trapped in a nanoporous matrix, which acts as a sponge and concentrates this analyte, which is then detected via its absorbance at 400 nm. The detection time can be reduced to 24 hours with a bacteria culture inoculated with 100 cfu (colony-forming units).
The concept can also be applied to Salmonella, another frequently encountered pathogen in food. Here the target reaction will be the release of a highly volatile compound via the reaction of C8-esterase enzyme with a substrate bearing an ester group. Finally, the potentiality of the basic method is high, since both the sensitivity and time of detection of the method can still be improved with the use of fluorescent exogenous volatile compounds.