Detection of Listeria species with the DETECT/L assay begins with the production of an enzyme from Listeria cells interacting with our engineered phage. RLU (Relative Light Units) is produced when this enzyme combines with our substrate (Detection reagents). RLU above a calculated threshold will read as a "presumed positive" result on the CONTROL app for iPad.
This "presumed positive" result triggers the DETECT Check step on the app. This step verifies that the "presumed positive" result is due to the detection of Listeria species and not a result of other environmental factors. After performing the DETECT check step, the tube is read again by the DETECT Reader:
- If the Reader detects a decrease in light (RLU) below a calculated percentage of its original value (before addition of DETECT check solution), a "presumed positive" result will be recorded for that sample. The DETECT check solution has deactivated some of the available enzyme resulting in decreased light signal.
- If the RLU value remains relatively the same or higher (above a calculated percentage of the original value before DETECT check solution) the sample will be recorded as a "negative" result. It is likely that the initial high RLU value was due to other environmental factors.