ATP bioluminescene:

Principles:

Make use of adenosine triphosphate, an energy donar for metabolic reactions in cell to measure cell varbility.
ATP level in a cells remain relatively constant and the content decrease sharply when cell death, thus allow the measure of biomass and cell viability.
Luciferase-luciferin (enzyme-substrate complex) catalyzes the conversion of ATP into light.
Amount of light emitted is directly proportional to the concentration of ATP which in term measure the number of variable cell.
Quantified using light detection devices.
Adenylate kinase (AK)
- An intracellular enzyme
- Equilibrates AMP, ADP and ATP by the reaction:
MgATP + AMP <=> MgADP + ADP
- When excess ADP is used as substrate, ATP will be produced in an amount proportional to the concentration of AK present which is then assayed using the luciferin-luciferase system.
- From the turnover number and the cellular ratio of AK to ATPit was predicted that, with 1 minute incubation, 40-50 times more ATP would be present for bioluminescent detection.

Assays to detect particular pathogens:
- Antibody-based bioluminescent assays
- Phage-based bioluminescent assays

Reference: M.Griffiths and L.Brovo. 2003. ATP bioluminescene. In: Thomas A. McMeekin. Detecting pathogens in food. North America: CRC Press LLC.166 and 174-178.