What is Atp bioluminescence?

What is ATP or Adenosine triphosphate?

formule chimique de l'ATP
Adenosine triphosphate

Adenosine triphosphate (ATP) is a vital molecule for the functioning of any living cell. It can be considered as a kind of chemical “battery” that stores and supplies energy to cells according to their needs.

The ATP or Adenosine triphosphate is composed:

  • a base called adenosine (composed of a ribose molecule linked to an adenine molecule) as described on the chemical formula opposite;
  • connected to a group of three phosphate molecules linked together by high energy bonds. When one of these bonds is broken or cleaved, a large amount of energy is released.

 No dead cell produces ATP, which is rapidly degraded in dead cells by the action of enzymes degrading ATP present in the cell or in the environment.

This characteristic of living cells that only produce ATP is exploited: to discriminate living cells from dead ones, by detecting their ATP.

With one exception: some microorganisms exposed to certain UV wavelengths that damage DNA without damaging the microbial membrane, retain their intra-cellular ATP. However in this case the ATP content remains constant without any increase, because there is no more ATP production.

Even in this case the microbial cell will degrade and release at some point its intracellular ATP or degrade it.


Once ATP has released its energy through bioluminescence, it becomes adenosine monophosphate (AMP) with a single phosphate group.

Adenosine monophosphate

ATP bioluminescence detects Adenosine triphosphate.

Atp bioluminescence reaction in presence of Luciferin-luciferase complex.

The ATP detected by Atp bioluminescence may be:

    1. either free ATP released from damaged or dead cells
    2. or adenosine triphosphate released by cells by lysis during ATP analysis.

How is Adenosine triphosphate or ATP analyzed?

firefly emitting light at night

When ATP is released by a cell and mixed with a complex (or mixture) comprising a substrate luciferin and an enzyme luciferase, a luminous reaction occurs, we speak of a bioluminescence reaction of ATP.

This reaction is the same as the biochemical process that  allow  firefly to produce light.

Luciferin serves as a substrate for the bioluminescence reaction triggered by the enzyme luciferase which cleaves (removes components of) the adenosine triphosphate molecule including two phosphate groups if the bioluminescence reaction is complete.

Once the ATP becomes AMP it cannot produce bioluminescence any more.

A two-step ATP bioluminescence reaction

two phases of Atp bioluminescence

The bioluminescence of ATP occurs in two stages.

During the first phase, luciferin interacts with ATP in the presence of magnesium ions (Mg++) and luciferase to produce luciferyl adenylate (a combination of luciferin and adenosine monophosphate), diphosphate or pyrophosphate (PPi), and CO2.

Luciferin + ATP ————-> Luciferyl adénylate + PPi + CO2



In the second phase, still in the presence of luciferase, luciferyl adenylate reacts with oxygen to form a transient peroxy group (R-O-O-R) that is highly unstable within luciferyl adenylate. When this group breaks, it excites the whole system and causes the emission of light. luciferyl adenylate + O2 ————-> oxyluciferin + AMP + light

Luciferyl adenylate + O2 ————-> oxyluciferin + AMP + light

ATP bioluminescence proportional to microorganisms concentration?

ATP bioluminescence is theoretically proportional to the viable fungal or bacterial population and should allow to quantify the concentration level of these flora in:


  •    drinking water, process water
  •     wastewaters
  •     ballast waters
  •     air
  •     surfaces
  •     fuels
  •     beverages.
  •     and for disinfection control.

However, classical Atp testing methods, in particular 1st and 2nd generation Atpbioluminescence kits face technical problems, some of which are insurmountable.

To understand why,, read our page on the unsolved Atp bioluminescence problems of 1st and 2nd generation Atpmetry kits.


How is ATP bioluminescence measured?

LCD display of bioluminometer measures light emission in RLU's (relative light units).

A bioluminometer measures the light reaction intensity. Values  displayed by the bioluminometer LCD are in RLU’s (relative light units). There are different types of bioluminometers, some are less sensitive than others due to the their detector sensitivity but also due to their consumables and reagents sensitivity to quenching substances.

This ATP bioluminescence reaction is theoretically proportional to viable yeasts or bacteria population and should make it possible to quantify the concentration level of these bacteria or yeasts in the analyzed beverages. However classic Atp test methods have to overcome difficult technical issues. To understand why go to our  Atp bioluminescence unsolved issues page. You will better understand what are the limitations of 1st generation 2nd generation  and 3rd generation Atp bioluminescence test kits.

Read our next page dealing with classic issues raised by current Atp methods by clicking on the button on the right.