Bioluminescence is best known from the glow of a firefly tail. It occurs when luciferase and luciferin come into contact with the molecule ATP (adenosine triphosphate), which is present in all living organisms. Rapid microbial screening systems use ATP bioluminescence and sensitive light instruments called luminometers to reveal the presence of microbes (that contain ATP) in product samples. The result is an emission of light that is directly proportionate to the amount of ATP present in the sample. ATP bioluminescence technology has been around for 40 years, but only since the introduction of selective extraction reagents has the potential for this technology been available for use in a broad range of manufacturing industries. RMM results using ATP typically are available within 24–48 hours vs. three to seven days using agar plates.
The latest development in the field of bioluminescence is the use of the enzyme adenylate kinase (AK), another vital part of energy metabolism that is present in all living organisms. Because AK is an enzyme, rather than a metabolite, it is possible to use AK to generate almost unlimited amounts of ATP, which can then be detected by a conventional bioluminescence assay. This technology makes it possible to get test results in 18–24 hours, which is 25% to 50% faster than current ATP-based screening methods that can take up to 48 hours.
The following diagram compares traditional micro-testing methods to newer rapid detection methods in the manufacturing production process. By compressing the time required for micro-testing at various stages of production, manufacturers can significantly streamline cycle times. The cumulative effect of these cycle time savings is substantial—up to 12 days in this case.