Bioluminescence is a chemical reaction based on the oxidation of a substrate called luciferin (a light emitting pigment) by the luciferase enzyme, which results in energy emission in the form of light. This process requires six ATP molecules for each photon emitted.
This phenomenon is widely observable in nature: it is used by numerous organisms (bacteria, fungi, marine organisms) for different purposes such as reproduction and predation. It must not be mistaken with fluorescence, which comes from the restitution of an absorbed photon by an excited molecule [1][2][3]

Environmental monitoring

Application

Applications include construction of biosensors for detection of pollutants and pathogens. It can be used to monitor genetically engineered bacteria released into the environment. Biosensors are particularly useful in bioremediation studies in which they can be used to determine the presence, bioavailability, and concentrations of specific pollutants.

Bioluminescence as an indicator of cellular metabolic activity can be used to monitor the biological activity and toxicity of pollutants.[1]

Rferences (Links are provided when available):

1. Nunes-Halldorson, V. da S., and Duran, N.L. (2003). Bioluminescent bacteria: lux genes as environmental biosensors. Brazilian Journal of Microbiology 34.

2. Wu, N., Rathnayaka, T., and Kuroda, Y. (2015). Bacterial expression and re-engineering of Gaussia princeps luciferase and its use as a reporter protein. Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics 1854, 1392–1399.

3. Wiles, S., Ferguson, K., Stefanidou, M., Young, D.B., and Robertson, B.D. (2005). Alternative Luciferase for Monitoring Bacterial Cells under Adverse Conditions. Applied and Environmental Microbiology 71, 3427–3432.