Release of extracellular ATP by bacteria during growth

Background: Adenosine triphosphate (ATP) is used as an intracellular energy source by all living organisms. It plays a central role in the respiration and metabolism, and is the most important energy supplier in many enzymatic reactions. Its critical role as the energy storage molecule makes it extremely valuable to all cells. Results: We report here the detection of extracellular ATP in the cultures of a variety of bacterial species. The levels of the extracellular ATP in bacterial cultures peaked around the end of the log phase and decreased in the stationary phase of growth. Extracellular ATP levels were dependent on the cellular respiration as bacterial mutants lacking cytochrome bo oxidase displayed lower extracellular ATP levels. We have also shown that Escherichia coli (E. coli) and Salmonella actively depleted extracellular ATP and an ATP supplement in culture media enhanced the stationary survival of E. coli and Salmonella. In addition to E. coli and Salmonella the presence of the extracellular ATP was observed in a variety of bacterial species that contain human pathogens such as Acinetobacter, Pseudomonas, Klebsiella and Staphylococcus. Conclusion: Our results indicate that extracellular ATP is produced by many bacterial species during growth and extracellular ATP may serve a role in the bacterial physiology.