Selection and Characterization of an RNA‐Cleaving DNAzyme Activated by Legionella pneumophila

Legionella pneumophila is a deadly bacterial pathogen that has caused numerous Legionnaires’ disease outbreaks, where cooling towers were the most common source of exposure. Bacterial culturing is used for L. pneumophila detection, but this method takes approximately 10 days to complete. In this work, an RNA‐cleaving fluorogenic DNAzyme, named LP1, was isolated. Extensive characterization revealed that LP1 is reactive with multiple infectious isolates of L. pneumophila but inactive with 25 other common bacterial species. LP1 is likely activated by a protein target, capable of generating a detectable signal in the presence of as few as 10 colony‐forming units of L. pneumophila, and able to maintain its activity in cooling tower water from diverse sources. Given that similar DNAzymes have been incorporated into many sensitive assays for bacterial detection, LP1 holds the potential for the development of biosensors for monitoring the contamination of L. pneumophila in exposure sources. Legionella pneumophila is a pathogenic bacterium that exists in naturally occurring and man‐made water sources. Contaminations with these bacteria in cooling towers have led to fatal disease outbreaks. An RNA‐cleaving fluorogenic DNAzyme was isolated and found to selectively recognize Legionella pneumophila bacteria in cooling tower water. RNA‐cleaving DNAzymes are synthetic DNA enzymes that can be easily incorporated into biosensor designs.