Identification of Unanticipated and Novel N-Acyl L-Homoserine Lactones (AHLs) Using a Sensitive Non-Targeted LC-MS/MS Method

• Published in: PloS one Vol. 11; no. 10; p. e0163469
• Main Authors: Patel, Nishaben M, Moore, Joseph D, Blackwell, Helen E, Amador-Noguez, Daniel
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 05.10.2016; Public Library of Science (PLoS)
• Subjects: Acyl-Butyrolactones - chemistry; Acyl-Butyrolactones - isolation & purification; Agrobacterium tumefaciens; Bacteria; Bacteriology; Biodegradation; Biology and Life Sciences; Biosensors; Chains; Chromatography; Chromatography, High Pressure Liquid - methods; Degradation; E coli; Escherichia coli; Genes; Gram-negative bacteria; Gram-Negative Bacteria - classification; Gram-Negative Bacteria - metabolism; High performance liquid chromatography; High resolution; Homoserine lactones; Identification; Lactones; Liquid chromatography; Mass spectra; Medicine and Health Sciences; Methods; Microorganisms; Molecular Structure; Physical Sciences; Proteins; Pseudomonas aeruginosa; Quadrupoles; Quorum Sensing; Research and Analysis Methods; Serratia; Signaling; Species Specificity; Tandem Mass Spectrometry - methods; Yersinia; United States > US; Wisconsin
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0163469

N-acyl L-homoserine lactones (AHLs) constitute a predominant class of quorum-sensing signaling molecules used by Gram-negative bacteria. Here, we report a sensitive and non-targeted HPLC-MS/MS method based on parallel reaction monitoring (PRM) to identify and quantitate known, unanticipated, and novel AHLs in microbial samples. Using a hybrid quadrupole-high resolution mass analyzer, this method integrates MS scans and all-ion fragmentation MS/MS scans to allow simultaneous detection of AHL parent-ion masses and generation of full mass spectra at high resolution and high mass accuracy in a single chromatographic run. We applied this method to screen for AHL production in a variety of Gram-negative bacteria (i.e. B. cepacia, E. tarda, E. carotovora, E. herbicola, P. stewartii, P. aeruginosa, P. aureofaciens, and R. sphaeroides) and discovered that nearly all of them produce a larger set of AHLs than previously reported. Furthermore, we identified production of an uncommon AHL (i.e. 3-oxo-C7-HL) in E. carotovora and P. stewartii, whose production has only been previously observed within the genera Serratia and Yersinia. Finally, we used our method to quantitate AHL degradation in B. cepacia, E. carotovora, E. herbicola, P. stewartii, P. aeruginosa, P. aureofaciens, the non-AHL producer E. coli, and the Gram-positive bacterium B. subtilis. We found that AHL degradation ability varies widely across these microbes, of which B. subtilis and E. carotovora are the best degraders, and observed that there is a general trend for AHLs containing long acyl chains (≥10 carbons) to be degraded at faster rates than AHLs with short acyl chains (≤6 carbons).