AUTHOR=Vivero-Gomez Rafael Jose , Mesa Gustavo Bedoya , Higuita-Castro Jorge , Robledo Sara M. , Moreno-Herrera Claudia X. , Cadavid-Restrepo Gloria TITLE=Detection of Quorum Sensing Signal Molecules, Particularly N-Acyl Homoserine Lactones, 2-Alky-4-Quinolones, and Diketopiperazines, in Gram-Negative Bacteria Isolated From Insect Vector of Leishmaniasis JOURNAL=Frontiers in Tropical Diseases VOLUME=Volume 2 - 2021 YEAR=2021 URL=https://www.frontiersin.org/journals/tropical-diseases/articles/10.3389/fitd.2021.760228 DOI=10.3389/fitd.2021.760228 ISSN=2673-7515 ABSTRACT=Gram-negative bacteria use a Quorum Sensing system based on N-Acyl Homoserine Lactones and 2-Alkyl-4-quinolones signaling molecules. Both facilitate and stimulate cell to cell communication through the regulation of specific genes, to modulate cell density, metabolic and physiological processes that can affect either survival of insect vectors or the establishment of pathogens. This study aims at portraying the detection and identification of Quorum Sensing signal molecules type AHLs and AHQs, secreted by intestinal bacteria, linking their production to their extracellular milieu and intracellular content. Isolates were obtained from the intestinal tract of Pintomyia evansi. AHLs and AHQs molecules was detected on Thin Layer Chromatography assays using specific and sensitive biosensors, while identity confirmation was developed by Ultra-High-Performance Liquid Chromatography coupled with mass spectrometry. Using TLC, pronounced detection of QSM was obtained in the supernatant of isolates in relation to intracellular content. Pseudomonas otitidis, Enterobacter cloacae, and Pantoea ananatis isolates showed a migration pattern similar to the OHHL (3-Oxo-C6-HSL) synthetic molecule used as a control. Enterobacter cancerogenus secreted HHL (N-hexanoyl homoserine lactone (C6-HSL)) related molecules, while Acinetobacter gyllenbergii exhibited a migration pattern like HHQ (2-heptyl-4-quinolone) molecules. OdDHL (3-Oxo-C12-HSL) type molecules were produced by Pseudomonas putida, Pseudomonas aeruginosa, and Enterobacter cloacae bacteria like PQS (2-heptyl-3 hydroxy-4-quinolone). Peaks chromatograms with retention times and areas consistent with the molecules described in the TLC, for Pseudomonas putida, Enterobacter aerogenes, Pantoea ananatis, and Pseudomonas otitidis extracts were obtained using HPLC; nonetheless, Pantoea ananatis produced a greater variety of high QSM concentration, thus serving as a reference for confirmation and identification by UHPLC-MRM-MS/MS. Among the identified molecules are HHL (C10H18NO3, [M+H]), OHHL (C10H16NO4, [M+H]), OdDHL (C16H28NO4, [M+H]) and PQS (C16H22NO2, [M+H]). Besides, the detection of diketopiperazines Cyclo (L-Pro-L-Tyr) and Cyclo (Ξ”Ala-L-Val) cyclopeptides were reported. These molecules may potentially be associated with the regulation of the QSM system. This is the first report about detection and identification of QSM and diketopiperazines in gut sand fly bacteria. The possible influence of QSM in the establishment of Leishmania must be explored to determine the role in the modulation of the intestinal microbiome and the life cycle of Pi. evansi as well.