QUORUM SENSING AND QUORUM QUENCHING ACTIVITY INDUCED BY UREA IN Serratia marcescens

TUTTOBENE, MARISEL R.; MOLINO, MV; RAMIREZ, MARIA SOLEDAD; ELEONORA, GARCIA VÉSCOVI

Evento ONLINE (por pandemia)

Congreso; LVII Annual Meeting of SAIB and XVI Annual Meeting of SAMIGE; 2021

SAIB-SAMIGE

Serratia marcescens belongs to the family of Enterobacteriaceae and could be isolated from a wide variety of environmentalniches, from water and soil to air. In addition to its environmental ubiquity, S. marcescens is an emerging health-threateningnosocomial pathogen. In recent years, numerous outbreaks of strains carrying multidrug resistance and a high incidence havebeen reported. In 2017, the World Health Organization declared S. marcescens, along with other Enterobacteriaceae, a priorityresearch target to develop alternative antimicrobial strategies given the high frequency of clinical isolates resistant tocarbapenems. Our laboratory study model is S. marcescens strain RM66262. This is a non-pigmented clinical isolate from apatient with urinary tract infection (UTI) from a hospital of Rosario, Argentina. Quorum sensing allows the bacteria tocommunicate cell-cell to monitor their population density, synchronize their behavior, and interact socially, while quorumquenching are different mechanisms that attenuate the quorum sensing. The major component of urine is urea, which has beenshown to suppress the detection of quorum sensing in Pseudomonas aeruginosa, while the ability to produce acyl-homoserinelactones (AHL), the molecules of quorum sensing remained intact. In our laboratory, we carried out a transcriptional analysisof S. marcescens exposed to urea. The RNA-seq analysis showed that urea is a regulatory signal that increased the expressionof a putative α/β hydrolase which has homology with the lactonase AidA described in Acinetobacter baumannii. Phenotypicassays confirmed that this quorum quenching activity is cytoplasmic, as most described lactonases, and has the ability todegrade AHL from Serratia and other bacteria such as P. aeruginosa. Furthermore, our results indicate that S. marcescensproduced AHL under static growth conditions (quorum sensing), while lactonase activity occurred under shaking conditions(quorum quenching) when was exposed to urea treatment. We can conclude that urea is a signal that modulates the expressionof quorum sensing molecules as well as the quorum quenching activity.