Quorum sensing and quorum quenching activity induced by urea in Serratia marcescens

TUTTOBENE, MARISEL ROMINA; MOLINO, MARÍA VICTORIA; RAMÍREZ, MARÍA SOLEDAD; VESCOVI, ELEONORA GARCÍA

Congreso; SAIB-SAMIGE 2021; 2021

Serratia marcescens belongs to the family of Enterobacteriaceae and could be isolated from a wide variety of environmental niches, from water and soil to air. In addition to its environmental ubiquity, S. marcescens is an emerging health-threatening nosocomial pathogen. In recent years, numerous outbreaks of strains carrying multidrug resistance and a high incidence have been reported. In 2017, the World Health Organization declared S. marcescens, along with other Enterobacteriaceae, a priority research target to develop alternative antimicrobial strategies given the high frequency of clinical isolates resistant to carbapenems. Our laboratory study model is S. marcescens strain RM66262. This is a non-pigmented clinical isolate from a patient with urinary tract infection (UTI) from a hospital of Rosario, Argentina. Quorum sensing allows the bacteria to communicate cell-cell to monitor their population density, synchronize their behavior, and interact socially, while quorum quenching are different mechanisms that attenuate the quorum sensing. The major component of urine is urea, which has been shown to suppress the detection of quorum sensing in Pseudomonas aeruginosa, while the ability to produce acyl-homoserine lactones (AHL), the molecules of quorum sensing remained intact. In our laboratory, we carried out a transcriptional analysis of S. marcescens exposed to urea. The RNA-seq analysis showed that urea is a regulatory signal that increased the expression of a putative α/β hydrolase which has homology with the lactonase AidA described in Acinetobacter baumannii. Phenotypic assays confirmed that this quorum quenching activity is cytoplasmic, as most described lactonases, and has the ability to degrade AHL from Serratia and other bacteria such as P. aeruginosa. Furthermore, our results indicate that S. marcescens produced 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 expression of quorum sensing molecules as well as the quorum quenching activity.