Patulin interference with ATP binding cassette transferring auto inducer −2 in Salmonella typhi and biofilm inhibition via quorum sensing

Salmonella typhi are Gram-negative pathogens that infect many hosts including humans and animals, and cause diseases ranging from gastroenteritis and diarrhea to life-threatening systemic syndrome. Owing to the metabolic versatility, they will colonize as multicellular aggregates on various surfaces to enhance the virulence by forming a biofilm in which bacterial cells are more resistant to antibiotics than planktonic cells. Quorum Sensing (QS) is a cell-to-cell communication mechanism in the bacterial system which acts to coordinate group behaviors such as biofilms formation and virulence factors production. In the QS system ATP Binding Cassette (ABC) transporter component, LsrA plays a key role to transport autoinducer-2 (AI-2) for increasing cell density. In order to reduce biofilm formation, patulin was selected as a natural QS inhibitor and its function was studied by a biofilm inhibitory assay. Significant differences in the spectroscopic values were obtained between antibiotic resistance of kanamycin (30μg/ml) and patulin (30μg/ml). Furthermore, to distinguish the molecular-level interaction of patulin and AI-2, they were docked with LsrA. Both the compounds were docked in the same pose with Glide scores of −4.237 Kcal/mol and −7.126 Kcal/mol respectively. These preliminary results suggested that patulin is an efficient Quorum Sensing Inhibitor for controlling biofilm formation in S.typhi. Keywords: Salmonella typhi, Quorum sensing, LsrA, AI-2, Patulin