The study of two plant extracts inhibitory to the quorum sensing of Chromobacterium violaceum CV026

Many bacteria utilize quorum sensing mechanism in order to coordinate their vital functions such as survival, motility, production of biofilm, pathogenicity factors, etc. Interfering with the complicated cell-to-cell communication system paralyses bacterial calls to perform their different indigenous functions like pathogenicity. In this study interfering effects of two distinguished plant extracts, whitetop and dill, on bacterial quorum sensing of Chromobacterium violaceum CV026 was evaluated. Whitetop and dill plant species were collected from the surrounding agricultural areas and commercial fields of Urmia City. The collected plants were extracted using three organic solvents, 96% ethanol, n-hexane and methanol. The Antimicrobial susceptibility and anti-quorum sensing bioassays were then performed to find out their bactericidal property and depletion of violacein, respectively. Furthermore, the assays regarding pathogenicity suppression using anti-quorum sensing activity and acyl homoserine lactone induction through Pectobacterium carotovorum subsp. carotovorum strain were carried out. Based on the results, both of the plant extracts possess meaningful anti-QS activities; however, the proportion of the activity in whitetop was fewer than dill. Furthermore, the aforementioned plant extracts had bactericidal activity in which whitetop had more proportion in comparison to dill. Due to decrease in the production level of violacein by CV026 as a result of the anti-quorum sensing activity of whitetop and dill extracts, application of the extracts can be considered as an appropriate approach for controlling bacterial pathogens without developing resistance.