Investigation of the effects of various plant extracts on quorum sensing and virulance properties of Salmonella spp.

Inhibiting the Quorum Sensing System (QS) in bacteria is one of the current approaches to combat the development of antimicrobial resistance. In this study, the effectiveness of tetra and cranberry extracts, which were found to have lower antimicrobial activity from plants used in gastrointestinal disorders in the Thrace region (tetra, cranberry, chamomile, mallow, plantain), were evaluated on QS and QS-related biofilm and motility properties in different Salmonella serotypes isolated from foods (S. Hadar, S. Typhimurium, S. Anatum, S. İnfantis, standart S. Typhimurium ATCC 14028). A fast and economical colorimetric method that can detect AI-2 molecules was used for the first time in evaluating the effectiveness of plant extracts on the QS system. It was determined that cranberry (5mg/ml) and tetra (1mg/ml) extracts at subMIC (≤1/16 MIC) concentrations were effective at varying rates across serotypes; in QS inhibition (16%-35%), in biofilm formation inhibition in the food matrix (in microplate: tetra-chicken broth 88%,cranberry-lettuce broth 78%; in steel coupon: tetra-lettuce broth 99%, cranberry- chicken broth 86%), in inhibiton of contamination from steel coupon to food (tetra-chicken meat and lettuce contamination 95%; cranberry-meat 86%, cranberry-lettuce 79%) and in motility inhibition (swimming: tetra and cranberry 87%; swarming: tetra 92%, cranberry 94%). It has been shown by molecular docking method that phenolic compounds of plant extracts may be effective in the inhibition of the QS system by binding to the LsrB receptor (tetra: phlorizin and propylgallate) and LuxS enzyme (cranberry: isorhamnetin, tetra: propylgallate) with a higher affinity than AI-2 and S-ribosylhomocysteine substrates in Salmonella serotypes. With these properties, it is understood that cranberry and tetra may have the potential to be used safely as active ingredients in sustainable food packaging production, functional food, food preservative and hygiene applications. Keywords: Ethnobotanical Plants, Salmonella, Quorum Sensing, Quorum Sensing Inhibition, Biofilm, Motility, Quorum Sensing in Food.