Antiquorum Sensing and Antimicrobial Activity of Natural Agents with Potential Use in Food

Abstract

Quorum sensing (QS) is a bacterial communication mechanism that depends on population density. QS inhibitory activity of four bioactive agents and two essential oils was evaluated using the bacteria model Chromobacterium violaceum.On the other hand, antimicrobial activity was tested using two foodborne pathogens, Listeria monocytogenes and Escherichia coli. Agents were able to inhibit the violacein production, being tea tree and rosemary more effective than propolis and pollen, and resveratrol more effective than pomegranate. Tea tree and rosemary essential oils, applied at 0.5 microlt/mL, reduced violacein production by more than 80%. In order to evaluate whether the inhibition of violacein production owed to the microbial growth reduction or acylated homoserine lactone inhibition, the antimicrobial activity was analyzed using C. violaceumas indicator. None of the tested agents showed antimicrobial activity at the minimal QS inhibitory concentration. Agents showed varying degrees of antibacterial activity against pathogens. Tea tree and rosemary resulted more effective than the others. These essential oils showed bacteriostatic effect on pathogen counts at low concentrations (0.5-1 microlt/ mL). When they were applied at concentrations higher than 2 microlt/mL, bactericidal effect was observed against E. coli and L. monocytogenes. These findings strongly suggest that these agents have potential to be good preservatives because of anti-QS capacity and antimicrobial properties.