Abstract

Quorum sensing (QS) plays a vital role in regulating the virulence factor of many food borne pathogens, which causes severe public health risk. Therefore, interrupting the QS signaling pathway may be an attractive strategy to combat microbial infections. In the current study QS inhibitory activity of quercetin and its anti-biofilm property was assessed against food-borne pathogens using a bio-sensor strain. In addition in-silico techniques like molecular docking and molecular dynamics simulation studies were applied to screen the quercetin’s potentiality as QS inhibitor. Quercetin (80μg/ml) showed the significant reduction in QS-dependent phenotypes like violacein production, biofilm formation, exopolysaccharide (EPS) production, motility and alginate production in a concentration-dependent manner. Synergistic activity of conventional antibiotics with quercetin enhanced the susceptibility of all tested pathogens. Furthermore, Molecular docking analysis revealed that quercetin binds more rigidly with LasR receptor protein than the signaling compound with docking score of -9.17Kcal/mol. Molecular dynamics simulation predicted that QS inhibitory activity of quercetin occurs through the conformational changes between the receptor and quercetin complex. Above findings suggest that quercetin can act as a competitive inhibitor for signaling compound towards LasR receptor pathway and can serve as a novel QS-based antibacterial/anti-biofilm drug to manage food-borne pathogens.

Highlights

  • Food spoilage and biofilm formation by food-borne pathogens are significant problems in the food industry

  • Minimum inhibitory concentration was determined for quercetin against biosensor strain C. violaceum and three test bacterial strains

  • Non-transparent halo zones around the discs represents the inhibition of violacein production, which may be due to specific interference with induced Acyl homoserine lactone (AHL) production

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Summary

Introduction

Food spoilage and biofilm formation by food-borne pathogens are significant problems in the food industry. Even with the modern food preservation techniques, the excessive amount of food lost due to microbial spoilage [1]. Food borne pathogens like Bacillus spp., Pseudomonas spp., Salmonella spp., Campylobacter jejuni and Yersinia enterocolitica were identified to form biofilms [2]. Attachment of these food borne pathogens to the food product or the processing surfaces leads to severe public health risk and economic losses [3]. Several biochemical processes like lipolytic and proteolytic activities associated with food deterioration are regulated by quorum sensing [4]. Microbial activity is considered to be the most common cause of PLOS ONE | DOI:10.1371/journal.pone.0134684 August 6, 2015

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