|WANG, RENJIE - Chongqing University
|VEGA, PABLO - Purdue University
|XU, YI - Chongqing University
|IRUDAYARAJ, JOSEPH - Purdue University
Submitted to: Biomedical Materials Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2018
Publication Date: 3/23/2018
Citation: Wang, R., Vega, P., Xu, Y., Chen, C., Irudayaraj, J. 2018. Exploring the anti-quorum sensing activity of a D-limonene nanoemulsion for Escherichia coli O157:H7. Biomedical Materials Research. https://doi.org/10.1002/jbm.a.36404.
Interpretive Summary: Quorum sensing (QS), bacterial cell-to-cell communication, is involved in bacterial disease processes and controls a wide variety of behaviors such as bacterial motility, biofilm (groups of microorganisms attached to each other and to a surface and embedded within an extracellular polymeric matrix) formation and virulence (potential to cause disease) gene expression. Compounds that can inhibit QS are thought to have high potential to be effective antibacterial/anti-infectious treatments that would also prevent the ability of the bacterium to acquire resistance to antibiotics. A special process was developed to make D-limonene (natural compound found in citrus) more soluble. The anti-QS property was evaluated on E. coli biofilm formation using microscopy and dye binding, bacterial swimming and swarming ability, and QS gene expression. The results showed the potential of D-limonene to be used as non-antibiotic antibacterial agents.
Technical Abstract: Escherichia coli O157:H7 (E. coli O157:H7) is an important food-borne pathogen implicated in gastrointestinal illness and food-borne outbreaks. There is a need to develop treatment strategies for E. coli O157:H7 that do not involve the use of antimicrobials to which the pathogen can develop resistance. Inhibiting quorum sensing (cell-to-cell communication) is a promising strategy for developing effective treatment strategies to combat pathogenicity of E. coli O157:H7. D-limonene has been demonstrated to possess antimicrobial activity, but its anti-quorum-sensing (anti-QS) potential has not been studied systematically. In this study, a D-limonene nanoemulsion was developed by using a spontaneous emulsification method and its effects on QS-regulated properties of E. coli O157:H7 were studied. Treatment with D-limonene nanoemulsion inhibited E. coli O157:H7 biofilm formation through the suppression of curli and extracellular polymeric substance (EPS) production without inhibiting cell growth, and it decreased swimming and swarming ability. Further analyses showed that D-limonene nanoemulsion interfered with AI-2 communication and repressed the expression of curli related genes and AI-2 importer genes in E. coli O157:H7. These results revealed the anti-QS potential of D-limonene nanoemulsion, which may potentially contribute to preventing E. coli O157:H7 infection by disrupting quorum sensing with a low probability of developing resistance.