Diallyl disulfide from garlic oil inhibits Pseudomonas aeruginosa virulence factors by inactivating key quorum sensing genes
Garlic oil can disrupt the quorum sensing (QS) pathways of the opportunistic pathogen Pseudomonas aeruginosa; however, the underlying mechanisms for this effect are unclear. Diallyl disulfide (DADS) is one of the most abundant sulfur-containing compounds in garlic oil. This study investigated the effects of DADS on the growth, virulence factor production (elastase, pyocyanin, biofilm, and swarming motility), and essential gene expression of P. aeruginosa PAO1, particularly as they apply to QS and virulence. DADS at 1.28 mg/mL did not affect P. aeruginosa PAO1 growth, although it decreased elastase and pyocyanin production, biofilm formation, and swarming motility. Each of these phenomena is regulated by the three QS systems of P. aeruginosa PAO1 (las, rhl, and pqs). Real-time q-PCR revealed that DADS down-regulated the transcription levels of several important QS genes (lasI, lasR, rhlI, rhlR, pqsA, and pqsR) in the three systems. Furthermore, the transcription levels of QS-regulated virulence genes were also down-regulated. The lasB gene, encoding LasB elastase, is co-regulated by the las, rhl, and pqs systems, and thus the down-regulation of genes across the three systems further down-regulated lasB. Additionally, phzM (encoding pyocyanin), pslB (responsible for the production of a biofilm matrix polysaccharide), and chiC (encoding chitinase) were positively activated by LasR, and a decrease in lasR transcription further down-regulated the transcription of phzM, pslB, and chiC. Hence, DADS inhibits P. aeruginosa PAO1 virulence factors by inactivating the transcription of key genes across three different QS systems.
KeywordsDiallyl disulfide Garlic oil Pseudomonas aeruginosa PAO1 Virulence factors
We thank Professor Zhang Lixin and Dai Huanqin of the CAS Key Laboratory of Pathogenic Microbiology and Immunology, Beijing, China, for their presenting strains of P. aeruginosa PAO1. We are obliged to the anonymous reviewers of Applied Microbiology and Biotechnology for their constructive comments.
This study was supported by grants from the Nature Science of Foundation of China (no. 31500113), Guangdong Provincial Nature Science of Foundation (no. 2016A030313800), Guangzhou Municipal Science and Technology Research Project (no. 201607020020), and Guangdong Provincial Science and Technology Project (no. 2013B010102014).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This manuscript represents original research performed by our group. It has not been submitted elsewhere, and it is not under consideration in any other journal. This article does not contain any studies with human participants or animals performed by any of the authors. All the authors have seen the manuscript and approved its submission to Applied Microbiology and Biotechnology.
- Bjarnsholt T, Jensen PØ, Rasmussen TB, Christophersen L, Calum H, Hentzer M, Hougen HP, Rygaard J, Moser C, Eberl L, HØiby N, Givskov M (2005) Garlic blocks quorum sensing and promotes rapid clearing of pulmonary Pseudomonas aeruginosa infections. Microbiology 151:3873–3880. https://doi.org/10.1099/mic.0.27955-0 CrossRefPubMedGoogle Scholar
- Colvin KM, Irie Y, Tart CS, Urbano R, Whitmey JC, Ryder C, Howell PL, Wozniak DJ, Parsek MR (2012) The Pel and Psl polysaccharides provide Pseudomonas aeruginosa structural redundancy within the biofilm matrix. Environ Microbiol 14:1913–1928. https://doi.org/10.1111/j.1462-2920.2011.02657.x CrossRefPubMedGoogle Scholar
- Déziel E, Gopalan S, Tampakaki AP, Lépine F, Padfield KE, Saucier M, Xiao GP, Rahme LG (2004) The contribution of MvfR to Pseudomonas aeruginosa pathogenesis and quorum sensing circuitry regulation: multiple quorum sensing-regulated genes are modulated without affecting lasRI, rhlRI or the production of N-acyl-L-homoserine lactones. Mol Microbiol 55:998–1014. https://doi.org/10.1111/j.1365-2958.2004.04448.x CrossRefGoogle Scholar
- Diggle SP, Winter K, Chhabra SR, Worrall KE, Cámara M, Williams P (2003) The Pseudomonas aeruginosa quinolone signal molecule overcomes the cell density-dependency of the quorum sensing hierarchy, regulates rhl-dependent genes at the onset of stationary phase and can be produced in the absence of LasR. Mol Microbiol 50:29–43. https://doi.org/10.1046/j.1365-2958.2003.03672.x CrossRefPubMedGoogle Scholar
- Galdino AC, Viganor L, Ziccardi M, Nunes AP, Santos KRN, Branquinha MH, Santos ALS (2017) Heterogeneous production of proteases from Brazilian clinical isolates of Pseudomonas aeruginosa. Enferm Infecc Microbiol Clin 35(10):630–637. https://doi.org/10.1016/j.eimce.2016.06.004 CrossRefPubMedGoogle Scholar
- Harjai K, Kumar R, Singh S (2010) Garlic blocks quorum sensing and attenuates the virulence of Pseudomonas aeruginosa. FEMS Immunol Med Microbiol 58:161–168. https://doi.org/10.1111/j.1574-695X.2009.00614.x
- Jakobsen TH, Gennip MV, Phipps RK, Shanmugham MS, Christensen LD, Alhede M, Skindersoe ME, Rasmussen TB, Friedrich K, Uthe F, Jansen PØ, Moser C, Nielsen KF, Eberl L, Larsen TO, Tanner D, HØiby N, Bjarnsholt T, Givskov M (2012) Ajoene, a sulfur-rich molecule from garlic, inhibits genes controlled by quorum sensing. Antimicrob Agents Ch 56(5):2314–2325. https://doi.org/10.1128/AAC.05919-11 CrossRefGoogle Scholar
- Karatuna O, Yagci A (2010) Analysis of quorum sensing-dependent virulence factor production and its relationship with antimicrobial susceptibility in Pseudomonas aeruginosa respiratory isolates. Clin Microbiol Infect 16:1770–1775. https://doi.org/10.1111/j.1469-069.2010.03177.x CrossRefPubMedGoogle Scholar
- Ko JW, Park SH, Shin NR, Shin JY, Kim JW, Shin IS, Moon C, Heo JD, Kim JC, Lee IC (2017) Protective effect and mechanism of action of diallyl disulfide against acetaminophen-induced acute hepatotoxicity. Food Chem Toxicol 109:28–37. https://doi.org/10.1016/j.fct.2017.08.029 CrossRefPubMedGoogle Scholar
- Latifi A, Foglino M, Tanaka K, Williams P, Lazdunski A (1996) A hierarchical quorum-sensing cascade in Pseudomonas aeruginosa links the transcriptional activators LasR and RhlR (VsmR) to expression of the stationary-phase sigma factor RpoS. Mol Microbiol 21:1137–1146. https://doi.org/10.1046/j.1365-2958.1996.00063.x CrossRefPubMedGoogle Scholar
- Ma L, Jackson KD, Landry RM, Parsek MR, Wozniak DJ (2006) Analysis of Pseudomonas aeruginosa conditional Psl variants reveals roles for the Psl polysaccharide in adhesion and maintaining biofilm structure post attachment. J Bacteriol 188:8213–8221. https://doi.org/10.1128/JB.01202-06 CrossRefPubMedPubMedCentralGoogle Scholar
- Pearson JP, Gray KM, Passador L, Tucker KD, Eberhard A, Iglewski BH, Greenberg EP (1994) Structure of the autoinducer required for expression of Pseudomonas aeruginosa virulence genes. Proc Natl Acad Sci U S A 91:197–201. https://doi.org/10.1073/pnas.91.1.197 CrossRefPubMedPubMedCentralGoogle Scholar
- Rasmussen TB, Bjarnsholt T, Skindersoe ME, Hentzer M, Kristoffersen P, Köte M, Nielsen J, Eberl L, Givskov M (2005) Screening for quorum-sensing inhibitors (QSI) by use of a novel genetic system. the QSI selector J Bacteriol 187(5):1799–1814. https://doi.org/10.1128/JB.1875.5.1799-1814.2005 CrossRefPubMedGoogle Scholar
- Smyth AR, Cifelli PM, Ortori CA, Righetti K, Lewis S, Erskine P, Holland ED, Givskov M, Williams P, Cámara M, Barrett DA, Knox A (2010) Garlic as an inhibitor of Pseudomonas aeruginosa quorum sensing in cystic fibrosis—a pilot randomized controlled trial. Pediatr Pulm 45:356–362. https://doi.org/10.1002/ppul.21193 Google Scholar
- Stover CK, Pham XQ, Erwin AL, Mizoguchi SD, Warrener P, Hickey MJ, Brinkman FSL, Hufnagle WO, Kowalik DJ, Lagrou M, Garber RL, Goltry L, Tolentino E, Westbrock-wadman S, Yuan Y, Brody LL, Coulter SN, Folger KR, Kas A, Larbig K, Lim R, Smith K, Spencer D, Wong GKS, Wu Z, Paulsen IT, Reizer J, Saier MH, Hancock REW, Lory S, Olson MV (2000) Complete genome sequence of Pseudomonas aeruginosa PAO1, an opportunistic pathogen. Nature 406:959–964. https://doi.org/10.1038/35023079 CrossRefPubMedGoogle Scholar