scholarly journals The impact of the competence quorum sensing system on Streptococcus pneumoniae biofilms varies depending on the experimental model

2011 ◽  
Vol 11 (1) ◽  
pp. 75 ◽  
Author(s):  
Claudia Trappetti ◽  
Luciana Gualdi ◽  
Lorenzo Di Meola ◽  
Prashant Jain ◽  
Cindy C Korir ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Quorum Sensing ◽  
Experimental Model ◽  
Sensing System ◽  
Quorum Sensing System ◽  
The Impact

scholarly journals The LuxS-Dependent Quorum-Sensing System Regulates Early Biofilm Formation by Streptococcus pneumoniae Strain D39

2011 ◽  
Vol 79 (10) ◽  
pp. 4050-4060 ◽  
Author(s):  
Jorge E. Vidal ◽  
Herbert P. Ludewick ◽  
Rebekah M. Kunkel ◽  
Dorothea Zähner ◽  
Keith P. Klugman
Keyword(s):  
Streptococcus Pneumoniae ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Single Copy ◽  
Middle Ear Mucosa ◽  
Transcript Levels ◽  
Content Type ◽  
Sensing System ◽  
Quorum Sensing System

ABSTRACTStreptococcus pneumoniaeis the leading cause of death in children worldwide and forms highly organized biofilms in the nasopharynx, lungs, and middle ear mucosa. TheluxS-controlled quorum-sensing (QS) system has recently been implicated in virulence and persistence in the nasopharynx, but its role in biofilms has not been studied. Here we show that this QS system plays a major role in the control ofS. pneumoniaebiofilm formation. Our results demonstrate that theluxSgene is contained by invasive isolates and normal-flora strains in a region that contains genes involved in division and cell wall biosynthesis. TheluxSgene was maximally transcribed, as a monocistronic message, in the early mid-log phase of growth, and this coincides with the appearance of early biofilms. Demonstrating the role of the LuxS system in regulatingS. pneumoniaebiofilms, at 24 h postinoculation, two different D39ΔluxSmutants produced ∼80% less biofilm biomass than wild-type (WT) strain D39 did. Complementation of these strains withluxS, either in a plasmid or integrated as a single copy in the genome, restored their biofilm level to that of the WT. Moreover, a soluble factor secreted by WT strain D39 or purified AI-2 restored the biofilm phenotype of D39ΔluxS. Our results also demonstrate that during the early mid-log phase of growth, LuxS regulates the transcript levels oflytA, which encodes an autolysin previously implicated in biofilms, and also the transcript levels ofply, which encodes the pneumococcal pneumolysin. In conclusion, theluxS-controlled QS system is a key regulator of early biofilm formation byS. pneumoniaestrain D39.

P. aeruginosa Quorum Sensing System and the Experimental Model of Chronic Respiratory Infection: Scientific Letter

2011 ◽  
Vol 31 (4) ◽  
pp. 981-984
Author(s):  
Meral KARAMAN ◽  
Vahide BAYRAKAL ◽  
Osman YILMAZ ◽  
Müge KİRAY ◽  
H. Alper BAĞRIYANIK ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Experimental Model ◽  
Respiratory Infection ◽  
Scientific Letter ◽  
Sensing System ◽  
Quorum Sensing System ◽  
Chronic Respiratory Infection

scholarly journals Acacia dudgeoni Craib. ex Holl (Mimosaceae): Potential Inhibitor of Biofilm Formation and Quorum Sensing in P. aeruginosa PAO1

2019 ◽  
pp. 1-6 ◽  
Author(s):  
Vincent Ouedraogo ◽  
Issa Karama ◽  
Ablassé Rouamba ◽  
Moussa Compaoré ◽  
Martin Kiendrebeogo
Keyword(s):  
Quorum Sensing ◽  
Virulence Factor ◽  
Biofilm Formation ◽  
Methanol Extract ◽  
Stem Bark ◽  
Significant Inhibition ◽  
Sensing System ◽  
Quorum Sensing System ◽  
The Impact ◽  
Pyocyanin Production

Aims: The study aims to assess the ability of Acacia dudgeoni bark to antagonize quorum sensing system, expression of virulence factor and biofilm formation. Place and Duration of Study: The study was conducted at the Laboratory of Applied Biochemistry and Chemistry (LABIOCA), University Joseph KI-ZERBO between December 2018 to April 2019. Methodology: Methanol extract from A. dudgeoni stem bark, was used for the investigations. The reporters strain Chromobacterium violaceum CV026 and Pseudomonas aeruginosa PAO1 were used to measure the impact of extract on quorum sensing controlled violacein and pyocyanin production. P. aeruginosa PAO1 was used to measure the impact on biofilm formation. Results: At different concentrations (50-400 µg/mL) A. dudgeoni methanol extract quenched the quorum sensing mechanism. Significant inhibition of virulence factor, pyocyanin was recorded (66% of inhibition at 400 µg/mL) without affect negatively the growth of P. aeruginosa PAO1. The formation of biofilm was also affected with a reduction up to 59% at the concentration of 400 µg/mL. Conclusion: The anti-quorum sensing and anti-biofilm properties of this medicinal plant could serve as a source in the developpement of new effective anti- quorum sensing drugs.

#99: Streptococcus pyogenes Utilizes the Peptide-Based Rgg 2/3 Quorum Sensing System During Oropharyngeal Colonization

2021 ◽  
Vol 10 (Supplement_1) ◽  
pp. S10-S10
Author(s):  
Artemis Gogos ◽  
Michael J Federle
Keyword(s):  
Quorum Sensing ◽  
Streptococcus Pyogenes ◽  
Lymphoid Tissue ◽  
Transcriptional Activator ◽  
Rt Pcr ◽  
Sensing System ◽  
Bacterial Rna ◽  
Quorum Sensing System ◽  
Luciferase Reporters

Abstract Background Streptococcus pyogenes is a human-restricted pathogen most often found in the human nasopharynx. Multiple bacterial factors have been found to contribute to persistent colonization of this niche, and many of these factors are important in mucosal immunity and vaccine development. In this work, we infected mice intranasally with transcriptional regulator mutants of the Rgg2/3 quorum sensing (QS) system—a peptide-based signaling system conserved in all sequenced isolates of S. pyogenes. Methods Three-week-old CD1 mice were intranasally infected with ~107 CFU of S. pyogenes strain MGAS315. Calcium alginate throat swabs were used to monitor nasopharyngeal colonization by the bacteria over time. Luciferase reporters used alongside an IVIS camera were able to show quorum sensing activity levels after inoculation into the mouse nose. Bacterial RNA was isolated from the throat of the mice and quantitative RT–PCR was performed on the samples to corroborate the luciferase reporter data. The nasal-associated lymphoid tissue (NALT) was excised and its supernatants were subjected to 32-plex murine cytokine and chemokine analysis (Millipore). Results Deletion of the QS system’s transcriptional activator (Δrgg2) dramatically diminished the percentage of colonized mice. Deletion of the transcriptional repressor (Δrgg3) increased the percentage of colonized mice compared with wild type. Stimulation of the QS system using synthetic pheromones prior to inoculation did not significantly increase the percentage of animals colonized, indicating that activity of the QS system is responsive to conditions of the host nasopharynx. Mice inoculated with QS-dependent luciferase reporters were subjected to in vivo imaging and showed activation within 1 hour. Bacterial RNA extracted directly from oropharyngeal swabs and evaluated by quantitative RT–PCR subsequently confirmed QS upregulation within 1 hour of inoculation. In the nasal-associated lymphoid tissue (NALT), a muted inflammatory response to the Δrgg2 bacteria suggests that their rapid elimination fails to elicit the previously characterized response to intranasal inoculation of GAS. Conclusions Deletion of the Rgg2 transcriptional activator of the Rgg 2/3 quorum sensing system eliminates colonization of the murine nasopharynx and changes the transcriptional profile of the bacteria in this niche. An existing small-molecule inhibitor of the Rgg2/3 system was unable to inhibit QS activation in vivo, likely due to the suboptimal achievable doses; however, results of our study indicate inhibition of QS may diminish the oropharyngeal colonization of S. pyogenes and argue for further development.

Investigating the Quorum Sensing System in Halophilic Bacteria

2015 ◽  
pp. 189-207 ◽  
Author(s):  
Tommonaro Giuseppina ◽  
Abbamondi Gennaro Roberto ◽  
Toksoy Oner Ebru ◽  
Nicolaus Barbara
Keyword(s):  
Quorum Sensing ◽  
Halophilic Bacteria ◽  
Sensing System ◽  
Quorum Sensing System

scholarly journals Inhibition of exoprotease production in Aeromonas hydrophila by rhizome extract of temu lawak (Curcuma xanthorrhiza (Roxb.)

2006 ◽  
Vol 4 (2) ◽  
pp. 45-54
Author(s):  
UMI LESTARI ◽  
ARTINI PANGASTUTI ◽  
ARI SUSILOWATI
Keyword(s):  
Quorum Sensing ◽  
Ethyl Acetate ◽  
Aeromonas Hydrophila ◽  
Ethanol Extract ◽  
Homoserine Lactone ◽  
Sensing System ◽  
Development Of Resistance ◽  
Quorum Sensing System ◽  
Assay Result ◽  
Curcuma Xanthorrhiza

Conventional treatment of infectious diseases is based on compounds that kill or inhibit the growth of bacteria. A major concern with this approach is the frequent development of resistance to antimicrobial compounds. The discovery of communication (quorum sensing system) regulating bacterial virulence opens up ways to control certain bacterial infectious without interfering the growth. The fish pathogen Aeromonas hydrophila produces quorum sensing signal, NButanoyl-L-Homoserine Lactone (C4-HSL). C4-HSL regulates exoprotease synthesis, a virulence factor of A. hydrophila. Expression of exoprotease can be blocked by using quorum sensing inhibitor. The purpose of this study was to investigate the inhibiting effect of Curcuma xanthorrhiza (Roxb.) extract to exoprotease production of A. hydrophila. Extraction was conducted by using n-hexane, ethyl acetate and ethanol. The qualitative exoprotease assay result showed that n-hexane extract of C. xanthorrhiza had not effect on growth and exoprotease production of A. hydrophila. Meanwhile, 4% of ethyl acetate and ethanol extract of C. xanthorrhiza can inhibit exoprotease production without affecting A. hydrophilla growth. The quantitative exoprotease assay result showed that 4% of ethyl acetate and ethanol extract can inhibit the exoprotease production by 93,9% and 95,6%. The growth of A. hydrophila was not affected by this extract.

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