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 Non-Native Peptides Capable of Pan-Activating the agr Quorum Sensing System across Multiple Specificity Groups of Staphylococcus epidermidis

2021 ◽  
Author(s):  
Korbin H. J. West ◽  
Wenqi Shen ◽  
Emma L. Eisenbraun ◽  
Tian Yang ◽  
Joseph K. Vasquez ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Staphylococcus Epidermidis ◽  
Sensing System ◽  
Quorum Sensing System ◽  
Native Peptides

#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.

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.

scholarly journals Quorum-Sensing System and Stationary-Phase Sigma Factor (rpoS) of the Onion Pathogen Burkholderia cepacia Genomovar I Type Strain, ATCC 25416

2003 ◽  
Vol 69 (3) ◽  
pp. 1739-1747 ◽  
Author(s):  
Claudio Aguilar ◽  
Iris Bertani ◽  
Vittorio Venturi
Keyword(s):  
Quorum Sensing ◽  
Stationary Phase ◽  
Sigma Factor ◽  
Burkholderia Cepacia ◽  
Type Strain ◽  
Plant Pathogens ◽  
Signal Molecules ◽  
Strain Atcc ◽  
Sensing System ◽  
Quorum Sensing System

ABSTRACT Bacterial strains belonging to Burkholderia cepacia can be human opportunistic pathogens, plant pathogens, and plant growth promoting and have remarkable catabolic activity. B. cepacia consists of several genomovars comprising what is now known as the B. cepacia complex. Here we report the quorum-sensing system of a genomovar I onion rot type strain ATCC 25416. Quorum sensing is a cell-density-dependent regulatory response which involves the production of N-acyl homoserine lactone (HSL) signal molecules. The cep locus has been inactivated in the chromosome, and it has been shown that CepI is responsible for the biosynthesis of an N-hexanoyl HSL (C6-HSL) and an N-octanoyl HSL (C8-HSL) and that the cep locus regulates protease production as well as onion pathogenicity via the expression of a secreted polygalacturonase. A cep-lacZ-based sensor plasmid has been constructed and used to demonstrate that CepR responded to C6-HSL with only 15% of the molar efficiency of C8-HSL, that a cepR knockout mutant synthesized 70% less HSLs, and that CepR responded best towards long-chain HSLs. In addition, we also report the cloning and characterization of the stationary-phase sigma factor gene rpoS of B. cepacia ATCC 25416. It was established that quorum sensing in B. cepacia has a negative effect on rpoS expression as determined by using an rpoS-lacZ transcriptional fusion; on the other hand, rpoS-null mutants displayed no difference in the accumulation of HSL signal molecules.

The Virulence Associated fsr Quorum Sensing System Play Key Roles in Enterococcus Faecalis

2021 ◽  
Author(s):  
Jinglin Yue ◽  
Pengcheng Du ◽  
Mingxi Hua ◽  
Xinzhe Liu ◽  
Ang Duan ◽  
...  
Keyword(s):  
Urinary Tract ◽  
Quorum Sensing ◽  
Genome Size ◽  
Enterococcus Faecalis ◽  
Genomic Analysis ◽  
Antibiotic Prescribing ◽  
Human Origins ◽  
Sensing System ◽  
Quorum Sensing System ◽  
Tract Infections

Abstract Enterococcus faecalis, a major nosocomial pathogen, has become a top leading cause of hospital-acquired infections including urinary tract infections, endocarditis and bacteremia. It is important to study the epidemiology and virulence characteristics of E. faecalis isolates in order to tailor infection prevention and antibiotic prescribing. In this study, comparative genomic analysis was conducted on 537 isolates from different human origins. The isolates from bloodstream and intra-abdominal lining had the largest and smallest average genome size respectively, while the isolates from open natural orifices (gastrointestinal tract, urinary tract, respiratory tract, wound and eye) had medium average genome size. The phylogenetic relationships were expounded that the strain isolation niche is uncorrelated with strain phylogeny. Six clonal complexes generally appeared in different isolation sources. Furthermore, genomic analysis revealed differences at the accessory genome, the functions of different genes mainly pointed to the virulence, drug resistance and metabolism of E. faecalis. Interestingly, fsr quorum sensing system genes affecting biofilm formation had a highest proportion in the blood-derived strains. This study showed the genomic characteristics of different human origins and suggested that fsr quorum-sensing system maybe a contributing factor of bacteremia due to E. faecalis infection.

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