Science topic

Quorum Sensing - Science topic

A phenomenon where microorganisms communicate and coordinate their behavior by the accumulation of signaling molecules. A reaction occurs when a substance accumulates to a sufficient concentration. This is most commonly seen in bacteria.
Questions related to Quorum Sensing
  • asked a question related to Quorum Sensing
Question
2 answers
If the compound shows growth inhibition of C. violaceum, can I still proceed to determine the anti-quorum sensing effects? How can I quantify the production of violacein production?
Relevant answer
Answer
There are a few other ways to show the anti-QS effect of a molecule. The CV strain makes use of short-chain AHLs (C4- and C6 AHLs) for QS. You can also try using the Agrobacterium tumefaciens NTL4 or NT1 reporter strain which detects the presence of long-chain AHLs (C8- and C-12 AHLs). The latter contains a plasmid that induces the expression of the B-Gal gene (due to the presence of AHL molecules) resulting in the hydrolysis of X-Gal on a solid medium, producing light-blue colored colonies or bacterial growth. While in the absence of this enzyme (no QS as a result of no or low concentration of AHL molecules), the colonies appear white in color. You can also quantify this activity by extracting AHLs from your culture, then inducing NTL4 cells with the isolated AHLs, and performing a B-galactosidase assay to determine the activity of B-gal produced as a result of induction by the AHL molecules. Thus, you can detect QS by the virtue of AHL production through the B-gal activity.
For more reference, you can read these 2 articles published by my colleagues Dr. Sunil Kumar Bose and Dr. Karuna Sharma.
Terpinen-4-ol attenuates quorum sensing regulated virulence factors and biofilm formation in Pseudomonas aeruginosa.
Sustained release of Zingerone from polymeric nanoparticles: An anti-virulence strategy against Pseudomonas aeruginosa.
Good luck!
  • asked a question related to Quorum Sensing
Question
4 answers
I would like to know if there are any commercially available rapid detection kits for quorum-sensing N-acyl homoserine lactone (AHLs). Would like a recommendation of a product that is commerically available with a relatively high degree of accuracy. Thanks.
Relevant answer
Answer
Detection of Quorum-Sensing Molecules for Pathogenic Molecul...
  • asked a question related to Quorum Sensing
Question
8 answers
I want to find a quorum sensing inhibitor from plant extracts.
Klebsiella pneumoniae, Moraxella catarrhalis, Staphylococcus aureus, and Streptococcus pneumoniae.
I looked for these strains available for purchase;
Chromobacteirum violaceum NCTC13278 (CV026)
Vibrio campbellii ATCC BAA-1116, 1117, 1118 (BB-120, 170, 886)
Are these strains commonly used?
Thanks.
Relevant answer
Answer
If you are going to screen the plant bioactive for quorum sensing activities means, go with Gram-negative bacterial pathogens.
The Gram-negative bacterial pathogens are ideal for quorum sensing inhibition studies. Because the Gram-negative bacterial pathogens regulates their virulence factors production through signal molecules called acyl homoserine lactone (AHL). Generally, these AHL molecules go and bind with the receptor protein and these complex triggers virulence gene expression. The chemical compounds (including plant bioactive) may act as the analogous for the receptor protein. Therefore, it competitively binds with the AHL and prevents the formation of AHL-receptor protein complex. This leads to prevent the virulence gene expression. So, the possibility is many of the plant or natural compounds can act as the analogous for the receptor protein of Gram-negative bacteria.
Further, the QS system in Gram-negative bacterial pathogens such as Pseudomonas aeruginosa, Serratia marcescens, Acinetobacter baumannii, Vibrio harveyi, Aeromonas hydrophila etc were studied well.
But, the Gram-positive bacterial pathogens were mainly reported for their biofilm formation. More, only QS contributed meagre in virulence factors production in Gram-positive bacterial pathogens. The Gram-positive bacterial pathogens are most apt for biofilm inhibition studied and not for QS inhibition. Furthermore, the QS system in Gram-positive bacterial pathogens is totally different from Gram-negative bacterial pathogens.
More, the biofilm is the important virulence factors for bacterial pathogens. The biofilm formation in many Gram-negative bacterial pathogens are also comes under QS system. In contrast, the biofilm formations in Gram-positive bacterial pathogens are mostly not related to QS system. Only some Gram-positive bacterial pathogens are controlling their biofilm under QS.
So, my opinion is go with Gram-negative bacterial pathogens especially Acinetobacter baumannii. Because, now a days these pathogens are emerge as the global threat. The WHO categorized these bacterial pathogens as the critical pathogen, means need to find effective drug to prevent their infections. If you like to screen the plant bioactive for mainly biofilm inhibition means go with Gram-positive bacterial pathogens.
Also, my another opinion is mostly don’t go with the Chromobacterium violaceum for screening the plant bioactives. Because, after scrutinize the compounds, you need to go with the other virulent Gram-negative bacterial pathogens for assessing the activity (Note that the C. violaceum is not pathogen, it is only a marker strain and soil bacterium). The scrutinized compounds mostly will not work against another virulent Gram-negative bacterial pathogens. Because, the AHL signal molecules are vary in every Gram-negative bacterial pathogens. So, the scrutinized compounds by the C. violaceum may not work with particular Gram-negative bacterial pathogens. Therefore, my suggestion is if you have limited plant extracts or bioactive compounds means go directly with the screening of the compounds or extracts for their biofilm inhibition against your selected Gram-negative bacterial pathogens. It will be the effective way and give the ideal QS inhibitors against particular Gram-negative bacterial pathogens.
Thank You.
  • asked a question related to Quorum Sensing
Question
7 answers
Looking at the various CoV genomes, there are peptides/small proteins, aside from ORF1/2 on the genome, of which functions are unknown. These could circulate and in theory, once in abundance, induce allosteric changes in membrane bound proteins to induce viral shedding alike to bacteriophage Q-sense.
Relevant answer
Answer
Interesting question ! But I don't think they quorum sense because there is no auto inducer like molecule or peptide found till date in their genome.
But Silpe, J. E. & Bassler, B. L. 2019 and Xiaolong et al., 2020 found that there is link between quorum sensing signals and viral growth which means secondary infection in viral infections would lethal especially in case of COVID.
best wishes
VK
  • asked a question related to Quorum Sensing
Question
8 answers
Hello,
I am researching into how bacteria communicate.
What I've found is that they use quorum-sensing*, and electrical signals**.
I've also come across the ability to "speak and listen"***, but I wonder if there are more ways that they use.
Thank you for your answers!
Relevant answer
Answer
Bacteria communicate with one another using chemical signal molecules. ... This process, termed quorum sensing, allows bacteria to monitor the environment for other bacteria and to alter behavior on a population-wide scale in response to changes in the number and/or species present in a community.
  • asked a question related to Quorum Sensing
Question
5 answers
The question might be a little bit stupid but I haven't found direct answer yet. Maybe anyone can explain it.
Why AHL molecules do not induct the activation of quorum-sensing genes inside the cells where they were synthesized? I mean, they might bound with transcription factors without leaving the cell, at least for gram-negative bacteria.
Relevant answer
Answer
That is because quorum-sensing is threshold-dependant: every cell produce an amount of molecules that cannot trigger it inside the same aforementioned cell. So, basically, if a lot of bacteria produce those molecules that means also that their intake will exceed the threshold value and cause the phenomenon to be activated. It is a fine and logic way for bacteria to communicate the size of the microbial population. Hope that helped
  • asked a question related to Quorum Sensing
Question
2 answers
Quorum sensing, a type of bacterial interaction is found to be involved in the development of antibiotic resistance by the pathogenic microorganisms. I want to find if a non resistant bacteria can develop resistance to the same antibiotics while cultured together with the resistant microbes and does it involve the quorum sensing interactions between the two different species of microbes. Antibiotic resistance is found to take place by various ways like; efflux pump, chemical modifications and also by modification of drug targeting genes.
Therefore, i want to work on whether resistance could be developed by involvement of quorum sensing in the modification of drug targeting gene, for that I request to suggest protocols for the process of investigating inter-species quorum sensing involvement in drug resistance development by the modification of genes of bacteria targeted by the antibiotics.
Thank you
Relevant answer
Answer
Quorum sensing is mediated by QS-autoinducers (AI). Most of them are known. Just take AI of various types (I-IV) and work with them, trying to induce resistance. However, it doesn't work that way, I think. Often, direct damaging contact of the antibiotic`s molecule with the molecular target is necessary for resistance development. QS is likely to be involved indirectly. For example, "some hydrophobic QS-autoinducers such as PQS are trafficked between cells via membrane vesicles. In this case, the peptide’s (antimicrobial peptides) membrane-permeabilizing action releases accumulated PQS molecules, which can trigger the expression of the virulence genes associated with quorum sensing" (doi:10.3389/fmicb.2019.01160)
Nevertheless. you can study one of the existing editions of QS: Methods and Protocols, available at https://link.springer.com/book/10.1007%2F978-1-4939-7309-5
  • asked a question related to Quorum Sensing
Question
4 answers
Is there any explanation for this that why the same specie of bacteria is qourum sensing positive when it is isolated from clinical sample but when we isolate that specie from marine sediment, it is qourum sensing negative? what can be the possible reason?
Relevant answer
Answer
QS systems are strain dependent. Sometimes, but not always, this fact is related to the acquisition of the QS genes through horizontal transfer.
  • asked a question related to Quorum Sensing
Question
9 answers
Curious about what level of existence or non-existence (however one may qualify those two terms, or the two listed in the title ('living matter' or 'non-living matter') can collapse the wave function, so as to help research on understanding the "mesocopic" divide between the quantum (microscopic) and classical (macroscopic) realms of physics.
Here are some articles I've ran across/am using for my last paper in my undergraduate work:
Relevant answer
Answer
It has to be a screen that does not take energy from the particles being diffracted. If it does take any energy then the pattern is lost. In that case it is also possible to tell which slit a particle went through (because you can in principle detect where the energy appears). When the screen is massive enough then no energy exchange occurs - like an elastic ball bouncing from the earth.
  • asked a question related to Quorum Sensing
Question
1 answer
Ethyl acetate is a commonly used solvent for extraction of AHLs. However when it comes to storing them, it is generally stored in acetonitrile after evaporating the solvent. Is it alright if the extracted AHLs are stored in the acidified ethyl acetate (0.2% glacial acetic acid)?
Relevant answer
Answer
Hello Ashish,
We are using pure grade methanol for storing wide range of AHLs in our LAB, at -20 °C.
Best,
S.S.A. SHAH
  • asked a question related to Quorum Sensing
Question
3 answers
Theoretically, using a mutant strain of V. harveyi which is only capable of producing AI-2, bioluminescence was induced upon addition of a compound. On the other hand, with wild-type V. harveyi, AI-2 synthase was downregulated. How was it possible?
Relevant answer
Answer
Bioassay using Vibrio harveyi BB strain may be less reproducible depending on the sample and microbial state. Therefore, it is recommended to proceed simultaneously with bioassay and other analytic methods (e.g., LC-FID or LC-UV) to detect AI-2 or DPD.
  • asked a question related to Quorum Sensing
Question
5 answers
As a chemist, I realy could not distenguish the diffrence between them. And also I wonder what the advantage of this knid of assay comparing to the classical MIC test.
Relevant answer
Answer
QS is cell-to-cell communication protocol by which bacteria respond to its local environment, i.e., pathogenic activation, resistance to antibiotics etc. QS carried out when signal molecule like acyl homoserine lactone (AHL) binds to LasR protein of the QS system. Enzyme mediated disruption of this process is called QQ where enzyme inhibits signal molecules through variety of process. For example, lactonase inactivate the process by lysing lactone ring of AHL molecule while acylase cut off its acylase chain.
  • asked a question related to Quorum Sensing
Question
2 answers
RhlR is a quorum sensing regulator in Pseudomonas aeruginosa. There are so many LuxR type quorum regulators have been crystallized and structures available in PDB. I wondering why the crystal structure of RhlR is not available till date ?
Relevant answer
Answer
(1) Nobody has solved the structure yet or (2) somebody has solved the structure but has not made it available to the public.
  • asked a question related to Quorum Sensing
Question
3 answers
Hello everybody, we are working on the eradication of Helicobacter pylori and inhibition of its biofilm. We are looking for the suggestions that what compounds would be better to use against H. pylori to inhibit the quorum sensing.
Relevant answer
Answer
Enzymes like lactonases, acylases which target the AHLs, various oxidoreductases, use of antibiotics, synthetic molecules that sequester the signal can be used. (Interference With Quorum-Sensing Signal Biosynthesis as a Promising Therapeutic Strategy Against Multidrug-Resistant Pathogens by Martinez et al., 2019)
Also some methanol extracts of roots of Albiza schimperiana (ASRM), Solanum torvum and petroleum ether extract of seed of Justica schimperiana (JSSP) and many more have been used and good results have been seen.
  • asked a question related to Quorum Sensing
Question
2 answers
I am working on quorum quenching activity of quenching enzymes specifically produced by Gram negative bacteria against S. aureus quorum sensing activity. The only way i found for this is using a S. aureus 8325-4 (pSB2035) transformant strain. Please, anyone if knows a better alternative, share with me. Thanks
Relevant answer
Answer
Dear Miguel,
Thank you very much for you kind, valuable suggestion. However, to the best of my knowledge we can use your method of evaluation for Gram-negative bacteria not for Gram-positives' particularly S. aureus. Thanks
  • asked a question related to Quorum Sensing
Question
3 answers
Hi, I'm looking for anyone or any institution that may possibly provide me Chromobacterium violaceum CV026 and Pseudomonas aeruginosa PAO1 strains to be used for a research on quorum sensing? And have it arranged to be shipped to the Philippines? Thanks a lot!
Relevant answer
Answer
We have Chromobacterium violaceum isolated from Tripura soil.
  • asked a question related to Quorum Sensing
Question
6 answers
Hello
I need a help here. I am currently working on inhibition of quorum sensing in Chromobacterium violaceium MTCC 2656.but my culture doesnt produce the purple pigment I am worried if the addition of commercially available long chain AHL molecules will help . how i need to go about this as my main study is on the inhibition of the pigment. please share your valuable suggestions
Thank you in advance
Relevant answer
Answer
Recently, violacein biosynthesis from C. violaceum in the presence of antibiotics was studied ( Liu et al., 2013 ). Violacein production was enhanced by 25%
using sub-inhibitory concentrations of amikacin (1/4 MIC), erythromy-
cin (1/8 MIC), gentamicin (1/2 MIC), kanamycin (1/6 MIC) and tetracy-
cline (1/16 MIC) without bacterial growth inhibition.
.
  • asked a question related to Quorum Sensing
Question
3 answers
Does anyone know where I can buy S-ribosyl homocysteine or know of a company or university I can send my sample to for LuxS inhibition studies?
Relevant answer
Answer
PubChem
Data deposited in or computed by PubChem
  • asked a question related to Quorum Sensing
Question
1 answer
My protein and inhibitors, give different trends in MST data. Fnorm either it is in upward trend or downward trend. What does that mean ? can we define the inhibition level or the pattern with this data ?
  • asked a question related to Quorum Sensing
Question
4 answers
Is there a way to control the quorum sensing to increase the cfu at the end of fermentation, when the percentage of residual sugar is between 0 and 1?
Relevant answer
Answer
I suggest you to read the following
  • asked a question related to Quorum Sensing
Question
5 answers
Quorum sensing- Signalling molecule- Homoserine lactones-Inhibitors.
Relevant answer
  • asked a question related to Quorum Sensing
Question
2 answers
i have laboratory work related to the quorum sensisng
Relevant answer
Answer
Autoinducer Bioassay Details of the method is described in this paper
  • asked a question related to Quorum Sensing
Question
9 answers
I want to test whether the AI-2 produced by bacteria A impact the growth of bacteria B. I want to extract AI-2 but remove proteins, sugars and others from culture broth that might also stimulate bacterial growth. The extract does not need to be pure compound, but it is better to remove proteins and sugars from broth.
  • asked a question related to Quorum Sensing
Question
4 answers
I would appreciate your feedback on this issue. I am interested in evaluating the presence and subsequently quantifying AI-2 molecules in some bacterial cultures that I am working with. So, I would like to ask from those of you who are familiar with this topic to bring some insights of different approaches. For example, are there any culture media that I could use to detect it, is qPCR for LuxS enough, would HPLC work, or have you done any other techniques that gave reliable results?? Thank you in advance for your time!
Relevant answer
Answer
I think the best method is HPLC-MS-MS. I tried to quantify C4 and C12-HSL of Pseudomonas aeruginosa and it worked w
  • asked a question related to Quorum Sensing
Question
6 answers
Dear RG members
I like to discuss with you the recent advances on the quorum sensing and quorum quenching, specialy in Pseudomonas species.
Thanks for the discussion
Relevant answer
Answer
Recent and extraordinary advances in our understanding of the genetics, genomics, biochemistry, and signal diversity of QS is helping researchers to understand the connections between QS and bacterial sociality; a foundation that places us at the beginning of a new era in which researchers will be able to work towards new medicines to treat devastating infectious diseases, and use bacteria to understand the biology of sociality.
Bassler and colleagues have found that bacteria lacking RhlI, which are therefore unable to synthesize the C4-HSL autoinducer, still secrete a molecule capable of activating RhlR. The researchers do not yet know what this molecule is, but it seems to be quite different from C4-HSL. “We are currently working to purify and identify this molecule". https://blogs.princeton.edu/research/2017/08/21/researchers-find-an-alternative-mode-of-bacterial-quorum-sensing/. Most importantly see these articles. They are phenomenal.
  • asked a question related to Quorum Sensing
Question
1 answer
Are there universal primers for the amplification of LuxI synthase gene homologues? I'm trying to check if my isolates carry a homologous LuxI synthase gene.
Any suggestions? Thanks!
Relevant answer
Answer
This paper discuss the problem in designing the universal primer of LuxI.
  • asked a question related to Quorum Sensing
Question
6 answers
Can we consider quorum-sensing regulation in bacteria as epigenetic regulation in eukaryotic cells ?
Relevant answer
Answer
Hello, Quorum sensing of bacteria is the regulation of gene expression in response to fluctuations in cell-population density. Quorum sensing bacteria produce and release chemical signal molecules called autoinducers that increase in concentration as a function of cell density. The detection of a minimal threshold stimulatory concentration of an autoinducer leads to an alteration in gene expression. But each of cell is individual organism.
Eukaryotic gene expression is more complex than prokaryotic gene expression because the processes of transcription and translation are physically separated. Unlike prokaryotic cells, eukaryotic cells can regulate gene expression at many different levels. Epigenetic changes are inheritable changes in gene expression that do not result from changes in the DNA sequence. Eukaryotic gene expression begins with control of access to the DNA.
  • asked a question related to Quorum Sensing
Question
1 answer
Hello everyone,
As part of a chemical ecology course, students are required to write a hypothetical research plan for any chemical ecological topic. I have chosen the topic of Characterization of Legume-Exuded Quorum Sensing Mimics on Nitrogen-Fixing Bacteria. Part of this research would involve the characterization of these mimics but I lack knowledge in this field. Currently I have selected liquid-liquid extraction followed by lC-MS, is this a reasonable choice?
Relevant answer
Answer
Dear Hanna Simpson,
Yes, LC-MS is the most effective method as chemical analysis in your possibly study.
  • asked a question related to Quorum Sensing
Question
9 answers
Hi colleagues. I have a technical question. In nowadays I'm working with Quorum sensing inhibition. I had results showing two zones around of paper disk: one growth inhibition zone (close to disk) and another without violacein expression but with bacterial growth. My doubt is if that inhibition of violacein expression is caused by bacterial low density or by real inhibition of Acyl homoserine lactones. Please I need some orientation about it. Thanks !!!
Relevant answer
Answer
I am in consensus with Anthony Ayodeji Adegoke. However, in my experience studies with CV is not enough to conform quorum sensing inhibitory property. In our lab we have identified compounds with significant anti-QS property who exhibited no reduction in violacein production and vice versa.
  • asked a question related to Quorum Sensing
Question
4 answers
What is the simplest, quickest, and/or cheapest way of finding out whether a molecule is involved in a novel quorum sensing / cell-cell signaling / signal transduction pathway?
Most literature explains assays that build on systems that have already been established, involving AHLs, AI-2, DKPs, DSFs, HAQs, etc., but our suspected signal molecule is not similar to those. It might be involved in cessation of cell growth, and we sort of have growth curves at different concentrations of the compound.
Outside of forward and reverse genetics, which would be especially difficult for our organism, an Archaeal methanogen, I’ve seen the most plausible options in this paper:
Affinity chromatography and photo-affinity labeling don’t seem simple or quick or cheap, though.
I’d appreciate any suggestions.
Relevant answer
Answer
Dear Elisa,
It is always difficult to go from growth experiments to the identification of an active compound, especially if your model organism is hard and slow to grow, you lack a fast and simple assay for the activity, and if you are not based in a biochemical lab. However, there are some simple experiments that you can do to narrow down the nature of your active compound.
I would suggest that you try some simple growth addition experiments to demonstrate that the effect is real, and that cells are responding to this compound in a dosage-dependent manner. The easiest experiment is to add some filter-sterilised (FS) culture supernatant from cultures in which you see cell death or growth-inhibition to a fresh culture - you would expect to be able to inhibit the growth of this or see cell death occurring earlier than if you did not add FS culture supernatant.
If this works, then there are some simple tests you can do : test FS culture supernatants from cultures grown in different media, grown for different lengths of time, and grown to different cell densities. Try fractionating your FS culture supernatant using dialysis membrane or filters (with different pore sizes) to see if you can put a size limit on the active compound; try heat inactivating the compound, and precipitating or extracting it with alcohol, phenol, ammonium sulphate, etc.
The aim of all of this is to produce a semi-purified concentrated extract that you could then consider fractionating by HPLC and then identifying the compound by mass spectroscopy (if you had access tho this type of analytical equipment). Being able to demonstrate that you have a semi-purified extract plus a simple phenotype you can assay activity with would be a good end-point for a project where you could not do any further biochemical analyses.
Regards, Andrew.
  • asked a question related to Quorum Sensing
Question
7 answers
May I know the different types of signaling molecules in bacteria and fungi. Do different bacteria have different signaling molecules. Which are intracellular and intercellular molecules
Relevant answer
Answer
In addition to AHL, AI-2, and DSF , the following database lists DKPs (Diketopiperazines) and HAQs (4-hydroxy-2-alkylquinolines)(, and "others") as categories of signaling molecules. You can search the database by organism, too.
  • asked a question related to Quorum Sensing
Question
7 answers
I was doing N-Acyl homoserine lactone (AHL) extraction from bacteria using 0.1% acidfied ethyl acetate. Wondering does certain bacteria tolerance to this so that I might leave bacteria broth and acidfied ethyl acetate mixtures for extended time so that better yield of AHLs?
Relevant answer
Answer
I also find layer of bubbles as stated by Uma. Can anyone please tell if it is fine to spool out that layer before subjecting the entire solvent extract for drying in a rotary evaporator?
  • asked a question related to Quorum Sensing
Question
6 answers
Hello!
As a bachelor student, on my faculty we are allowed to run short student-led research projects. I decided to take on one such, and it will be concerned with quorum sensing in Gram-negative bacteria.
I have acquired a few biosensor strains that together ensure a rather good range of coverage of AHLs produced by the potential species studied. My only problem is, I can not decide on this species!
Ideally, I would like to characterize some species that is medically, agriculturally or ecologically relevant. But each and every bacterial species I have gone though has been already studied for their AHL composition.
Be it as it may, I am only a bachelor student and I might not have the bigger picture, nor the right search approach.
Considering all of the above, I decided to seek help in directing me to an interesting species. Alternatively, maybe there is another angle I fail to see under which I could utilize AHL-detecting biosensors in a scietifically relevant way? Maybe something easily doable with quorum quenching and biofilms? I only have three weeks of effective time, sadly.
Any input is appreciated!
Thanks
Relevant answer
Answer
Dear Zaduryan
Please, find in the attached file a review article titled "Messing with Bacterial Quorum Sensing".
I think and hope it's benefit for you. Regard
  • asked a question related to Quorum Sensing
Question
4 answers
from
Theoretically, the Quorum Sensing (QS) mechanism may be disrupted by any condition which prevents a faithful "count" of SC neighbors. This can be either due to reduced sensitivity of the SC itself, e.g., shortage of adequate receptors for environmental signals, or due to reduced "clarity" in the environment, concealing extracellular signals from the SC. The result in both cases is weakened ability to sense the "true" number of SCs in the micro-environment and, as a consequence, incessant proliferation and elusion of normal homeostatic tissue control. These two properties can be integrated into one parameter, the magnitude of intercellular communication sensed by a SC, which is expected to be the critical determinant of the tissue's steady-state production of end cells.
Agur Z, Kogan Y, Levi L, et al. Disruption of a Quorum Sensing mechanism triggers tumorigenesis: a simple discrete model corroborated by experiments in mammary cancer stem cells. Biology Direct. 2010;5:20. doi:10.1186/1745-6150-5-20.
Relevant answer
Answer
Even, ıt is not an answer. please look my reference
  • asked a question related to Quorum Sensing
Question
4 answers
Hello!
we're performing a quorum sensing secretome characterization of a couple of bacterial strains, and we have met a few issues, which we cannot explain.
First, we had our Agrobacterium tumefaciens turn blue in an x-gal plate in absence of any AHLs added or an AHL-producer strain. We can be quite sure that there is no contamination as A. tumefaciens is grown in three antibiotics. The strain that we are using for detection, KYC55, has no HSL production machinery as the wildtype plasmid bearing traI HSL-synthase has been removed in this strain. So no mutations could have led to acquiring (back) production of AHL. So why do we see breakdown of X-gal in the apparent absence of AHLs? Are we missing something?
Second question is about the overlay assay. We got 18C TLC plates silica on glass, and when we poured the LB mixture with the sensor strain on the TLC with AHL bacterial extracts, the silica layer deattached from glass and started floating. We will only see tomorrow morning if this affected the assay anyhow, but we were wondering if this deattachment could be somehow avoided.
Thanks!
Artur
Relevant answer
Answer
Dear Artur Zaduryan,
Kindly purify the A. tumefaciens again by simple streak plate method, pickup single colony, grow overnight in LB with antibiotics and try the biosensor assay once again.
I have sent the TLC procedure in detail by personal email.
Hope this will help.
Best wishes,
HARSHAD
  • asked a question related to Quorum Sensing
Question
2 answers
Hello!
I am preparing to conduct a quorum sensing signal molecule assay on a bacterial species, where I would like to characterize the secretome of n-acyl-homoserine lactones (AHLs) that this species utilize.
I will be using RPC C-18 TLC assay. For this, I will have to synthesize AHL standards, which I will apply on the TLC next to the supernatant extract to be able to evaluate on the composition of AHL in the sample.
Since I will be synthesizing a bunch of these compounds C4-HSL, C6-HSL, C8-HSL, C-10 HSL, C12-GHSL their oxo-derivatives and other) and the starting materials are not so cheap, I was wondering, what is the minimal amount of those to successfully use on a TLC? Should be pretty small I assume?
Thanks!
Artur
Relevant answer
Answer
It's better if you use the conc. within 0.5 to 1 μg/ml.
  • asked a question related to Quorum Sensing
Question
4 answers
Dear colleagues,
I would like to know how expresses the Quorum sensing communication system in the response to physicochemical stress in lactic acid bacteria notament in Lactobacillus sp (if there are articles concerning this subject, please propose me)
Relevant answer
Answer
Thank you dear professor for your interesting response. If you have articles concerning the subject, please propose me.
  • asked a question related to Quorum Sensing
Question
1 answer
Unfortunately, I wasn't able to find the answer to my question in the literature.
Relevant answer
Answer
Hi Rok,
The answer is 'yes' and 'no': take a look at the review of Pereira et al. (2013) https://academic.oup.com/femsre/article/37/2/156/623107/AI-2-mediated-signalling-in-bacteria.
Authors claim that "although the signal synthase, corresponding biosynthetic pathway and chemical products are the same in every AI-2-producing bacterium tested thus far, these studies demonstrate that the molecule ultimately detected by these bacteria can differ". There are a few intermediates and their derivatives which apparently also bind to receptors, thus opening the possiblity that other (closely related) molecules could serve as signals. There might be some update on this in the more recent literature, but this is not really my narrow field, so I hope you will get more hints on this.
Best regards,
Marko
  • asked a question related to Quorum Sensing
Question
7 answers
I am planning to design a simulation for quorum sensing system and biofilm formation in S. Aureus. In order to do so, I would be needing kinetic data or affinity constant data for various protein-protein, protein-DNA or protein-substrate interactions. Naturally, I could try obtaining data for all individual proteins experimentally by myself, but if the data have been obtained already, I would rather not go through all that trouble. So if anyone knows about any database or repository which contains such data, I would be immensely grateful. Thank you! :)
Relevant answer
Answer
The enzyme database BRENDA (http://www.brenda-enzymes.info) would have that type of info if it is available at all.
  • asked a question related to Quorum Sensing
Question
3 answers
efflux pump and quorum sensing  system
Relevant answer
Answer
PubMed: "efflux"[title/abstract] and "quorum sensing"[title/abstract] 
  • asked a question related to Quorum Sensing
Question
10 answers
Does anybody could tell me general PRIMERS for the detection of AHL (quorum sensing) in bacteria please? It is being a big difficult to find them, Thank you!
Relevant answer
Answer
Since your question is still open, you may want to add some details on the specific AHLs (HSLs) you are interested. The HSL classes involve quite a number these days and only the P. aeruginosa system is well characterized. I would not rule out your request for “primers” and I am again guessing you meant routine PCR, as valid. Indeed PCR may be used for HSL determination but one would usually employ qPCR be more definitive. For example in the P. aeruginosa if you run a qPCR for LasI and LasR (using a baseline gene off course), you will derive a highly sensitive information of the quantitative expression of the HSL, N-3-oxo dodecanoyl-L-homoserinelactone. The primers and PCR conditions are available online, but we will be happy to help.
Therefore, PCR may very well be used for studying QS expression but restricted to specific related genes. However if one would need a truly unbiased, global approach for HSL detection (please note nearly all HSL reporter strains and sensitive to specific classes and not ALL HSLs), one would choose LCMS (Cataldi et al. 2008) or LDI-MS (Ghosh et al. 2012) . If you have either of these technologies available, you can detect nano-molar levels of a-n-y HSL of choice, irrespective of their classes or bacteria . Hope this helps!
Suggested reference:
1. Cataldi, T. R., et al. (2008). "Profiling of N‐acyl‐homoserine lactones by liquid chromatography coupled with electrospray ionization and a hybrid quadrupole linear ion‐trap and Fourier‐transform ion‐cyclotron‐resonance mass spectrometry (LC‐ESI‐LTQ‐FTICR‐MS)." Journal of mass spectrometry 43(1): 82-96.
2. Ghosh, D., et al. (2012). Selective Detection and Analysis of Small Molecules, Google Patents. EP2676287B1
  • asked a question related to Quorum Sensing
Question
7 answers
Cultures of Pseudomonas aeruginosa have a distinctive smell due to the production of 2-aminoacetophenone. Dose Pseudomonas aeruginosa produce 2-aminoacetophenone  as virulence factor or act only diagnostic criteria?
Relevant answer
Answer
Thank you Dr. Aamal.
  • asked a question related to Quorum Sensing
Question
2 answers
in my knowledge, there are three identified external death factor for bacteria, is it true?
those have a limited range action, is there a broad range of them?
Relevant answer
Answer
I discuss about other things. EDF is a quorum sensing signals that starting programmed cell death in bacteria and it isn't extra cell toxin. EDF in some way caused unstable toxin-antitoxin complex in bacterial cell.   
  • asked a question related to Quorum Sensing
Question
3 answers
Working concentration of AHL in minimal media is 2.5 mM and in water is 5 microM.
Relevant answer
Answer
Dear Shamas,
I do not know the reason you need so much concentration but I agree with Uelinton about the range of nM to microM is enought to activate the phenotypes depending on QS molecules. 
As an example you can see the natural range of AHL production by the pathogen bacteria Edwarsiella tarda.
  • asked a question related to Quorum Sensing
Question
4 answers
I am interested in quantifying quorum sensing in microbial biofilms. Is there any simple procedure to do so without using reporter bacteria
Relevant answer
Answer
You can use HPLC methodology to detect and quantify AHLs quorum sensing molecules in your samples.
  • asked a question related to Quorum Sensing
Question
3 answers
If anyone has the full text of this paper please do attach it as a file or send it as a  mail (monipj.95@gmail.com).
Nonomura, H. (1974). Key for classification and identification of 458 species of the Streptomyces included in ISP. J Ferment Technol 52, 78–92.
Relevant answer
Answer
Unfortunately, (Nonomura, H. (1974), is not available on the net. However, for identification of Streptomyces spp. , Shirling and D. Gottlieb, (attached below), would be so helpful, and for identification of other actinomycetes, the following attached article may be helpful: 
  • asked a question related to Quorum Sensing
Question
5 answers
I have a bacteriocin with known mechanism of antibacterial action (known receptor), can I check in silico for susceptible bacterial strains to this bacteriocin?
If yes, how would you propose to do this (in proteome, genome, which tools)? I would be even interested in longer and more formal cooperation. Maybe, you know any publications with in silico predictions of resistance/sensivity to antibacterial agents in different bacteria?
Any help would be appreciated,
Thanks
Relevant answer
Answer
Hi Ewelina,
Firstly you have to identify the homologs of known receptor present in all the susceptible strains. You can address this by identify the known receptor in all strains using protein-BLAST using non-reduntant database.
If these protein sequences are present in other strains having simiarity higher than 40%. Then there is strong possibility that the bacteriocin will act against other strains as well.
To further confirm the possibility of interaction of bacteriocin with other strain proteins, you have to perform Multiple sequence alignment (MSA) of known receptor in all strains. If the binding site residues of bacteriocin which may possible interact with your known receptor (through X-RAY, NMR or docking studies) you can look for similar residues in other homologs. If they are conserved (indicated by Astrix or dot sign in MSA), then most possibly the inhibition will occur in other strains.
  • asked a question related to Quorum Sensing
Question
4 answers
Is it possible that A. tumefaciens A136 encounter some type of Mutation after serial culturing? if not then why it's not giving positive result even for positive control in Quorum sensing investigation?
Relevant answer
Answer
@Sergey Dobretsov, Sir I am using Marin Agar on which both A136 and my test strains grows well but not responding to X-Gal even to positive control. sir my protocols are as follow
1. Culturing of Reporter strains using Marine Agar.
2. Culturing of Positive and test strains > incubating them for 24/48 hours > culturing them with repoter strain A136 in T manner> incubatin them for 24/48 Hours at 28 °C > adding X-Gal > Cheking for QS activity after 12 hours then after 24 hours then after 36 hours then after 48 hours.
Sir is there any thing wrong in this protocol? if yes kindly guied me.
Respectful Regards,
  • asked a question related to Quorum Sensing
Question
3 answers
please provide details of vendor or researchers from whom I can procure the toxins
Relevant answer
Answer
Thank you very much Pendru Raghunath and Gamal Enan for the kind information.
  • asked a question related to Quorum Sensing
Question
3 answers
I found the growth curves of S. aureus are different when some specific medicines was respectively added into the defined medium. Some have longer exponential phase, while others showed the shorter. Does anyone know about this? Is related to the Quorum Sensing System? 
Thanks!
Relevant answer
Answer
Is this associated with the phenomena of  SCV? 
My opinion is that it is part of Population diversity/heterogeneity you should look for Phenotypic Switching and Small Colony Variants in those showing different exponential phases.  Generation of microbial heterogeneity in response to stress. Also did you consider the age  of the parent inocula? 
  • asked a question related to Quorum Sensing
Question
5 answers
How do you combine 3 or more compounds to increase the bioactivity e.g. synergy?
Relevant answer
Answer
Synergy is possible when the desired biological activity or pharmacological activity has several sites of action or targets.If the used compounds act on different targets , similar activity can b observed
  • asked a question related to Quorum Sensing
Question
1 answer
The initial data in my lab suggest that Compound X has an inhibitory role on the growth of E. coli in LB media, therefore, E. coli has developed a new class of transporters to translocate this compound to the outside of cytoplasm. Given that there is no previous data on the biological process that might be responsible for Compound X production, I am looking for possible methods to find out what substrate/process might produce it and what is the putative target of this compound in the cell. 
Currently, I am using M9 media and replace the N-source with similar chemicals to Compound X. I am hoping that I will find a chemical that does not affect WT growth but inhibits the growth of the corresponding transporter deletion mutant. 
Do you have any other suggestions how to further investigate this ides?
Relevant answer
Answer
Have you checked the KEGG Compound database? 
There you can search for a compound and then select it to see their associated reactions and pathways. 
I hope that helps.
  • asked a question related to Quorum Sensing
Question
4 answers
Does the AHL molecule in quorum sensing system could trigger the cell multiplication directly ? or the AHL molecule just act as signal within the bacteria population which not directly trigger the cell multiplication but just activated the virulence gene when reach the treshold?
Relevant answer
Answer
The vast majority of gram negative Quorum sensing systems that have been studied thus far utilize N- AHLs as signaling molecules. When in high enough concentrations, these molecules can bind to and activate a transcriptional activator, or R protein, which in turn induces expression of target genes. The use of biosensors to screen spent culture supernatants has led to the discovery that AHLs are produced by a plethora of unrelated bacteria. Biosensors typically consist of a QSC promoter fused to a reporter such as lac Z or the lux operon
In gram positives, Quorum sensing systems typically make use of small post-translationally processed peptide signal molecules. These peptide signals interact with the sensor element of a histidine kinase two-component signal transduction system
  • asked a question related to Quorum Sensing
Question
2 answers
Hi everyone
I work at a project contain detecting AHLs from an activated sludge process (lab-scale) but despite all efforts I could not see any color on the TLC plates. My protocol is including:
1- Extract AHLs by ethylacetat. centrifuge the sample (10 ml), remove the supernatant, add 5 ml ethylacetat, vortex for 2 hours, centrifuge and take supernatant as AHLs solution, and then dried at 60 centigrade.
2- Add 100 microliters methanol and spot 3-5 microliters on TLC plate (Silica gel RP-18 Merck) and then develop in a glass tank with methanol/water (65:35), and then dried at room temperature.
3- The dried plates were overlaid with a culture of the indicator bacterium prepared as follows. For 20 × 20 cm plates, a 5-ml overnight culture of NT1(pDCI41E33) was used to inoculate 50 ml of LB and the new culture was grown 3-4 hours. The entire 55 ml of culture was added to 100 ml of the same medium containing 1 g of melted agar and 60 μg/ml 5-bromo-4-chloro-3-indolyl β-d-galactopyranoside (X-Gal) maintained. The culture was mixed thoroughly and immediately spread over the surface of the developed plate held in a Plexiglas jig designed to produce a uniform layer of agar about 3 mm thick. After the agar solidified, the coated plates were incubated at 28°C for 24 hr in a closed plastic container.
These were the method for detecting quorum sensing signals in detail in our laboratory.
I don't know what is the problem!!
Relevant answer
Answer
Methods have been developed for determination of the AHLs using TLC  Separations were usually performed on fused silica capillary columns 20 m long with hexane as mobile phase and with temperature gradients from 100 to 300 °C. Sometimes, however, sensitivity was lower than expected. There could be several reasons for this, for example masking effects by matrix constituents, e.g. diketopiperazines, the polar nature of the AHLs.
  • asked a question related to Quorum Sensing
Question
2 answers
Efflux Transporters used for certain compounds and efflux that compound from the cell to the media. But I am working on Triterpenoids, and their is no know Transporters to efflux that compound from the cell to the media. So I want to know is their any strategy if we can design the new transport protein that may work to Efflux the C30H50O from the Cell to the Media. 
Or 
If we can predict that yes this specific transporter may Efflux the target compounds from the cell, because there are thousands of transport protein so we cant check all for just one compound as it is time consuming.
So if you dear can tell me some strategy .....
Thanks in Advance.
Regards
Relevant answer
Answer
@Adam B Shapiro: Dear the Compound is Beta-amyrin and is produced in some plants. But their is no known Transporter responsible to efflux it from the Cell. 
Some other Suggestion please because we already check the related Transporter but no reported todate.
Regards
  • asked a question related to Quorum Sensing
Question
8 answers
on the Effects of Antibiotics on Quorum Sensing in Pseudomonas aeruginosa paper by skindersoe et. al, they have used skimmed milk.
i am searching for a test for protease and elastase. im going to use a plant extract of tannins, is it possible that i use that method to?
how can that test (skim milk test)  prove the effectivity of my sample? or how what is the manifestation of a postive result for this test?
Relevant answer
Answer
I agree with all answers above ...good luck.
  • asked a question related to Quorum Sensing
Question
2 answers
Does  anyone know where to get chromobacterium violacelium Cv026 for our  quorum sensing research?
Relevant answer
Answer
 Thank you so much.
  • asked a question related to Quorum Sensing
Question
3 answers
Did you ever research about a bacterium that has appearently almost never been studied in detail? Like for example Pseudomonas Mendocina S178S (JF513150). There is no trace of it in the literature!
What would you do if you wanted to know about its habitat, growth conditions, pathogenesis and competitive behaviour? Would you relate to literature about the whole species or do you think that would be inaccurate?
Thank you a lot!!
Relevant answer
Answer
 Dear Alice,
You have made your microbe very very specific with the strain number 'S178S (JF513150)'. I googled the name of the microbe Pseudomonas mendocina and found some literature (old as well as current) on it. Since the species (mendocina) of the genus (Pseudomonas) is studied and reported in those literature you can have some clear idea on growth conditions if you compare the conditions used in different literature. In my opinion you can easily check it is working with your specific strain or not. For habitat and pathogenesis, exceptions and variations will always be there though. The competitive behaviour can only be assessed if it is grown with another microbe with similar nutrient requirement. I am listing the links of the literature I found for you, but think you will find more of them if you search further (in Sciencedirect, Google Scholar etc.).
4. J Clin Case Rep 5:598. doi:10.4172/2165-7920.1000598
5. doi: 10.1097/IPC.0000000000000394
Hope these will be helpful to you.
Regards,
Shiladitya
  • asked a question related to Quorum Sensing
Question
4 answers
I was trying to make the aqueous stock solution of AHL (3-oxo c12 HSL). I dissolved 3-OXO- C12 HSL (20mg/ml) in ethyl acetate containing 0.01% glacial acetic acid and it was evaporated by passing Nitrogen gas. I got a white precipitate in the bottom of the tube which was insoluble when tried  to dissolve in aqueous  buffer.
Please suggest what else I can change in the protocol for making the aqueous stock.
Relevant answer
Answer
Hello Vivek.
My partner worked with the same AHL, and instead of glacial acetic acid, we used 0,05% formic acid with ethyl acetate to prepare our stocks of all AHLs that we use. We had the same situation (white precipitation). Once we prepare the stocks, we put at -20°C, then before of dissolving with the broth, we just resuspend  in a vortex. We didn't notice a precipitation in our test, probably because the volume we used was minimal. Still it would be great to know if there is a properly way to dissolve this particular AHL since it is hydrophobic.
I found this, hope it helps...
We find that AHLs are best maintained as stock solutions in
ethyl acetate acidified with glacial acetic acid (1 ml of acetic
acid per 1 L of ethyl acetate). We store them at −20°C in glass
vials. If borosilicate vials are used for this purpose, prior to
adding AHL solutions, glass vials are first treated with 0.2 N
HCl, and then rinsed extensively with deionized water.
Teflon-lined caps should be used for capping vials containing
organic solutions of AHLs. As needed for experiments, serial
dilution of 3-oxo-C12-HSL can be prepared in other organic
solvents (including ethanol, methanol and acetonitrile), however
stability of the compound in these solutions is not known.
3-oxo-C12-HSL is not stable in aqueous solutions where it
converts into tetramic acid, an antibiotic (22). At neutral or
basic pH, AHLs undergo spontaneous lactonolysis (23).
From Chapter 9 "Luminescent Reporters and Their Applications for the Characterization of Signals and Signal-Mimics that Alter LasR-Mediated Quorum Sensing" - Quorum Sensing: Methods and Protocols
Best regards.
  • asked a question related to Quorum Sensing
Question
14 answers
We have tested a compound for its antibacterial activity. here we found 75% inhibition of growth but no MIC was found. Can anyone help me with answering this query?
Relevant answer
Answer
In my opinion that much high amount of compound to determine MIC is not worth for drug discovery related process. Because there are limitation to achieve these concentrations inside the invivo systems. Nowadays people are looking for nanomolar activities with biologicaly safe molecules, So I suggest you to look for active molecule having fractional MIC in micrograms. 
  • asked a question related to Quorum Sensing
Question
7 answers
Hi all,
I worked with P. aeruginosa PAO1 for quite a number of years already. First, in my lab at the California State Polytechnic University, I used an ATCC strain. Now I use a strain that Dr. Barbara Iglewski sent to a colleague.
In both cases, the strain produced a lot of mucus. Have you found mucoid variants of this strain? I know that hydrogen peroxide can induce a mucoid conversion of the strain but, do they convert spontaneoulsy to mucoid variants? I can attach pics if you would like to see them.
Thanks
Relevant answer
Answer
Already established that pseudomonas nearly always mutates into a mucoid strain. The alginate-containing matrix of the mucoid strain is thought to allow the formation of protected microcolonies and provide increased resistance to opsonization, phagocytosis, and destruction by antibiotics. Its mutation which increase the adaptation capability of strain. It can be virulent pulmonary pathogen causing cystic fibrosis, be careful !
  • asked a question related to Quorum Sensing
Question
2 answers
Quorum Sensing Inhibition, Membrane bioreactors, anti-fouling
Relevant answer
Answer
 Bacteria are social organisms capable of interacting with
each other and their surroundings. Particularly well
described is the ability to coordinate gene expression in
accordance with population density, a process termed
quorum sensing (QS) (Fuqua et al., 1994)
Read 1. Quorum sensing inhibitors: a bargain of effects article review,
2. Advances in Applied Microbiology, Volume 33
  • asked a question related to Quorum Sensing
Question
4 answers
i am planning to work on providing a better biological solution for membrane fouling in membrane bio reactors. will introduction of genetically engineered organisms into MBR would be of any help? besides quorum quenching?
Thanks in advance.!
Regards,
gopi.
Relevant answer
Hi Dear
pls. see attached manuscript that may help you 
  • asked a question related to Quorum Sensing
Question
4 answers
I am working on quorum quenching enzyme assay. My AHL stock is prepared in DMSO. In CV026 bioassay, my enzyme shows quorum quenching activity. For kinetic study, we are performing OPA based assay for detection of HSL. The read out of the OPA assay is very less. As the substrate concentration increases,the DMSO % goes upto 6-7 % in the final reaction mixture of the enzyme and the AHL (in DMSO). Is there any other way to prepare a stock solution with less DMSO without solubility issue ? Any advice on improving the OPA assay is requested. 
Relevant answer
Answer
I just found your posting by chance today. Although your question is quite long ago, I would like to answer it as no one did this before. You might simply prepare stocks with much higher AHL concentrations. What is your currently used concentration? In my paper I wrote: "Stock solutions of C6-HSL and C8-HSL (400 mM) were prepared in anhydrous dimethyl sulfoxide (DMSO) containing 0.2% glacial acetic acid and stored in aliquots at -20°C." Even when I used 2 mM AHL for biocatalysis, the DMSO concentration was negligible. For long-chain AHLs you might have to use lower stock concentrations. The activity assay I published might be an alternative to the OPA method if it is not working properly. Good luck for your research!
  • asked a question related to Quorum Sensing
Question
1 answer
S. aureus produces many carotenoids, how can one differentiate staphyloxanthin from other carotenoids? Is production of all these carotenoids under control of quorum sensing in this bacterium?
Relevant answer
Answer
Extract the carotenoids, analyse by TLC; or HPLC using RP C18 column. Best...
  • asked a question related to Quorum Sensing
Question
1 answer
Hello
I am planning to establish the quorum sensing inhibition assay and i need tester strain wither c. violeceum or V. harvei. Is anyone can share the culture with me free of cost?
Relevant answer
Answer
Dear Ahmed
I have CV026 and NT1 biosensors, but according the regulation of post in Iran it is impossible to post the bacteria. do you have any suggestion for it?!
  • asked a question related to Quorum Sensing
Question
6 answers
A joined work project in quorum sensing inhibition
Relevant answer
Answer
I want to make joined work. I can make some of the work in my lab. and you can complete the experiments I can not make due to lack of equipments for example or some standard strains and we can publish together. 
  • asked a question related to Quorum Sensing
Question
2 answers
According to Quorum sensing controlled virulence factors , What is the regulatory mechanism of gelatinase enzyme in pseudomonas aeruginosa .
Relevant answer
Answer
Hi there,
Gelatinase which participates degradation of collagen is involved in the ECM degradation process in order to generate peptides to be uptaken by the bacteria for  supplying substrates for cell metabolism. It is one of the essential activities for bacterial survival during infection.
  • asked a question related to Quorum Sensing
Question
6 answers
I am involved in an ongoing study looking at biofilm infection in patients. To my knowledge QSI are not yet used but may be advantageous in the fight against chronic bacterial infection. Any advice in this area gratefully received.
Relevant answer
Answer
Dear Cat,
With regard to biofilm infection I have a paper which might be of interest for you. See attachment.
Kind regards
Stig Jeansson
Attached: Bacteria, biofilm and honey_a study of the effects of honey on 'planktonic' and biofilm-embedded chronic wound bacteria 
I
  • asked a question related to Quorum Sensing
Question
1 answer
For screening of quorum sensing inhbitiors
Relevant answer
Answer
For $185, you can purchase from ATCC (kind of a steep price, if you wanted my opinion on the matter): 
An alternative suggestion is to find a source of C. violaceum that is not an ATCC strain. Academic groups often will distribute these freely.
  • asked a question related to Quorum Sensing
Question
5 answers
I am working on Quorum sensing activity.
Is there any possibilities that in Pseudomonas aeruginosa, pyocyanin activity decrease as crude plant extract concentration increases?
Relevant answer
Answer
Pyocyanin, one of the many virulent factors produced by Pseudomonas aeruginosa, is a zwitter ion whose activity in in vitro studies suggest it interferes with multiple cellular functions. But few cellular pathways affected by pyocyanin activity are known. However, high concentrations of pyocyanin have been deemed crucial for most related infections. So it's possible that the crude plant extract with increasing concentration interfered with QS interactions, as a result lowering the virulent factor (pyocyanin).   
  • asked a question related to Quorum Sensing
Question
5 answers
Rf values of TLC method for AHLs detection is mentioned in many paper, could we use them to Identify AHLs in our work?! (in the same condition)
Relevant answer
Answer
The ideal situation would be to run on same plate at same time.  It is possible for different lots and plates in same lot to have slight differences that may affect Rf values.  If you have confidence in standard and the match is valid, then it should be okay .  I am a forensic scientist so I have a bit more sensitivity to slight variations than a research chemist, but you should still show that the match is valid each time you open a new box of plates.  An easy way to do this is once you have a pure substance as discussed above such as shown by GC, LC, MS, etc, save a portion of that material as secondary standard to use with TLC.  It will also show if degradations  occur under your conditions.
  • asked a question related to Quorum Sensing
Question
7 answers
When I was reading about quorum sensing mechanism, it seems to be that they are bacteriostatic. But, their are reports which are saying that QS agents can act as an antibacterial.
Can anybody suggest me the answer?
Relevant answer
Answer
The term antibacterial can apply to both bacteriocidal or bacteriostatic agents. So the reports that say the QS agents are antibacterial may have just not defined whether they are bacteriostatic or bacteriocidal.
Some QS inhibitors are bacteriocidal at higher concentrations, while quorum sensing inhibitory at lower concentrations. Given the nature of quorum sensing, I would also have thought that QS inhibitors (when acting as inhibitors, not bacteriocides) would be bacteriostatic. However, if the process that is regulated by QS is essential to the survival of the bacteria, then inhibition of this process would lead to mortality. However, this would mean that the bacteria would not be able to survive in sparse populations, which seems like something that would be selected out pretty quickly. Unless of course this was an inter species interaction that enhances competitiveness of one species (the QS inhibitor producer) over another (the species that needs the QS process for survival).
  • asked a question related to Quorum Sensing
Question
1 answer
#essential oils #quorum sensing #quorum quennchig #microbiology #need for new protocol # recently published paper on similar idea
Relevant answer
Answer
Hi
Most of essential oils have photodynamic activity, with a simply assay diffusion disc, exposing the plate to different lights you'll find interesting differences.
best regards
  • asked a question related to Quorum Sensing
Question
8 answers
Examples such as those found in ants, bees, bacteria etc. point to the fact that collective decision making is also an important aspect of decentralized decision-making process. Most bacteria utilize quorum sensing to maintain population density, ants use it to find new nests, and recently, robots and self-organizing systems are using this signalling mechanism for decision-making. This forms the basis of Swarm intelligence. Incorporating some of these signalling aspects of SI into AI systems would make them more efficient and 'intelligent', do you agree?
Relevant answer
Answer
Dear @Sidartha, I find this article is very relevant for your issue.
How 'artificial swarm intelligence' uses people to make better predictions than experts?
"Dr. Louis Rosenberg, CEO of Unanimous AI, is building a software platform, UNU, that assembles groups to make collective decisions. "What's different about this is that it fundamentally keeps people in there," he said. "We're focused on using software to amplify human intelligence."...
UNU is an online platform where anyone can log in and answer questions as a swarm. "People benefit when they form a real-time system the way bees, fish, and birds do, as opposed to people just casting a single vote the way people do," said Rosenberg..."
  • asked a question related to Quorum Sensing
Question
12 answers
I am trying to make a working concentration of 500 uM 3oC12HSL in LB (or any other aqueous medium for bacterial growth) by diluting my stock solution of 100 mM 3oC12HSL in DMF. Every time I add my stock solution to the medium the AHL starts to precipitate. I understand it is sparingly soluble in water. Is there any way to dissolve AHL into aqueous medium?
Relevant answer
Answer
The good thing about ethyl acetate is that you can add it to your test tube and wait for it to evaporate, leaving only the AHL behind. However, the same principle applies when storing your working solution. Ethyl acetate will evaporate even in freezer at -18C. So, after a while, the concentration of AHL will change.
That does not happen when using acetonitrile. So, say you stock it in acetonitrile, at high concentration, you can then dissolve it in sterile distilled water (or your growth medium) at a more suitable concentration before using it in your media. 
However care must be taken in order to avoid growth inhibition due to acetonitrile. So, when adding it to your media, make sure it is only a tiny fraction (10 to 100 microL of AI in acetonitrile to 100 mL of media).
  • asked a question related to Quorum Sensing
Question
4 answers
hi im currently conducting  a research on inhibition of quorum sensing of pseudomonas aeruginosa, and one of its virulence is the proteolytic and elastolytic activity, how can i show the inhibition of these two using my sample which is a plant extract?
Relevant answer
Answer
You may consider using a zymography analysis with the introduction of specific substrates (gelatin, for example) into gel. Use conditioned media that contains secreted products for the analysis. This will allow you to identify conditions (quorum sensing, inducing factors) that promote the expression of proteolytic phenotype in P. aeruginosa. The sequence analysis of the eluted protein will help you to identify the protease that is inhibited by the plant extract. Specifically to elastase, you can use its capacity to degrade collagen. Using commercially available fluorescein-labeled collagens, you can perform high throughput screening analysis in 96 well plates (see Shogan et al., STM 2015, Collagen degradation and MMP9 activation by Enterococcus faecalis contribute to intestinal anastomotic leak) for the analysis of your plant extracts
  • asked a question related to Quorum Sensing