Questions About Quorum Sensing?

[KUMAR5]

Hello all,
Greetings!!

In other topics, I came to know about Quorum Sensing whose inhibition appear to be an active
and dynamic subject with anticipated promising outcome to deal with problematic issue of Antibiotic
Resistance with modern science. Following are few snips about it:-

In biology, quorum sensing (or quorum signalling)[1] is the ability to detect and respond to cell population density by gene regulation. As one example, quorum sensing (QS) enables bacteria to restrict the expression of specific genes to the high cell densities at which the resulting phenotypes will be most beneficial. Many species of bacteria use quorum sensing to coordinate gene expression according to the density of their local population. In a similar fashion, some social insects use quorum sensing to determine where to nest. Quorum sensing may also be useful for cancer cell communications...
Bacteria[edit]
Some of the best-known examples of quorum sensing come from studies of bacteria. Bacteria use quorum sensing to regulate certain phenotype expressions, which in turn, coordinate their behaviours. Some common phenotypes include biofilm formation, virulence factor expression, and motility. Certain bacteria are able to use quorum sensing to regulate bioluminescence, nitrogen fixation and sporulation.[6]

The quorum-sensing function is based on the local density of the bacterial population in the immediate environment.[7] It can occur within a single bacterial species, as well as between diverse species. ..
Viruses[edit]
A mechanism involving arbitrium has recently been described in bacteriophages infecting several Bacillus species.[39][40] The viruses communicate with each other to ascertain their own density compared to potential hosts. They use this information to decide whether to enter a lytic or lysogenic life-cycle...
Quorum quenching[edit]
Quorum quenching is the process of preventing quorum sensing by disrupting signalling.[50] This is achieved by inactivating signalling enzymes, by introducing molecules that mimic signalling molecules and block their receptors, by degrading signalling molecules themselves, or by a modification of the quorum sensing signals due to an enzyme activity.
https://en.wikipedia.org/wiki/Quoru...ensing (or,phenotypes will be most beneficial.

Now my questions are:-

1. Can Quorum quenching or Quorum sensing inhibition by its inhibitors will just deal with the virulence and pathogenicity of Bacteria etc. or will also decrease their growth, population and evolution?

2. If it can not decrease their growth, population and evolution than, how such quorum quenching will evolve or change such bacteria etc. subjected to quorum sensing inhibitions? Will they start behaving individually and independently instead in some quorum? In other sense, will they become somewhat anti-social from social...may be somewhat like cancer cells?

Best wishes.

 

[KUMAR5]

. "The increasing occurrence of multiresistant pathogenic bacterial strains has gradually rendered traditional antimicrobial treatment ineffective. Today, a global concern has emerged that we are entering a post-antibiotic era with a reduced capability to combat microbes, and, hence, the development of novel therapeutic approaches to the treatment of bacterial infections constitutes a focal point of modern research. The alternative to antibiotic-mediated bacteria killing or growth inhibition is attenuation of bacterial virulence such that the organism fails to establish successful infection and, in consequence, is cleared by the host immune response. "

Above indicates Antiquorim sensings may just be related to virulence of pathogens not to their survival and growth directky....so also to their evolution. So how they can evolve to resist quorum quenching, is a big question.

 

[Write4U]

. "The increasing occurrence of multiresistant pathogenic bacterial strains has gradually rendered traditional antimicrobial treatment ineffective. Today, a global concern has emerged that we are entering a post-antibiotic era with a reduced capability to combat microbes, and, hence, the development of novel therapeutic approaches to the treatment of bacterial infections constitutes a focal point of modern research. The alternative to antibiotic-mediated bacteria killing or growth inhibition is attenuation of bacterial virulence such that the organism fails to establish successful infection and, in consequence, is cleared by the host immune response. "

Above indicates Antiquorim sensings may just be related to virulence of pathogens not to their survival and growth directky....so also to their evolution. So how they can evolve to resist quorum quenching, is a big question.

This lecture by Bonnie Bassler at Princeton U. will explain a lot of the fundamentals involved in quorum sensing and how it could help in combating bacterial infection and assist in beneficial bacterial behavior.
This is a longer version of her TedTalk and goes into greater detail on how the process works.

and

 

[KUMAR5]

This lecture by Bonnie Bassler at Princeton U. will explain a lot of the fundamentals involved in quorum sensing and how it could help in combating bacterial infection and assist in beneficial bacterial behavior.
This is a longer version of her TedTalk and goes into greater detail on how the process works.

Welcome here and thanks for the vedios. I shall look these bit later. However, do you feel that quorum quenching or quorom sensing inhibition can reduce offending microorganisms survival, population and growth or will only deal with their virulence?

 

[Write4U]

Welcome here and thanks for the vedios. I shall look these bit later. However, do you feel that quorum quenching or quorom sensing inhibition can reduce offending microorganisms survival, population and growth or will only deal with their virulence?

Good question. I don't know. I would guess that antibodies would clean then up eventually.

Perhaps the same principle could stimulate bacteriophages and assist in killing the invaders.

 

[KUMAR5]

Good question. I don't know. I would guess that antibodies would clean then up eventually.

Perhaps the same principle could stimulate bacteriophages and assist in killing the invaders.

This can be indirect killing. In my 2nd post, it is mentioned:-
". The alternative to antibiotic-mediated bacteria killing or growth inhibition is attenuation of bacterial virulence such that the organism fails to establish successful infection and, in consequence, is cleared by the host immune response. "

Above can suggest that quorum quenching tecnique will take care only virulence but when there will be no virulence host immune response will clear those organisms....so an indirect control. However I feel such process may evolve those organasms in long run to byepass it and become anti social individuals from social in a quorum. If it will happen it may be more horrible.

 

[Write4U]

However I feel such process may evolve those organasms in long run to bypass it and become anti social individuals from social in a quorum. If it will happen it may be more horrible.

No, if the individuals are unable to communicate at all, they will not become virulent by themselves, they will be deaf and dumb to each other and unable to evolve. Even if an individual would learn to become virulent by itself, it would not be of any effect. We are much too big for an individual bacteria to harm us. Hence their need for amassing large numbers before they turn ON their virulence. All the viruses have a special key-hormone that only fits their "receptors". The method of rendering them unable to communicate is to imitate their auto-inducing hormone, but with a false "key-word", which plugs up their key-hole and prevents the auto-inducer to trigger virulence.

As Bassler observed the Cholera bacteria work in reverse. They are a gut bacterium and are virulent when in small numbers, and can make you very sick from diarrhea and dehydration, but if you survive that initial attack and the bacteria become numerous, their quorum sensing causes them to turn OFF their virulence, detach from their hold and get flushed down the toilet. A remarkable reverse of their survival mechanism. It can be devastating but to a healthy individual it need not be fatal, IOW the virus leaves and allows the host to recover.

The trick there is to find out what inducer hormone causes then to turn OFF and introduce that early on to tell the bacteria to stop virulence and leave the host. That of course also solves the problem of cleaning the body from the cholera bacteria.

But as we learn to communicate with all bacteria we may be able to induce all of them to remain dormant and/or just leave the host by some method. The beauty is that we are dealing with pure chemistry and there is no choice involved by the bacteria. They must obey their chemical coding and if we can scramble the code or introduce a false auto inducer to stop them from multiplying, they remain non-virulent and unable to procreate.

 

[KUMAR5]

No, if the individuals are unable to communicate at all, they will not become virulent by themselves, they will be deaf and dumb to each other and unable to evolve. Even if an individual would learn to become virulent by itself, it would not be of any effect. We are much too big for an individual bacteria to harm us. Hence their need for amassing large numbers before they turn ON their virulence. All the viruses have a special key-hormone that only fits their "receptors". The method of rendering them unable to communicate is to imitate their auto-inducing hormone, but with a false "key-word", which plugs up their key-hole and prevents the auto-inducer to trigger virulence.

As Bassler observed the Cholera bacteria work in reverse. They are a gut bacterium and are virulent when in small numbers, and can make you very sick from diarrhea and dehydration, but if you survive that initial attack and the bacteria become numerous, their quorum sensing causes them to turn OFF their virulence, detach from their hold and get flushed down the toilet. A remarkable reverse of their survival mechanism. It can be devastating but to a healthy individual it need not be fatal, IOW the virus leaves and allows the host to recover.

The trick there is to find out what inducer hormone causes then to turn OFF and introduce that early on to tell the bacteria to stop virulence and leave the host. That of course also solves the problem of cleaning the body from the cholera bacteria.

But as we learn to communicate with all bacteria we may be able to induce all of them to remain dormant and/or just leave the host by some method. The beauty is that we are dealing with pure chemistry and there is no choice involved by the bacteria. They must obey their chemical coding and if we can scramble the code or introduce a false auto inducer to stop them from multiplying, they remain non-virulent and unable to procreate.

I noted one point from your above post that some bacteria also behave in reverse manner. That they are more virulent when in small numbers eg Cholers bacteria. Then why these can't be taken as evolved bactetia which became anti social from social? May be due to some natural anti quorum sensing inhibitors. I am trying to look this possibility in case of other social bactetias subjected to anti social treatments.

 

[Write4U]

I noted one point from your above post that some bacteria also behave in reverse manner. That they are more virulent when in small numbers eg Cholers bacteria. Then why these can't be taken as evolved bactetia which became anti social from social? May be due to some natural anti quorum sensing inhibitors. I am trying to look this possibility in case of other social bactetias subjected to anti social treatments.

I think it may have something to do with the environment the cholera bacteria occupy, the gut, which is rife with a host of different bacteria. There may be as many as 400 different (benign) bacteria, and may offer a safe environment for early virulence without the presence of many bacteriophages.

This is pure speculation, but it seems reasonable to assume that a different, perhaps more hospitable environment may determine the point where a reversed quorum sensing mechanism is beneficial to the bacteria. They would be more like raiders, rather than occupiers.

 

[Write4U]

2. If it can not decrease their growth, population and evolution than, how such quorum quenching will evolve or change such bacteria etc

Bassler believes that controlling quorum sensing but not killing the bacteria,
prevents the evolution of resistant strains.

Ran across this article that may be of interest.

Gut Bacteria in Health and Disease
Eamonn M. M. Quigley, MD, FRCP, FACP, FACG, FRCPI

Abstract

A new era in medical science has dawned with the realization of the critical role of the “forgotten organ,” the gut micro-biota, in health and disease. Central to this beneficial interaction between the microbiota and host is the manner in which bacteria and most likely other microorganisms contained within the gut communicate with the host’s immune system and participate in a variety of metabolic processes of mutual benefit to the host and the microbe.

The advent of high-throughput methodologies and the elaboration of sophisticated analytic systems have facilitated the detailed description of the composition of the microbial constituents of the human gut, as never before, and are now enabling comparisons to be made between health and various disease states.

Although the latter approach is still in its infancy, some important insights have already been gained about how the microbiota might influence a number of disease processes both within and distant from the gut. These discoveries also lay the groundwork for the development of therapeutic strategies that might modify the microbiota (eg, through the use of probiot-ics).

Although this area holds much promise, more high-quality trials of probiotics, prebiotics, and other microbiota-modifying approaches in digestive disorders are needed, as well as laboratory investigations of their mechanisms of action.

http://sciforums.com/threads/questions-about-quorum-sensing.164343/#post-3675491

 

[KUMAR5]

Bassler believes that controlling quorum sensing but not killing the bacteria,
prevents the evolution of resistant strains.

Ran across this article that may be of interest.

Gut Bacteria in Health and Disease
Eamonn M. M. Quigley, MD, FRCP, FACP, FACG, FRCPI

Abstract
http://sciforums.com/threads/questions-about-quorum-sensing.164343/#post-3675491

Yes, for the time being it will help but I can not say what can happen in long term. Controlling quorum sensing is also
a mean to harm bacteria. Nature has gifted every live being(not only to human) to survive and grow normally or by evolution. We can not think, we can extinct these bacteria in absolute. So they will opt best to survive and grow in changed environment. GUT is very much and directly exposed to many odd and even substances. So why microorganisms present in gut can not be taken as evolved for those exposures of various odd and even substances and became anti-social? It may be happening in case of all forms of lives.

 

[Write4U]

Yes, for the time being it will help but I can not say what can happen in long term. Controlling quorum sensing is also a mean to harm bacteria. Nature has gifted every live being(not only to human) to survive and grow normally or by evolution. We can not think, we can extinct these bacteria in absolute.

I don't think it works quite that way.
When we kill bacteria it is impossible to kill them all, but we will kill all the weaker strains and a few more resistant strains will survive and multiply . In effect, when we kill viruses we are playing with "artificial selection", just like nature does with natural selection. The end result is that only the most resistant specimen survive to procreate . This is not the case with altering their communication mechanisms which leaves all individuals alive but impotent of virulence.

Consider that bacteria have hormonal keys (words), which fit only their own species' receptor locks (ears). Now we artificially introduce keys that will fit the locks but are missing the auto-inducers. Now the keywords (containing the auto-inducers) produced by the bacteria are unable to fit in the lock because it is occupied by the fake key. At this point we can kill the bacteria or stimulate the bacteriophages, and even if some resistant bacteria survive, they will be unable to communicate and eventually the body will cleanse itself . The point of preventing quorum sensing is not to control the virus but its ability to become virulent.

We literally confound their language.....

But I do like your thought processes and if this subject is of interest to you and you are young enough, I can see a promising career in bacteriology, and that would most likely keep you busy for the rest of your life.

 

[KUMAR5]

I don't think it works quite that way.
When we kill bacteria it is impossible to kill them all, but we will kill all the weaker strains and a few more resistant strains will survive and multiply . In effect, when we kill viruses we are playing with "artificial selection", just like nature does with natural selection. The end result is that only the most resistant specimen survive to procreate . This is not the case with altering their communication mechanisms which leaves all individuals alive but impotent of virulence.

Consider that bacteria have hormonal keys (words), which fit only their own species' receptor locks (ears). Now we artificially introduce keys that will fit the locks but are missing the auto-inducers. Now the keywords (containing the auto-inducers) produced by the bacteria are unable to fit in the lock because it is occupied by the fake key. At this point we can kill the bacteria or stimulate the bacteriophages, and even if some resistant bacteria survive, they will be unable to communicate and eventually the body will cleanse itself . The point of preventing quorum sensing is not to control the virus but its ability to become virulent.

We literally confound their language.....

But I do like your thought processes and if this subject is of interest to you and you are young enough, I can see a promising career in bacteriology, and that would most likely keep you busy for the rest of your life.

Thanks for comments.
Let us pray, it hapoens as you told i.e. bacteria does not get evolved to such quorum quenchings. However,Bacterial evolution refers to the heritable genetic changes that a bacterium accumulates during its life time, which can arise from adaptations in response to environmental changes or the immune response of the host. Because of their short generation times and large population sizes, bacteria can evolve rapidly. As such Bactetial antibiotic resistsnce is also one kind of acquiring evolution. It suggests, bacteria does get evolved to changed environment in their benefit. Furthur, looking at other side of quorum sensing, it may also be possible that microorganisms feel more secure when together in large numbers, lead them to be less virulent but in small numbars they may feel more insecure so more virulent. I think, it is true in case of gut cholera bacteria (as you indicated earlier). So it is always productive to try to look all sides of any new concept.