+M2Ys4U Subscriber¹ Posted August 16, 2010 Subscriber¹ Share Posted August 16, 2010 Research has shown that bacteria - among the simplest life forms on Earth - have a sense of smell.Scientists from Newcastle University in the UK have demonstrated that a bacterium commonly found in soil can sniff and react to ammonia in the air. It was previously thought that this "olfaction" was limited to more complex forms of life known as eukaryotes. The finding, published in Biotechnology Journal, means that bacteria have four of the five senses that humans enjoy. The discovery also has implications in the understanding and control of biofilms - the chemical coatings that bacteria can form on, for example, medical implants. Bacteria have already demonstrated the ability to react to light, in analogy to sight, and to change the genes that they express when confronted with certain materials, in analogy to touch. Sniff test However, there is a distinction between an organism reacting to a chemical that it encounters directly (in analogy to the sense of taste) and a reaction to a chemical that is floating around in the air, says Reindert Nijland, lead author of the study. "The difference is both in the mechanism that does the sensing, as well as in the compounds that are sensed," Dr Nijland, now at University Medical Centre Utrecht in the Netherlands, told BBC News. "The compounds detected by olfactory organs are generally much more volatile than things you can taste like 'sweet' or 'salt', and therefore can provide information about things that can be much further away; you can smell a barbecue from a few blocks away whereas you have to physically touch and eat the steak to be able to actually taste it." Bacteria are known to use their "senses" to detect chemicals that indicate the presence of other bacteria or competitors for food. In some cases, they can produce a slimy material that causes them to stick together in what is known as a biofilm. Such biofilms can cause complications in cases ranging from implants to oil pipelines, but a familiar example is the plaque that forms on teeth. Dr Nijland and Grant Burgess put a number of separate cultures of a bacterium called B. licheniformis in cylinders containing different "growth media" to cause them to multiply. Some were in a rich broth of food that allowed the bacteria to multiply quickly, releasing ammonia gas in the process, while others were in a medium that allowed the growth of biofilms - which can be initiated if the bacteria are in contact with ammonia. They were surprised to find that some of the isolated bacteria cultures began to form biofilms spontaneously, with those physically closest to the "well-fed" bacteria showing the highest biofilm production. The only explanation is that the bacteria sensed the presence of ammonia directly from the air above the cultures. Film rights Dr Nijland explained that the biofilm provides both a barrier and a means of transportation for the bacteria that have "smelled" nearby ammonia. "It's tempting to speculate that [ammonia] provides the bacteria with information of a nearby nutrient source, since ammonia generally is a waste product of bacteria growing on a rich nutrient source," he said. "The bacteria sense this, organise themselves in a biofilm which will prepare them for both competition with other species already feeding on the nutrient source, and enables swarming - migration via the matrix they have secreted to form the biofilm." The surprise find has implications in our understanding of the difference between prokaryotes like bacteria, which have no neatly packaged parts within their cells, and the more advanced eukaryotes that include everything from yeast to humans. "If very simple organisms such as bacteria are capable of this that would imply that this ability evolved much earlier than expected," said Dr Nijland. "Understanding this phenomenon... will help us to develop methods to potentially interfere with this process and potentially develop new ways of preventing biofilm-related bacterial infections." Source: BBC News Link to comment Share on other sites More sharing options...
Crisp Posted August 16, 2010 Share Posted August 16, 2010 Awesome! Can we move it up a notch and try and actullay study something which will help people? Link to comment Share on other sites More sharing options...
monkey13 Posted August 16, 2010 Share Posted August 16, 2010 More shock news. Bacteria react to the chemicals around them! Who'd of thought such a thing! How this becomes smells baffles me. This is like saying that my can of 7-UP just sensed me pulling the ring pull and that's why it released some of its CO2. Link to comment Share on other sites More sharing options...
+M2Ys4U Subscriber¹ Posted August 16, 2010 Author Subscriber¹ Share Posted August 16, 2010 Awesome! Can we move it up a notch and try and actullay study something which will help people? "There is a single light of science, and to brighten it anywhere is to brighten it everywhere" - Isaac Asimov Link to comment Share on other sites More sharing options...
monkey13 Posted August 16, 2010 Share Posted August 16, 2010 Awesome! Can we move it up a notch and try and actullay study something which will help people? Well if we could find a way to stop biofilms it would make brushing teeth much easier and have loads of industrial applications. My only complaint with this is the likening of this reaction to smell. Which I know scientists only do to get their research onto BBC news or in the papers. Link to comment Share on other sites More sharing options...
zhangm Supervisor Posted August 16, 2010 Supervisor Share Posted August 16, 2010 Ok, there is no information in the article about this, but what controls were done to ensure that the bacteria were sensing the ammonia directly? It is also plausible that the ammonia dissolved into the culture media and raised the pH, causing a change in gene expression leading to biofilm formation. In such a case, we cannot say that the ammonia is acting directly, nor can we attribute the change to a sense of smell. Link to comment Share on other sites More sharing options...
Gilly Posted August 16, 2010 Share Posted August 16, 2010 Ok, there is no information in the article about this, but what controls were done to ensure that the bacteria were sensing the ammonia directly? It is also plausible that the ammonia dissolved into the culture media and raised the pH, causing a change in gene expression leading to biofilm formation. In such a case, we cannot say that the ammonia is acting directly, nor can we attribute the change to a sense of smell. I had similar thoughts. I can't find the paper anywhere, but since in the article they do say "The only explanation is that the bacteria sensed the presence of ammonia directly from the air above the cultures.", I would think they have some controls in place. I don't know anything about B. licheniformis, but presumably they picked a species that exhibits a relatively telltale response in the presence of ammonia as opposed to just a simple pH shift. Link to comment Share on other sites More sharing options...
+M2Ys4U Subscriber¹ Posted August 16, 2010 Author Subscriber¹ Share Posted August 16, 2010 Ok, there is no information in the article about this, but what controls were done to ensure that the bacteria were sensing the ammonia directly? It is also plausible that the ammonia dissolved into the culture media and raised the pH, causing a change in gene expression leading to biofilm formation. In such a case, we cannot say that the ammonia is acting directly, nor can we attribute the change to a sense of smell. Well considering this was published in the Biotechnology Journal, I assume it was peer-reviewed. Link to comment Share on other sites More sharing options...
monkey13 Posted August 16, 2010 Share Posted August 16, 2010 Well considering this was published in the Biotechnology Journal, I assume it was peer-reviewed. It will be but that Journal is new (since 2006) and only has an unofficial impact factor of 2.1. So publishing in that is no great feat. Link to comment Share on other sites More sharing options...
guru Posted August 16, 2010 Share Posted August 16, 2010 is it only Ammonia or anything else too like say methane... Link to comment Share on other sites More sharing options...
ATGC Posted August 16, 2010 Share Posted August 16, 2010 http://en.wikipedia.org/wiki/Quorum_sensing Link to comment Share on other sites More sharing options...
zhangm Supervisor Posted August 16, 2010 Supervisor Share Posted August 16, 2010 Well considering this was published in the Biotechnology Journal, I assume it was peer-reviewed. Now that I'm at work, I may have access to that journal. Going to look for the source now... Edit: I can't find any article in Biotechnology Journal with both Nijland and Burgess as authors. Something to keep in mind is that not all peer reviewers are equal in their rigor. I think that for the authors to support the statements in this news article, they need to show that ammonia molecules are either binding to a receptor on the outside of the cell, or are entering the cell and altering the phenotype by initiating a signal cascade, or by directly binding a transcription factor and inducing a change in gene expression. I suppose that since ammonia is a small molecule, it should have no trouble penetrating the cell membrane without any receptors to assist it. I'm not sure how you really say that this would be "smell". Does lactose entering an E. coli and suppressing the Lac repressor, thus triggering expression of the lac operon also count as smelling? Link to comment Share on other sites More sharing options...
ATGC Posted August 16, 2010 Share Posted August 16, 2010 Put the biology book down. I think they're mistaking quorum sensing for smelling, especially considering they are talking about biofilms. Link to comment Share on other sites More sharing options...
Hum Posted August 16, 2010 Share Posted August 16, 2010 Kinky :yes: Link to comment Share on other sites More sharing options...
zhangm Supervisor Posted August 16, 2010 Supervisor Share Posted August 16, 2010 Put the biology book down. I think they're mistaking quorum sensing for smelling, especially considering they are talking about biofilms. That's part of the picture, but what the news article suggests is that the researchers are proposing that quorum sensing may be effected by "smell". It isn't the response that this article focuses on, they're trying to say something about the mechanism behind it. Link to comment Share on other sites More sharing options...
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