Scientists have discovered something very special: some bacteria can sense the death of others of their own kind – and change their behavior based on this.
Researchers from Carnegie Mellon University have observed the phenomenon in bacteria from the family Vibrioincluding the cholera bacteria Vibrio cholerae is part of. Towards the end of their lives, the bacteria often explode; a process better known as lysis. During this process, the contents of a cell are ‘left on the street’. Scientists have now discovered something new: norspermidine can also be released during this process. VibrioBacteria can then detect this substance because they have special receivers for this purpose that are located on the outside of the cell, called MbaA. The moment a VibrioWhen bacteria receive a signal from this receptor, something very special happens: they protect themselves by clumping together to form a so-called biofilm.
Scientist Jojo Prentice contributed to the research. He says: “Basically, the point is that we have discovered that bacterial populations can adapt their behavior when they observe the death of others. The most interesting aspect of our research is that we can also explain the mechanisms underlying this.” The research has been published in the journal Nature Communications.
Biofilm
The scientists started their research by first V. cholerae to grow in a number of different petri dishes to see how the bacteria behaved without any danger nearby. During this phase, the researchers noticed that the bacterium was doing just fine: the colonies continued to grow steadily until there was no more space left. Then it was time to repeat the same experiment, but in the presence of a threat. For this purpose, the scientists used bacteriophages: small viruses that only infect specific bacteria. The scientists saw a clear difference in behavior in these petri dishes. In summary, the first 3-5 hours mainly consisted of a huge bloodbath for the V. cholerae. Shortly afterwards, they suddenly noticed a remarkable change: the remaining bacteria started developing a biofilm by clumping together. And that approach worked: thanks to the biofilm, they could continue to grow unhindered and ultimately sustain each other.
“Imagine suddenly seeing someone with a fresh injury,” explains researcher Drew Bridges. “In such a scenario, it is likely that you are mentally alert and would like to protect yourself. We also see the same reaction in bacteria. During our research we discovered that some bacteria can sense internal components of other bacteria. The moment they actually realize that danger is coming, they start preparing (by forming a biofilm, ed.).”
Evolution
The results of the study are significant for two reasons. First of all, it is of course very special that scientists have now proven that bacteria are indeed able to detect the death of others of their own kind. Not only that, they can then also adjust their behavior to ensure that the colony as a whole remains safe. Bridges explains: “The mechanism we ultimately discovered is very simple – but also very important. We would therefore like to know which other bacteria are able to repeat the same trick. In addition, we are also very curious whether the MbaA receptors do more than just encourage biofilm formation.”
However, there is also a second reason why the results of the study are very important. This reason mainly has to do with the disease caused by the bacteria Vibrio cholerae can cause: cholera. It is of course very special and unique V. cholerae has the ability to protect itself. However, it is also true that this bacterium is very dangerous for humans and can even be fatal. It is therefore very important for scientists to understand how dangerous bacteria (such as V. cholerae) protect themselves – and how this method of protection is generally evolving. Scientist Prentice concludes: “It would be fantastic if we could learn more about how bacteria generally respond to hazards. It would be particularly interesting to look at the effects of the ability to change lifestyle. Future studies may well prove that this ability is ultimately an important driver of evolution.”
 the death of others of their own kind){kind=link}