I just finished watching a fascinating TED presentation by Bonnie Bassler of Princeton. I recommend you watch On How Bacteria Talk - she is a gifted scientist and presenter.
I will highlight some of the things I learned and then explain why I performed this research.
We like to think about our personal DNA as defining who we are and why we are the way we are. Yet Bonnie tells that we have lots and lots of bacteria inside of us, and they also have DNA. As an aggregate, our personal DNA only accounts for 10 percent of the DNA within the envelope of our skin.
Most probably you have heard of vibrio fishori, a bacteria which has bioluminescent properties. It had puzzled researchers on what caused these bacteria to produce light. Recently scientists have discovered that small groups of vibrio fishori will not emit light, but only large colonies. Obviously they have some way of determining there are other bacteria around them, and scientists discovered they communicate chemically with a unique enzyme molecule.
As an aside, the vibrio fisheri live in symbiosis with the Hawaiian bobtail squid. This little animal lives at the bottom of the sea and only hunts at night. But even at the bottom of the sea, the moonlight can create shadows that endanger the little squid. It has an eyelid-like structure on its bottom that controls the amount of light emitted by the vibrio fisheri, that matches the intensity of the light above it so the squid does not leave a shadow that can be detected by predators. Fascinating.
But back to the bacterial communication. Further study has revealed that all bacteria communicate. They have two receptors - an intra-species receptor and an inter-species receptor. This means that bacteria communicate to like species, as well as to all bacteria. One special or unique enzyme for inter-species and a common enzyme to communicate to all bacteria. The behavior of the vibrio fisheri was a tipoff. The bacteria use the number of received messages to enable quorum sensing.
Ever wonder how bacteria can suddenly burst into a dangerous infection? It is because of quorum sensing. The bacteria lay low until there are sufficient numbers that they launch an attack upon a larger organism, like an animal body. Their behavior is dependent upon what they perceive from quorum sensing. As I mentioned, they alter their behavior depending upon how many other types of bacteria are around. Again, fascinating, isn't it?
Knowledge of how bacteria communicate is enabling new types of antibiotics. If we can keep the bacteria from communicating, we can disable some attacks until the immune system has the opportunity to individually kill the invaders.
This insight has also led to a new finding, Bacterial Communication Could Affect Earth's Climate, Researchers Discover. Other bacteria in the ocean have the ability to communicate on whether they devour sinking organic matter. If they devour it, they increase the carbon that released to the atmosphere because their bodies will float and be consumed by larger organisms. If they decline, then the organic matter sinks to the bottom of the ocean which is a larger carbon sink. They communicate on whether to colonize and devour the carbon, thus altering the Earth's carbon cycle.
Fascinating. What an amazing world we live in!