Clearly, the ability of bacteria to communicate with each other is limited – their unicellular form restricts them in this endeavour. Bacteria can, however, communicate by giving off signals called quorum sensing molecules. These molecules are constantly released by bacteria to let each other know how many of them are in the immediate vicinity. When they realize that they have enough of their buddies around, their behaviour suddenly changes and the whole group begins acting in a different manner, often manifesting as an infection (note: the best lecture that I have seen on quorum sensing is available for free below from TED, and it’s only 20 minutes long). Only recently, riots quickly engulfed my hometown of Vancouver, and I was struck by how similar the two processes were. It gives me a small measure of satisfaction to write a piece comparing mindless bacteria to the equally mindless degenerates that briefly infected our city on June 15th.
In the past six years I’ve learned a lot about bugs. Microbes comprise 70% of all living organisms in the world. And we have ten times more bacteria than human cells. So why ponder these peculiar facts? In short, how we understand the myriad interactions between humans and microbes decides how we treat – or fail to treat – a range of human diseases.
My first unexpected foray into the pathology of bacterial disease started in 2005, as I became increasingly ill with an odd constellation of symptoms that eluded doctors. Looking back, it seems possible I visited every medical specialty in western medicine! My shortness of breath, fatigue, cardiovascular troubles and neck pains puzzled my PCP, ENTs, orthopedic surgeons, chiropractors, a physiatrist and an interventional radiologist. And that’s not the complete list. I knew I wasn’t crazy as my health spiraled downward into an indescribable hell.
Richard Longland is looking for a way to get word out about biofilm, and to spread that word beyond the scientific community with his coming film, Why am I Still Sick?. After talking to the real brainpower here at Ondine, Richard sat down with me and captured my views on biofilm and infectious disease for his feature length piece on biofilm. Richard was clearly familiar with the joy I take in making complex subjects easier to understand, and asked me how I would describe biofilm in order to make people aware of the danger it poses. It wasn’t something that I had given thought to beforehand, but the obvious answer was that biofilm communities are the organized criminals of cellular biology.
Stages of Biofilm Development - Source: Wikipedia Commons
Bacteria, which are single-celled organisms, generally exist in either a free-floating, unattached (planktonic) state or in an attached state called a biofilm. A planktonic form suggests these single celled organisms float or swim independently of each other in some liquid medium. A biofilm, or attached state, is created with a change of behaviour triggered by many factors, including quorum sensing. A biofilm is a complex community of a number of different microorganisms coexisting together and marked by the excretion of a protective and adhesive matrix. The biofilm is held together and protected by the matrix, called extracellular polymeric substance or exopolysaccharide (EPS), holds the biofilm together, protects the cells within it and facilitates communication among bacteria through biochemical signals. In a biofilm, cells are closely packed together and firmly attached to each other and usually to a solid surface. Read More
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