Lecture: Biofilms: Narrator: Listen to part of a lecture in a biology class. Professor: You are now discussing the microorganisms, lets move along to another process – the formation of what we called biofilms. Now biofilms are ... well you may have rocks you find in rivers and lakes be coated with a kind of slippery substance or slimes you might find on the bottom of the boat, for instance, or the plaque that plants on your teeth for that matter. All of those are biofilms and biofilms are really not well-understood until pretty recently. Oh well I said recently, I mean the 1970s, you guys may have different perspectives. Anyway, before then we just assumed that the slippery stuffs was like algae or some other forms of plant life, but it never could anyone but its actually bacteria – the most basic one-celled organism – are responsible for these shielding. A biofilm is basically a colony of bacterial that grows on moist surfaces. And it exhibits characteristics that an individual bacteria on its own does not. Biofilms are pretty much stick with its peer: they can stick virtually on any wet surface you can think of – pipes, sinks, floors. And higher biofilms develop and be broken down into a few basic steps and remember of course that these all takes place at microscopic level the biofilm is no more than a tenth of millimeter thick. So what happens first some bacteria are free-coating, they are sort of hanging out in the lake because that's what one-cell organisms usually do, they float independently in a liquid. Then a few of them attached themselves to some surfaces a rock, a boat, and a wet surface. More bacteria follow and attach themselves to the surface or directly to the first colonist and they begin to reproduce on that surface. So the bacteria colony is growing and spreading on that surface. And then the bacteria undergo changes and they are sending out chemical signals to one another. These signals allow the bacteria to sense when the community is large enough to function collectively. At that point what they do is start secreting a sticky substance called extracellular meant outside their cells – extracellular polysaccharide. Polysaccharide is just sugar compound, so they collectively create a big sugary mass – the biofilms, which is the last phase of the development. The bacteria are covered by that mass and this protective environment allows them to work together in various ways. When there's enough polysaccharide, the bacteria are able to start forming really complicated structure. For example: with the biofilm, they create channels, water channels allows them to both bring nutrients in and remove waste, anything they don't need. Also, if the bacteria are still reproducing and get overcrowded, they can use the channels to move bacteria around to newer part of the biofilm, so the bacteria can move to different places within the biofilm. Now it may happens that they are in thus fantastic protective environment, but they start to run out of room. So they let some bacteria become detached from others in the biofilm and form a little pocket, OK? And then when enough bacteria are in the pocket, it ruptures, and the bacteria become free-floating again. They'll go colonize another rock or another nearby surface all over again. Biofilms provide an evolutionary advantage for bacteria. Alone bacteria is vulnerable. But in biofilm, they are incredibly resistance to just about anything you use to get rid of them. So you can scrub it but they stick to it well. You can try to use disinfectant or antibiotics, but biofilms are pretty resistant to all these methods. That's why biofilm research has exploded these years. So we can get a better understanding of surface-attached bacteria as opposed to free-floating ones. And hopefully we'll find more efficient ways to get rid of biofilms, since they can cause a lot damage, from equipment damages to infections of our body. And I have mentioned plaque before, a biofilm that forms on the surfaces of our teeth can cause toothache if we don't scrub regularly. But there also increase research of biofilm for another reason. And that my surprises, they actually can also help clean up polluted areas as well, can be beneficial too.