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Slime can be great, but when it's the wrong kind of slime (you know, the kind that can kill you?), it gets added to the list of things Hank wishes he didn't have to worry about. Scientists call it biofilm, and it's a type of bacterial colony the produces a sticky organic glue which anchors the organisms to each other and to whatever surface they fancy.

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Hello, I'm Hank Green, welcome to SciShow, where we love slime. Slime is great, except when it's the wrong kind of slime, and when I say the wrong kind, I mean the kind that can kill you.


(0:15) Biofilm, also sometimes referred to as slime, is a type of bacterial colony that produces a sticky organic glue which anchors the microorganisms to whatever service they fancy, and also to each other, making them exponentially better/worse than they would otherwise be. It's also the latest addition to my list of things I wish I didn't have to worry about.

(0:34) We tend to think of bacteria as free-wheeling loners making their way through the world all by themselves, and sometimes they are that way. Those are called planktonic bacteria. But scientist are beginning to realize that bacteria actually spend most of their lives as biofilm, which makes them way, way, way better at doing what they do. Whether it's helping us digest food or killing us with cholera. Just as living in towns and cities makes us more effective as a species, bacteria living together as biofilm allows them to divvy out labor, protect each other and share food, and that frees up more time and resources to do the stuff like digesting and the killing.

(1:12) Their secret is the slimy goo that many bacteria secrete, made up mostly of complex sugar called polysaccharides along with some proteins to form a sort of infrastructure of these bacterial towns. This concoction of chemicals is actually very similar to a substance our own bodies create, and that you may be familiar with, mucus.

(1:32) Through this slime, different bacteria can share nutrients and water, they can also send signaling proteins to let them communicate, they can even swap DNA to pass along their genes, it's like the united freaking nation of germs up in there. 
Because this structure makes micro-organism successful, scientist estimate that 60-80% of bacteria that causes human infection actually live as biofilm. And because the only thing they need to start a colony is water, they pretty much form in every environment on earth, from super hot hot spring to the inside of your mouth. In fact, if you rub your tongue along your teeth right now, you can probably feel, maybe even taste the most wildly known form of biofilm, plaque, which is actually a biofilm that contains up to 500 different species of bacteria and is the number one cause of periodontal disease.

(2:17) Other biofilms are responsible for even gnarlier infections like cystic fibrosis, legionnaires disease, and all kinds of chronic ear, sinus and skin infections. To make matters worse, their thick, slimy matrix often makes biofilms antibiotic resistant. One study found that bacteria and biofilm were 1000 times more resistant to antibiotics than the same bacteria were when they were on their own. But the real insidious part is that biofilms periodically shed their individual bacteria which then go off and start their own infections, while antibiotics can kill these planktonic bacteria often making everything seem cool for a while, the biofilm death star is just hanging out there waiting to release more of it's little TIE fighters to attack the body again. 

(3:00) As a result, biofilm infected tissue sometimes has to be removed surgically, their that tenacious. I know it's gross and also, it's scary. So what are scientist doing to protect me, and also you, but more importantly me, from biofilms?

(3:14) Well for now, scientist are finding out more about them and how they work, so they can develop drugs that can break down the slime in order to help the antibiotics work at the bacteria within the film. 

(3:22) And what are we doing here at SciShow? Well just know that we made a conscious decision to not show you any actual images or footage of biofilms in the human body. So be thankful for that and have a good day.

(3:35) And if you want to keep getting smarter with us, here at SciShow, you can go to and subscribe.