 Hey everybody, Dr. O here. This video I want to go over the capsule. So I mentioned it in an introductory video earlier, but the capsule is very important so it's worth noting a few examples and also its relationship to something very important, the biofilm. So, the capsule is an example of a glycocalyx, which basically means sticky sugar coat. So microorganisms are able to produce these substances inside of them, these gelatinous like sticky polymer substances that are usually a combination of carbs or proteins or can be both, but they're wildly different amongst organisms. But they have this material that they can spew out onto themselves and coat themselves with. So if it's real loosely laying on there and unorganized it's called a slime layer, but we generally care about the neatly organized capsules. So a capsule is an example of a glycocalyx. Reason that's important is I think of the capsule as kind of a biofilm for a single organism because biofilms are wildly important. According to the CDC at least 70% of the infections that humans deal with are from biofilm forming organisms. So we'll do a separate video about biofilms, but biofilms are really the same thing, but the substance that gets spewed out, but it covers groups of organisms instead of a single one. So think of a capsule as a biofilm for one. So why are they so important? Why is it so important to this organism that has this, it's green in this picture, but it has this capsule, this neatly organized sugary or sticky coat around its surface? Well, it increases virulence and it's believed that the main reason or really the only reason this is the case is that it helps these organisms evade phagocytosis. So think about how many of your immune cells function by phagocytosis. You've got any of your macrophages and neutrophils, you name it. We have macrophages, microphages. So these are all eaters, right? They engulf and destroy things like bacteria. Well, the capsule appears to make that either impossible or way less likely. So I'll give you a couple of examples here. Bacillus anthracis, the causative agent of anthrax. If it has a capsule, it can cause anthrax. If it doesn't have a capsule, it doesn't. And they believe that's because the capsule helps it evade phagocytosis. Streptococcus pneumonia, it is known that from Frederick Griffith's experiments, which we covered in a separate video. If Streptococcus pneumonia bacteria doesn't have a capsule, it cannot cause pneumonia, it cannot, it is not a pathogen. If it has a capsule, it can cause pneumonia, sepsis, meningitis. It still kills 1.4 to 1.5 million humans a year. So the capsule is what makes Streptococcus pneumonia dangerous. Same thing with Clive cellanemonia, another very potent pathogen if it has a capsule, but if it doesn't have one, it's not. So the capsule just think this, this coating on the surface of an organism that makes it virulent or more virulent, which means more dangerous, more pathogenic, because it helps these organisms evade phagocytosis. And then also just keeping the back of your mind for later, that a capsule is pretty much a biofilm for one. So the same sticky coating that goes on one cell can cover communities of organisms as well. And we'll cover that a lot later. All right, I really hope that helps. Have a wonderful day. Be blessed.