in this video, we're going to begin our lesson on plating methods. Starting specifically with the streak plate method. And so the streak plate method is actually the most common and the simplest way of isolating microbes in a laboratory. And so by isolating what we really mean is if we have a mixture of a bunch of different types of microbes, we can actually isolate one single type of microbe by performing the streak plate method. And so in the street plate method a mixed culture of cells is going to be transferred to a Petri dish and uh it is then going to be streaked across the plate using what's known as an inoculate er And so an inoculate er can be defined as either a metal or glass loop. That is going to be used to isolate and transfer colonies of bacteria between growth media. And the method of the street plate method is actually outlined in a series of eight steps that we have numbered down below in our image. And so in this image, it's really focusing in on this streak plate method. And so let's say over here on the far left and step number one, we are going to take our inoculate er which is actually this metal loop here and we are going to sterilize our inoculate er or our loop with a direct flame from a Bunsen burner as you can see here. And so this flame is heating up our metal rod to help sterilize it and make sure that there's nothing alive on that metal loop. Once the loop has been sterilized, then once the loop has cooled down, you can take your loop and dip it. You can dip the loop into the culture. And so notice that the glass or the metal loop is being dipped into a culture media and this media is going to contain a bunch of microbes inside of it and it's going to have a mixture of, a bunch of different types of microbes. And so you dip uh the uh inoculate er or this loop into this media and you get some of that uh that those microbes on the tip of the loop. And so in step number three, what you're going to do is you're going to streak the first area of the plate and so notice here we are streaking area number one and basically spreading those microbes in just one specific area on the plate. And so this is gonna be a mixture of a bunch of microbes here. Then in step number four, what we're going to do is we're going to sterilize the loop once again. And so we're gonna take our inoculating loop and we're going to sterilize it by using the Bunsen burner flame. And then after the loop has cooled down, we will streak area number two in the plate. So basically what you do is you pull a little bit of microbes from area number one, and you use that to uh streak area number two. And so area number two will have less microbes Than Area # one. And then in step six, what you do is you sterilize the loop once again, and then in step seven, you streak area number three. And so an area number three over here, basically, you pull a little bit of microbes from Area number two and you spread them over here in area number three. And so area number three is gonna have even less microbes. Then area # two. So, an area number one will have the most amount of microbes. Area number two will have the second most amount of microbes. An area number three will have the least amount of microbes. And so ultimately, what you end up getting over here is your uh street plate, your final street plate and your final streak plate here is going to have area number one, which has the most amount of microbes. Area number two over here, which is going to have the second most amount of microbes. And then Area number three notice has the least amount of microbes. And these microbes are in so little amount that they actually form individual colonies. And these individual colonies can be selected and picked in order to isolate them from the remainder of the group. And so this is really the basics of the street plate method. And it is a common method that is used in many microbiology labs. And so, if you take a microbiology lab, you're very likely to use this street plate method. And so this year concludes our introduction to plating methods and the street plate method specifically. And, as we move forward in our course, will be able to apply these concepts and learn about other plating methods as well. So I'll see you all in our next video.

In this video, we're going to continue to talk about plating methods by talking specifically about the spread plate method and the poor plate method. And so when transferring a liquid culture to a solid auger plate, the liquid cultures can be added to that solid auger plate in one of two methods that we have numbered down below one and two. The first is the spread plate method, Where 01-0 two ml of a diluted liquid culture is going to be added onto the solid auger plate and then it is going to be spread with a sterile glass rod. And so if we take a look at our image down below at the spread plate method, which is the top half of this image here, uh notice that in this first to what we have is a liquid culture that is going to have microbes growing in a liquid broth. And so what we can do is we can take some of this liquid culture and the microbes growing in the liquid bra, and we can take about 0.1-0.2 mm and transfer it over to a a solid auger media. Uh and so we are inoculating the culture onto the auger media. And so this is the inoculation right here. And then what we can do is we can actually spread the inoculation with a glass rod. And so here we have the glass rod. And this glass rod can be used to spread the in Oculus across the entire plate. And if the liquid culture is diluted enough, then eventually what you'll get our colonies growing on the solid auger media. And so ultimately what we've done through this process is we've taken microbes growing in a liquid broth and we've transferred those microbes over to a solid auger plate. And so we've done that through the spread plate method. Now, the other method is actually the Poor plate method And the poor plate method. You can take anywhere between 0.1 and one ml of diluted liquid culture, and you can pour it onto an auger plate before the pre warmed liquid auger is poured onto the plate. And so the warmed liquid auger media that's added afterwards is actually going to solidify. It solidifies, but it only solidifies after it is mixed with the sample, the liquid culture sample. And so if we take a look at our image down below, we can get a better understanding of this poor plate method, which is in this bottom half of the image here and so once again, we're starting with the test tube here that is containing a liquid broth containing microbes that are growing. And so what we can do is we can take anywhere between 0.1 and one millimeter of this liquid broth diluted liquid broth and we can pour it right here onto an empty plate. Notice that this is an empty Petri dish and there is no auger added yet. The notice that the microbes are added first. Um and so that's different than what we see up above and then after the inoculation is added after the uh the culture is added, the liquid culture is at it. Then you can pour the pre warmed media over the in Oculus. And so this is the pre warmed liquid auger media and it is being poured on top of the inoculation that contains the microbes. And then at that point, what you do instead of spreading using a glass rod, what you do is you actually pick up the plate and you swirl it around physically. You swirl the plate around to mix before the august solidifies. And so you mix simply by swirling and over time. Eventually if you have the right appropriate dilution of the original liquid culture, you will get uh colonies growing on a solid plate. And so once again, what we've done is we've taken microbes growing in a liquid broth and we've been able to transfer them onto a solid auger plate. And we've done this through the poor plate method. And so the spread plate method and the poor plate method allow for transferring microbes from liquid broths over two solid auger plates. Now, one thing to note about both of these methods is that unlike the streak plate method that we covered in our previous lesson videos, these two methods, the uh spread plate method and the poor plate method cannot be used to isolate specific species of bacteria from a mixed culture. And so that is a unique feature of the street plate method. And once again, the spread plate and pour plate method are not capable of that of doing that. And so this year concludes our introduction to the spread plate method and the Poor plate method, and we'll be able to get some practice applying these concepts as we move forward. So I'll see you all in our next video.