in this video, we're going to begin our lesson on ph requirements for microbial growth and so similar to temperature, microbes grow in a range of pH values. However, inside of this range of ph values is what's known as the optimal ph value, and the optimal ph value is the specific ph at which the species grows most rapidly, or the ph that allows the microorganism to grow the best. Now, despite the ph of the surrounding environment, cells tend to maintain an internal ph near neutral. And so microbes that live in acidic environments have mechanisms that pump protons out of the cell to help contribute to that acidic environment. And on the other hand, microbes that live in alkaline or basic environments have mechanisms that pump protons into the cell to help contribute to the basic environment. And so if we take a look at our image down below notice, on the left hand side, we're focusing in on an acidic environment and the aesthetic environment is going to have more protons, That is what makes it acidic. And so notice that the inside of the cell, regardless of if it is in an aesthetic environment or a basic environment, the inside of cells tends to be neutral. And so we have a neutral ph in the inside of the cell. But notice that cells that live in acidic environments tend to pump protons out of the cell. And so notice that the protons here are being pumped towards the outside pump towards the outside pump towards the outside. And that helps contribute to the higher concentration of hydrogen ions and the environment leading to an acidic environment. Now, over here, on the right hand side, we're focusing in on a micro growing and a basic environment. And so of course, the environment that is basically is going to have less protons in the environment. And so the inside of the cell, once again, regardless of the ph of the environment, is gonna tend to have a neutral ph, So there's a neutral ph over here and a neutral ph over here, because the inside of cells tends to always have a neutral ph. However, the microbes that live in basic environments, they tend to have mechanisms that pump protons into the cell, and so notice that the protons are being pumped into the self, and that helps to contribute to the basic environment because it reduces the amount of hydrogen ions and the environment. And so that leads to a basic environment. And so this here concludes our brief introduction to ph requirements for microbial growth. And as we move forward in our lesson, we'll be able to learn even more about these ph requirements. And so I'll see you all in our next video.

in this video, we're going to begin our lesson on the optimal growth ph classes of microbes. And so microbes are actually classified into three groups based on their optimum ph ranges. And so down below, we're showing you an image of the growth ph classes of microbes. And so notice in this graph on the Y axis, we're showing you the cell growth rate. And so the higher the Y axis value is the higher the cell growth rate and the better the cells grow. And then on the X axis. What we're showing you is the ph scale which has the values that range from 0 to 14. And then notice that we have these three different curves on this graph, the red one, this green one here and then this blue one over here and these three different curves correspond with the three ph classes of microbes. And so the first one that we have here, this red one is going to correspond with the Asado files and the Asado files are going to have ph values optimal ph values that are less than or equal to 5.5. And so notice that here is the ph value of 5.5. And the Asado files are going to all have optimum ph values less than uh 5.5. And so here in this curve, what you can see is that the the actual optimal ph value is going to be a value of about 3.5, which is very acidic. And so that's why they're referred to as a cinephiles. And so these organisms have the highest growth rate in uh ph and environments that have ph values that are acidic. Then what we have are the neutral files here in green. And notice that their optimum ph values range between 5.5 and 7.9 from here to about here. And so their optimal ph values are going to be very near neutral. That's why they're called neutral files. And they have the optimal growth rate at a neutral ish ph Then the third and final group that we have here is going to be referring to the alcohol of files. And the alcohol files are of course referring to organisms that grow in basic or alkali environments. And so notice that they have optimum ph values that are going to be greater than, or equal to eight. And so notice that here this curve shows the highest cell growth rate at a ph value right around 10. And so uh that is showing you a basic ph value that allows for the best growth for these Alcala files. And so what you can see are some examples of different environments to have. These specific ph is like volcanic soil. Ph of one stomach acid is the right around 2.5. Pure water is a neutral ph, right around seven. Seawater is eight, and alkaline soda lakes Are going to have ph values between nine and 12 and so these are really the three ph classes of microbes, and we'll be able to get some practice applying these concepts as we move forward in our course. So I'll see you all in our next video.