In this video, we're going to begin our lesson on pH requirements for microbial growth. Similar to temperature, microbes grow in a range of pH values. However, within this range of pH values is what's known as the optimal pH value. 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. Microbes that live in acidic environments have mechanisms that pump protons out of the cell to help contribute to that acidic environment. 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.
If we take a look at our image down below, notice on the left-hand side, we're focusing on an acidic environment. The acidic environment is going to have more protons, which is what makes it acidic. Notice that, inside the cell, regardless of whether it is in an acidic or a basic environment, the inside of cells tends to be neutral, so we have a neutral pH inside the cell. But notice that cells living in acidic environments tend to pump protons out of the cell. The protons here are being pumped towards the outside, which helps contribute to the higher concentration of hydrogen ions in the environment leading to an acidic environment.
Now over here on the right-hand side, we're focusing on a microbe growing in a basic environment. The environment that is basic is going to have fewer protons. Once again, regardless of the pH of the environment, the inside of the cell tends 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 tend to have mechanisms that pump protons into the cell. The pumped protons are being pumped into the cell, and that helps to contribute to the basic environment because it reduces the amount of hydrogen ions in the environment, leading to a basic environment.
This here concludes our brief introduction to pH requirements for microbial growth. As we move forward in our lesson, we'll be able to learn even more about these pH requirements. I'll see you all in our next video.