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Learn the toughest concepts covered in Microbiology with step-by-step video tutorials and practice problems by world-class tutors.

10. Dynamics of Microbial Growth

Complex Media


Complex Media

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in this video, we're going to begin our lesson on complex media. And so for culturing a large mixture of many different types of microbes, the exact composition of the media does not need to be known. And so this is what we refer to as complex media. And so complex media is going to be a specific type of microbial growth media that contains a variety of nutrients, making it really, really complex. And these nutrients are in the form of cell extracts, for example, yeast, meat and plant extracts. And so these extracts do not necessarily contain a known composition of nutrients. Now the proteins from these cell extracts are going to be partially digested into short amino acid chains that are called pep tones. And so pep tones can be defined as small soluble protein fragments that can be digested by most bacteria. And so if we take a look at this image down below, we can get a better understanding of complex media and so notice that on the far left, what we have are a bunch of meat uh and this meat can be used to get cell extracts basically by grinding the meat and digesting and breaking open all those cells and digesting the proteins. And uh that can lead to the formation of these pep tones. And the pep tones are going to be these protein fragments that you see here, and the protein fragments are going to be used to generate this complex media. And so the complex media is going to have a lot of different types of molecules. However, the exact composition of this complex media is not known. And so that is really what distinguishes the complex media here from the chemically defined media that we covered in our previous lesson videos. And so this allows for a lot of different types of microbes to be able to grow on this complex media because it has so many different types of nutrients uh that can allow for many different types of microbes to grow. And so this year concludes our brief introduction to complex media and how it has nutrients from cell extracts that the composition is not exactly known. And we'll be able to get some practice applying these concepts and learn more about different types of media as we move forward in our course. So I'll see you all in our next video.