Measuring Growth by Membrane Filtration - Video Tutorials & Practice Problems
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concept
Measuring Growth by Membrane Filtration
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Video transcript
in this video, we're going to begin our lesson on measuring microbial growth by membrane filtration. And so membrane filtration is a process that's used to count the number of viable cells or living cells in liquid cultures, with only a few cells. And so a small number of cells are going to be required. Now in this process of membrane filtration, a known volume of liquid culture is going to be passed through a membrane filter. And this membrane filter has really, really small pores in it, even smaller than cells themselves. And so the cells will actually get trapped in the membrane filter, and colonies will actually begin to form after the membrane filter with the trap cells is transferred to an auger plate and incubated and counting the colonies that forms gives the total number of viable cells or living cells in the original liquid culture. And so if we take a look at this image down below, we can get a better understanding of membrane filtration of microbes and so on the left hand side over here, what we're showing you is uh this filter here and this red sheet that you hear is the membrane filter paper which has all of those tiny tiny pores in them that can be used to trap cells. And so what you do is you pour the liquid culture right into the top of this filter here. And the vacuum that's created down below will will filter all of the liquid through. However, the cells remain trapped in the membrane filter. And so you can remove the membrane filter and put it into a Petri dish with solid growth media. And then that will allow for microbial growth to occur. And so what you'll see here are the actual colonies that are forming. And these colonies once again represent colony forming units. And so they represent individual viable cells. And so uh this year concludes our brief lesson on measuring growth by membrane filtration. And so 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.
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Problem
Problem
Microbial cell colonies can be grown on a solid growth medium or within a liquid growth medium. If you wanted to count the number of bacteria cells in a small colony found in a liquid broth, which counting technique would you use?
A
Flow cytometry.
B
Coulter counting.
C
Membrane filtration.
D
Direct microscopic cell counting.
E
None of the above.
3
Problem
Problem
Many forms of technology have been invented to prevent microbiologists from having to count each and every individual bacterial cell they are studying. Which form of technology is able to count the number of cells in a bacterial population using a laser beam?
A
Flow Cytometer.
B
Membrane Filtration.
C
Coulter Counting.
D
Plate Counting.
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