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How to test pH levels

Postby 7afdebe3c08a42f1a1f486592f7fc613 » Sun Sep 23, 2018 4:51 pm

Hello! My science fair project is about how prebiotics and probiotics affect gut microbiota (basically gut bacteria). To measure the results of this project I was planning to test the pH levels of the bacteria once they were in the Petri dishes. However, I have done some research and have not been able to find out how to do this. I was wondering if anyone could help me with this? Also, if anyone knows of any other way to test these effects please tell them to me? (By the way, I can not test on humans). And another thing, if anyone has any advice on how to improve my project please tell me.

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Re: How to test pH levels

Postby SciB » Thu Sep 27, 2018 8:29 pm


The human microbiome--all the bacteria, fungi and viruses that make up the cloud of life that inhabits what we use to think of as OUR body is a really interesting and hot area of research.

Measuring the pH of an organism is not something you could do easily. You could change the pH of the agar on which you grow the bacteria, but what would that tell you about the microbiome?

The pH of the gut is near neutral--6.7 to 7.4. Changing the pH would certainly affect the types of bacteria that grow their but how would that relate to anything in the human body? The pH is normally regulated pretty accurately in the body although the gut is sort of a unique environment because it is constantly changing with the different kinds of foods eaten.

What bacterium did you plan to experiment with, E coli? That would be appropriate because it is a bacterium that is normally found in the human gut. Maybe you could prepare a variety of agar plates each containing some different kind of food extract and see what effect it has on growth of E coli colonies. You might be able to relate that to the microbiome of people eating a vegetarian vs a meat diet.

Let us know more about what you want to study and we can help you better.


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