Fig. 13B: Fermentation of a Carbohydrate:
Acid and Gas End Products
![](images/acid_gas.jpg)
Acid end products from carbohydrate fermentation turn the pH indicator phenol
red from red (alkaline) to yellow (acid). A large gas bubble (arrow) collects
in the Durham tube.
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Microbiology Laboratory Manual by Gary E. Kaiser, PhD, Professor of Microbiology
is licensed under a Creative Commons Attribution 4.0 International License.
Last updated: September, 2017