Fig. 2B: Fermentation of a Carbohydrate: Acid and Gas End Products

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
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Last updated: September, 2017