Fig. 2B: a Durham tube to Detect Gas

Acid end products from carbohydrate fermentation lower the pH causing the pH indicator phenol red to turn from red (alkaline) to yellow (acid). Note gas bubble in Durham tube indicating gas production.

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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