ID#: 15379
These four test tubes illustrate both a positive (+), and three negative (-) decarboxylase reactions used to identify a bacterial microorganism through the identification of its life-sustaining metabolic processes. After each tube had been inoculated with a bacterial culture, mineral oil had been added in order to cover the medium, thereby, preventing atmospheric oxygen from coming into contact with the medium. This provided an anaerobic growth environment devoid of oxygen. Tubes 1, 3, and 4 revealed a negative reaction (yellow-orange), while organisms in tube 2 provided a positive decarboxylation reaction (purple). “Various decarboxylase-based media are used in the biochemical differentiation of Gram-negative enteric bacilli based on the production of arginine dihydrolase, and lysine and ornithine decarboxylase.”
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Content Provider(s): CDC/ R. E. Weaver, MD, PhD
Creation Date: 1971
Photo Credit:
Links: Becton Dickinson and Company (BD) - Difco™ & BBL™ Manual, 2nd Edition; from ”Biochemical tests for identification of medical bacteria, 3rd ed.”, by MacFaddin, 2000, Lippincott Williams & Wilkins, Baltimore, Md.
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Copyright Restrictions: None - This image is in the public domain and thus free of any copyright restrictions.