ID#: 15372
Caption:
These four test tubes illustrate both negative (-), and positive (+) decarboxylase reactions, used to identify bacterial microorganisms through the identification of their 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 newly inoculated medium. This provided an anaerobic growth environment devoid of oxygen. Tubes 1 and 3, revealed a positive decarboxylation reaction (purple-orange), while organisms in tubes 2 and 4, provided a negative decarboxylation reaction (yellow). “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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