A positive Voges-Proskauer reaction is characteristic of which organism?

A positive Voges-Proskauer reaction is characteristic of which organism?

• A. Enterobacter aerogenes
• B. Escherichia coli
• C. Proteus vulgaris
• D. Providencia rettgeri

Answer: (A)

Voges-Proskauer detects acetoin produced during glucose fermentation through the 2,3-butanediol pathway. A positive result appears as a red color after adding the specific reagents, indicating acetoin is present. Enterobacter aerogenes commonly uses the 2,3-butanediol pathway and thus yields acetoin, giving a positive VP test. Escherichia coli typically ferments to mixed acids with little acetoin, so VP is negative. Proteus vulgaris and Providencia rettgeri also do not form acetoin, so they are VP negative. Therefore, the positive VP reaction is characteristic of Enterobacter aerogenes.

Voges-Proskauer detects acetoin produced during glucose fermentation through the 2,3-butanediol pathway. A positive result appears as a red color after adding the specific reagents, indicating acetoin is present. Enterobacter aerogenes commonly uses the 2,3-butanediol pathway and thus yields acetoin, giving a positive VP test. Escherichia coli typically ferments to mixed acids with little acetoin, so VP is negative. Proteus vulgaris and Providencia rettgeri also do not form acetoin, so they are VP negative. Therefore, the positive VP reaction is characteristic of Enterobacter aerogenes.