The Voges-Proskauer test distinguishes which organisms exploit the butylene glycol pathway and also create acetoin. Completion of the Voges-Proskauer test is dependent upon consumption of glucose which releases acetoin (acetymethylcarbinol). As the glucose ferments it also produces 2,3-butanediol. The test is executed by adding alpha-naphtol and potassium hydroxide to the MR-VP broth with the bacteria already in the broth. A positive result is evidenced by a cherry-red colored result2.
Organisms that ferment glucose:
E. coli ferments glucose, S. Epidermidis does not ferment glucose Organisms producing acid byproducts:
S. Epidermidis produces acetoin. E. coli produces various acid by products however, does not produce acetoin. Different biochemical pathways:
Glucose is mainly metabolized by the 10-step pathway called glycolysis (glycolytic). Other pathways include glycogenesis, Enter-Doudoroff, Oxidative pentose phosphate, Hetrotrophic, and finally fermentation. The end result of each and every pathway is the production of pyruvate. Each organism must have a different biochemical pathway. A biochemical pathway has to be able to metabolize glucose. A reason that there are different pathways is simply that there are different environments. A pathway designed for an oxygenate environment, while not be able to metabolize glucose in a non-oxygenated environment. Therefore the organisms had to adapt their metabolic pathways to adapt to the environment that they are in3.