I am trying to figure out what this is exactly. We did an MRVP test on E Coli and Enterobacter aerogenes. In the Voges-Proskauer (VP) portion of the test the indicator, Methyl red, turned yellow if acetoin was present. I believe that was because the pH was above 6.0 (acetoin is supposed to be neutral). What I am trying to figure out is what is acetoin? Is it similar to acetone or acetyl CoA?