Acetate Utilization test
This test is used to differentiate an organism capable of using acetate as the sole source of carbon. Organisms capable of using sodium acetate grow on the medium, resulting in an alkaline pH, turning the indicator from green to blue.
With a straight inoculating needle, inoculate acetate slant
lightly from an 18- to 24-hour culture. Do not inoculate from a
broth culture, because the growth will be too heavy.
Incubate at 35°C to 37°C for up to 7 days.
Positive: Medium becomes alkalinized (blue) as a result of the
growth and use of acetate
Negative: No growth or growth with no indicator change to blue
Some strains of E. coli may use acetate at a very slow rate or not at all, resulting in a false negative reaction in the identification process.
Bailey & scotts