Principle: Acetate Utilization Test is used to determine if an organism can use acetate as the sole source of carbon. (Another similar test in which organisms ability to utilize Citrate as a sole source of carbon is useful for differentiating the members of Enterobacteriaceae family, this test is called Citrate Utilization test.) If so, breakdown of the sodium acetate causes the pH of the medium to shift toward the alkaline range, turning the indicator from green to blue.
- With a straight inoculating needle, inoculate acetate slant lightly from an 18-24 hour culture. Do not inoculate from a broth culture, because the growth will be too heavy.
- Incubate at 35oC for up to 7 days
- Positive: Medium becomes alkalinized (blue) because of the growth of the organism.
- Negative: No growth or growth with no indicator change to blue.
- Positive: Eschericha coli
- Negative: Shigella flexneri