Deoxycholate Agar (DOC):
- To isolate and differentiate between various members of the family Enterobacteriaceae.
- DOC contains sodium deoxycholate and citrate which work to inhibit the growth of Gram-positive organisms.
- The medium also contains the sugar lactose, which serves to differentiate among enterics that ferment and do not ferment lactose.
- Fermentation of lactose appears as a red color due to the pH indicator neutral red, which is included in the medium.
- Neutral red is colorless above pH 6.8 and red below 6.8.
The plate here shows common reactions observed on a DOC plate. The reactions are as follows:
A. Heavy lactose fermentation
B. Reduced growth of a Gram-positive organism
C. No lactose fermentation
D. Light lactose fermentation
Deoxycholate Agar
