Bile Aesculin Medium is generally used for the differentiation and presumptive identification of Group D streptococci (enterococci).
Enterococci hydrolyse aesculin forming, amongst other products, aesculetin which in turn combines with Ferric ammonium citrate producing a dark brown or black complex.
The presence of Bile salts in the medium inhibits gram positive organisms other than enterococci.
The medium can also be used for the presumptive identification of certain organisms within the Enterobacteriaceae group such as Klebsiella spp., Enterobacter spp., etc.
Bile Aesculin Agar
Additional Information
| Container | |
|---|---|
| Shelf Life (days) | |
| Storage Temp (°C) | |
| Dehydrated Medium Appearance | |
| Prepared Medium Appearance | |
| Dehydrated Medium Colour | |
| Prepared Medium Colour | |
| Dehydrated PH | |
| Prepared PH | |
| Recommended Incubation |
Product Description
| Organisms | Ref. No | Result |
| Enterococcus faecalis | NCTC 12697 | Growth, colonies with black centre and blackening of media around colony |
| Escherichia coli | NCTC 12241 | Inhibited |
Formula*
| g/L | |
| Peptone | 14.0 |
| Bile Salts | 15.0 |
| Ferric Ammonium Citrate | 0.5 |
| Esculin | 1.0 |
| Agar | 14.0 |
| Total | 44.5 |
| *Adjusted/supplemented as required to meet performance requirements |
Preparation
Suspend 44.5g of the medium in 1 litre of deionised / purified water. Allow the medium to soak whilst mixing for 10 minutes. Sterilise at 121°C for 15 minutes with frequent stirring to completely dissolve the medium. Cool to 45-50°C, homogenize gently and dispense into appropriate sterile containers.