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Vibrio cholerae on TCBS agar |
Colonies of V. cholerae on TCBS agar are large (2-4 mm) and yellow because of the fermentation of sucrose. They are characteristically round, smooth, glistening, and slightly flattened (see colonies in detail).
TCBS is the medium of choice for the isolation of V. cholerae and is widely used worldwide. TCBS agar is commercially available and easy to prepare, requires no autoclaving, and is highly differential and selective. It is not suitable for direct testing with V. cholerae O1 antisera.
Bile salts (oxgall) and sodium citrate inhibit gram-positive bacteria and coliforms. Sodium thiosulphate serves
as a good source of sulphur, which in combination with ferric citrate detects the production of hydrogen sulphide. Vibrio sp. that is able to utilize sucrose will
from yellow colonies. Bromothymol blue and thymol blue are the pH indicators.
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Microscopy:
Gram-negative, curved, non-spore-forming rods. |
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