Why TCBS agar is not autoclaved?

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Last Updated on January 20, 2021 by Sagar Aryal

Why TCBS agar is not autoclaved


Thiosulfate-citrate-bile salts-sucrose (TCBS) Agar is used for the selective isolation of Vibrio cholerae and other enteropathogenic vibrios. TCBS agar is composed of yeast extract, peptone, sodium thiosulfate, sodium citrate, ox bile (oxgall), sucrose, sodium chloride, iron (III) citrate, bromothymol blue, thymol blue, agar, and distilled or deionized water. TCBS is not autoclaved because:

  • This media contains Ox bile (Oxgall), a derivative of bile salts which inhibit gram-positive bacteria might be sensitive while autoclaving.
  • This agar needs to be boiled and not autoclaved to avoid the caramelization (browning) of sucrose.
  • Autoclaving may precipitate and/or alter the chemistry of the media.


  1. https://www.researchgate.net/post/Why_is_TCBS_media_for_culturing_Vcholerae_not_supposed_to_be_autoclaved_autoclave.
  2. https://microbiologyinfo.com/thiosulfate-citrate-bile-salts-sucrose-tcbs-agar-composition-principle-uses-preparation-and-colony-morphology/
  3. https://www.sciencedirect.com/science/article/pii/S007963520380098X
  4. https://www.chegg.com/tutors/Microbiology-questions/why-we-cannot-autoclave-TCBS-agar–V5TUV/
  5. https://aem.asm.org/content/62/9/3548.full.pdf
  6. https://microbenotes.com/thiosulfate-citrate-bile-salts-sucrose-tcbs-agar/

1 thought on “Why TCBS agar is not autoclaved?”

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