Why TCBS agar is not autoclaved?

Why TCBS agar is not autoclaved

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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/

About Author

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Sagar Aryal

Sagar Aryal is a microbiologist and a scientific blogger. He is doing his Ph.D. at the Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal. He was awarded the DAAD Research Grant to conduct part of his Ph.D. research work for two years (2019-2021) at Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS), Saarbrucken, Germany. Sagar is interested in research on actinobacteria, myxobacteria, and natural products. He is the Research Head of the Department of Natural Products, Kathmandu Research Institute for Biological Sciences (KRIBS), Lalitpur, Nepal. Sagar has more than ten years of experience in blogging, content writing, and SEO. Sagar was awarded the SfAM Communications Award 2015: Professional Communicator Category from the Society for Applied Microbiology (Now: Applied Microbiology International), Cambridge, United Kingdom (UK). Sagar is also the ASM Young Ambassador to Nepal for the American Society for Microbiology since 2023 onwards.

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

  1. Taxonomy Of Bacteria is a dynamic science. Can you explain how? Please send me answer to my mail if possible


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