VetBact logo


Swedish University of Agricultural Sciences

Veterinary bacteriology: information about important bacteria
Veterinary bacteriology

Show all growth media

Tryptic soy agar (TSA) + VRG

Tryptic soy agar (TSA)

The image shows a combined TSA and VRG agar plate. On plate A, no bacteria have been streaked out, while Escherichia coli has been streaked out on plate B. - Click on the image to enlarge it.


"Tryptic soy agar (TSA)" is a general medium, which is used for isolation and enumeration of many different bacteria, among others, E. coli.

The medium contains:

  • casein peptone (contains amino acids and peptides)
  • soya peptone (contains amino acids and peptides)
  • NaCl (contributes to the osmotic balance)
  • agar (gelifying agent)
  • water

The final pH of the medium should be 7.3.

Other comments:

TSA is often used in combination with VRG agar. TSA is then mixed with the sample to be analyzed at around 40°C and poured into the plates. After preincubation for 1-2 h at ambient temperature, the TSA is overlayed with VRB agar and the incubation is then continued at 37°C.

Updated: 2023-05-31.


The revised taxonomy of the mollicutes (mycoplasmas)

About 2 years ago, the taxonomy of mycoplasmas was revised at VetBact, because a research group had proposed that 5 new genera should be included together with the genus Mycoplasma. This also had consequences for higher taxa within the phylum, which was then called Tenericutes. Now another group of researchers has suggested that the new names should be rejected.

Published 2023-10-03. Read more...

Recently Updated

Recent blog posts

Swedish University of Agricultural Sciences