The titre is defined as high titre of phage which is required for plaque bioassay. In this procedure initially a plaque is cut from a plate and suspended in tryptone broth. After vortexing for 2-3 minutes it allowed to transfer in a overnight grown culture of specific bacteria (E. coli, etc.) and result in the appearance of numerous plaques containing high titre of plaques.
- Tryptone broth
- bacterial culture
- Nutrient agar plates with plaques
- Sterile needle or forceps
- Sterile pipette
- Procure a plate containing plaques
- Scoop out a plaque from the plate
- Meanwhile, prepare an overnight grown bacterial culture
- Mix 0.1 ml plaque broth in 10 ml culture of E. coli .
- Incubate the mixture at 37ºC for 6-8 hours.
- Centrifuge the mixture at 10,000 rpm for 20 minutes to remove the bacterial cells.
- Add a few drops of chloroform for lysing the bacterial cells, if any, present in the suspension.
- Pour the suspension (1-2 ml) on each plate containing nutrient agar.
- Incubate the plates at 37ºC for 24 hours in inverted position.
- Observe the plate for plaque formation.
Numerous plaques (clearings) of uniform shape and size will be visible against the dark back ground of agar.
Dr. R. C. Dubey – Practical Microbiology