Cragie tube

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It is a method of determining bacterial motility.Instruments used specially in Microbiology are as follows: ^[1][2]

[edit] Technique

A hollow tube with some culture medium is placed in semi-solid agar inside a bottle. Now a sample of the bacterium to be tested is inoculated into the medium in the hollow tube and the setup is incubated at 37° C overnight.

[edit] Observation

On examining the areas where bacterial growth has occurred we find that:-

• the colonies of the non-motile bacteria remain confined within the tube at the site of inoculation
• the motile bacteria swim out from the bottom of the tube and colonize the surrounding medium as well

Confirmation may be obtained by subculture and retesting.

[edit] References