The Cragie tube or Craigie tube is a method used in microbiologyTextbook of Microbiology by Ananthanarayan and Panikar, for determining

bacterial motility Bacterial motility is the ability of bacteria to move independently using metabolic energy. Most motility mechanisms which evolved among bacteria also evolved in parallel among the archaea. Most rod-shaped bacteria can move using their own ...

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Technique

A hollow tube with some

culture medium A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss ''Physcomitrella patens''. Differe ...

is placed in semi-solid agar inside a bottle. 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.

Observation

On examining the areas where bacterial growth has occurred there are several observations to be made: *the colonies of the

non-motile bacteria Non-motile bacteria are bacteria species that lack the ability and structures that would allow them to propel themselves, under their own power, through their environment. When non-motile bacteria are cultured in a stab tube, they only grow along ...

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.

Technique

Observation

References

See also