Motility is the capability of an organism to move by itself by method of propeller-like flagella distinctive to bacteria or by distinct fibrils that produce a gliding form of motility. Motile bacteria move using flagella, thread favor locomotor appendages extending outward native the plasma membrane and also cell wall surface either solitary flagellum or lot of flagella. Motility has actually long been recognized as an important taxonomic tool and also biological properties of microorganisms. The presence of flagella occurs mostly in bacilli yet there are a few flagellated cocci, hence motility is a an extremely important way of to know in the family Enterobacteriaceae. Indigenous the beforehand days in the ar of microbiology, the ability of bacteria come move has actually been offered as a method of differentiation and also classification the organisms.

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To determine the motility the bacterium.To differentiate in between motile and non motile bacteria.


Motility by bacterium is greatly demonstrated in a semi hard agar medium. In semi-solid agar media, motile bacteria ‘swarm’ and also give a diffuse spreading development that is easily recognized by the nude eye.The medium largely used because that this purpose is SIM medium (Sulphide Indole Motility medium) which is a mix differential tool that exam three various parameters, Sulfur Reduction, Indole Production and also Motility. This media has actually a really soft consistency that allows motile bacteria to move readily through them resulting in cloudiness. The inoculum is stabbed into the center of a semisolid agar deep. Bacter motility is apparent by a diffuse zone of expansion extending the end from the line of inoculation. Part organisms grow throughout the entire medium, whereas rather show small areas or nodules that thrive out from the line of inoculation. The non-motile bacteria will certainly only thrive in the soft agar tube and just the area whereby they room inoculated.


SIM Medium

Pancreatic digest that casein 20.0g, Peptic digest of pet tissue 6.1g, Agar 3.5g, Fe(NH4)2(SO4)2·6H2O 0.2g, Na2S2O3·5H2O 0.2g, pH 7.3 ± 0.2 in ~ 25°C


Touch a directly needle to a swarm of a young (18- come 24-hour) culture growing on agar medium.Stab as soon as to a depth of just 1/3 come ½ inch in the middle of the tube. Be sure to store the needle in the very same line it gone into as it is eliminated from the medium.Incubate in ~ 35°-37°C and also examine daily for up to 7 days.Observe because that a diffuse zone of expansion flaring the end from the line of inoculation.

Expected Results

Positive: Diffuse, hazy growth that spread throughout the tool rendering it contempt opaque.Negative: Growth the is confined to the stab-line, through sharply characterized margins and also leaving the bordering medium plainly transparent.



It is offered for the differentiation of microbe on the communication of motility in a laboratory setting.It is performed to assign taxonomic group to organisms.Motility tests are vital in characterization of pathogens.The exam are often employed in to know protocols in the family EnterobacteriaceaeMotility test is likewise used because that the species differentiation of gram optimistic cocci, Enterococci. Enterococcus faecium and E. Faecalis are non-motile, whereas E. Gallinarum and E. Casseliflavus/E. Flavescens generally space motile.

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Some organisms will not display sufficient growth in this medium to make specific determination, and extr follow-up testing is required.It is recommended the biochemical, immunological, molecular, or fixed spectrometry trial and error be perform on swarms from pure society for complete identification.False-negative reactions may happen if bacter flagella space damaged as result of heating, shaking, or various other trauma. Such eco-friendly shock will certainly render the biology non-motile.Organisms which room weakly motile may result in false-negative reactions.When inoculating semi-solid media, it is essential that the inoculating needle be eliminated along the specific same line used to inoculate the medium. A fanning motion may result in development along the stab line the may an outcome in false-positive interpretation.


Tille, P. M., & Forbes, B. A. (2014). Bailey & Scott’s diagnostic microbiology (Thirteenth edition.). St. Louis, Missouri: Elsevier.Cappuccino J.G. And Sherman N. 2008. Microbiology: A activities Manual, 8 hours ed. Pearson Benjamin Cummings, mountain Francisco, CA,