MIU (Motility Indole Urea)
DESCRIPTION
Test checks simultaneously for the  production of indole, urea hydrolysis and bacteria motility. Medium, together with TSI and Simmons
agar,  is most used for Enterobacteriaceae identification, especially Escherichia and Salmonella.
MEDIUM PREPARATION
Composition:
MIU base
Proteose peptone Difco ..................................................................................10g
Beef extract ......................................................................................................... 5g
NaCl ..................................................................................................................... 5g
KH
2PO4  .............................................................................................................  2g
Phenol red solution 1/500 ............................................................................ 6 ml
Agar .......................................................................................................................3g
Distilled water ............................................................................................  900ml
Adjust pH to 6.8-6.9

Urea - glucose solution
10 g urea + 1 g glucose + distilled water
ad 100 ml.
Preparation: to 90 ml base medium add 10 ml urea-glucose solution. Other
commercial MIU base media include glucose, and only require 10 ml sol. 40% urea to
be added.

PROCEDURE
Harvest a well isolated colony and inoculate a MIU tube by stabbing the medium.
Incubate at 37 °C, 24 hours.

RESULTS
Motility is positive if the entire medium became opaque (semisolid state of the medium
permits the bacteria moving). Result is negative if the culture grows only on the
stabbing line.
For the indole test add 2-3 drops of Ehrlich-Covacs reactive. A red layer on the surface
of the medium appears if the reaction is positive.
Urea is hydrolysed if the entire medium turns red.
NOTES
Melt base medium by boiling it and wait to cool under  50 ºC before adding Urea - glucose solution, otherwise urea will be inactivated.
Final medium state must be semisolid.
REFERENCES:
1. Helgomar Raducanescu, Valeria.Bica-Popii,1986. Bacteriologie veterinara, Ed. Ceres, Bucuresti.
TSI (left), MIU (middle) and Simmons agar (right)
TSI, MIU & Simmons citrate
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(c) Costin Stoica
A demonstration of TSI, MIU and Simmons utilization is available in video section.
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