Appendix G

Media Glossary
January 2006

Glossary of agars, broths and other reagents

Section I

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Indole Reagent (Kovac's)

Basal Medium
Pure amyl or isoamyl alcohol	150 mL
p-dimethylaminobenzaldehyde	10.0 g
Hydrochloric acid (HCl), concentrated	50.0 mL

Complete Medium:

Dissolve p-dimethylaminobenzaldehyde in amyl or isoamyl alcohol. Slowly add HCl. Store at 4°C. To test for indole, add 0.2-0.3 mL reagent to 5 mL of 24 h bacteria culture in tryptone broth. Dark red color in surface layer is positive test for indole.

Indole Reagent (for MFHPB-27)

Basal Medium
p-dimethylaminobenzaldehyde (DAB)	0.5 g
1N Hydrochloric acid (HCl)	100.0 mL

Complete Medium:

Dissolve DAB in 1N HCl and store in the dark below 20°C. The reagent is stable for at least 2 weeks. New lots of DAB must first be checked against a known indole producing E. coli, before use with unknown samples.

Iodine Solution (Gram's)

Basal Medium
Iodine	1.0 g
Potassium iodide	2.0 g
Distilled water	300 mL

Complete Medium:

Dissolve potassium iodide in distilled water. Add iodine crystals slowly and stir until dissolved. Filter into a brown bottle which has a tight closure. Keep away from light.

Iodine Solution (Lugol's)

Basal Medium
Iodine	5.0 g
Potassium iodide	10.0 g
Distilled water	100 mL

Complete Medium:

Dissolve potassium iodide in distilled water. Add iodine crystals slowly and stir until dissolved. Filter into a brown bottle which has a tight closure. Keep away from light.