Test Catageory
فئة التحليل
Microbiology
Refrence Books
كتب مراجع
1. Bailey & Scott’s Diagnostic Microbiology
2. Laboratory Manual and Workbook in Microbiology
Skills Required
المهارات المطلوبة
1. Inoculation
2. Layering technique
3. Color interpretation
Video Resources
مصادر فيديو
Principle
Tryptone broth contains tryptophan substrate. Bacteria with tryptophanase enzyme degrade tryptophan, releasing indole. Adding Kovac’s reagent produces a red color indicating indole presence. No color change occurs if indole not produced.
Solutions & Equipments
1. Tryptone broth
2. Bacterial isolate
3. Kovac’s reagent
4. Test tubes
5. Loop
Sample Type
Pure bacterial isolates from primary culture requiring identification.
Procedure
1. Inoculate tryptone broth and incubate 24 hours
2. Add Kovac’s reagent gently down side of tube
3. Observe for distinct red color band in alcohol layer
Results
No color change = negative
Red color band = positive
Interpretation
Determine indole production capability
Use to identify species based on indole result pattern
Notes:
1. Check known positive/negative control strains
2. Do not over-incubate old cultures
3. Properly layer added reagent
M. Sulieman
mohammad@mlsgaate.com
The indole test detects the ability of bacteria to break down tryptophan amino acid and produce indole as a byproduct.
