This test determines whether the microbe produces indole from the amino acid tryptophan.<\/p>\n\n\n\n
If indole is produced, it will react with a chemical reagent added after incubation to produce a color change.<\/p>\n\n\n\n
There are two media that are used for this test: Sulfide-Indole-Motility (SIM) medium and Tryptone broth<\/a> medium. This program uses the Tryptone broth medium. SIM is a nutrient medium which allows the detection of three different traits in bacteria: it contains sulfates to serve as the substrate for detecting sulfide (H2S) production; abundant tryptophan as a substrate for indole production; and its content of 0.5% agar limits bacterial swimming, thereby allowing detection of motility. Tryptone broth<\/a> serves the same purpose as SIM as far as indole production is concerned, and the means for conducting the test and interpreting results remain the same as SIM.<\/p>\n\n\n\n An inoculum from a pure culture is transferred aseptically to a sterile tube of SIM or tryptone broth<\/a>. An inoculating wire should be used for inoculating SIM and a loop or wire for tryptone broth . SIM should be stabbed all the way to the butt carefully to disturb the medium as little as possible. The inoculated tube is incubated at 35-37 C for 24 hours.<\/p>\n\n\n\n Five to ten drops of Kovac’s<\/a> reagent are added to the tube. The reagent does not mix with water and forms a thin layer above the agar or broth. The reagent reacts with indole to produce a ring that is cherry red in color.<\/p>\n\n\n\n 1. Select the tryptone broth<\/a> medium. <\/p>\n\n\n\n 2. Complete the process of a tube-to-tube aseptic transfer<\/a> to inoculate the medium.<\/p>\n\n\n\n 3. Place the inoculated tube into the 35-37 C incubator. <\/p>\n\n\n\n 4. Press the New Day button<\/a> to move forward 24 hours.<\/p>\n\n\n\n 5. Incubate this test for only 24 hours. <\/p>\n\n\n\n 6. Retrieve the incubated culture from the incubator.<\/p>\n\n\n\n 7. This is a test that requires addition of reagents to bring about the change in appearance of a positive test. Select the dropper tool and the appropriate reagent needed from the chemical shelf. For this test, select Kovac\u2019s<\/a>. <\/p>\n\n\n\n 8. Remove the cap from the tube. <\/p>\n\n\n\n 9. Place the end of the dropper into the tube and add the reagent to the culture. <\/p>\n\n\n\n 10. Observe test result. For this test, addition of the appropriate reagent produces a cherry-red ring floating above the culture medium if the test is positive. If negative, the ring that forms is yellow or amber. <\/p>\n\n\n\n 11.\u00a0Record test result<\/a>.<\/p>\n\n\n\n Uninoculated Tryptone Broth:<\/a><\/p>\n\n\n\nHow is the test performed? <\/h3>\n\n\n\n
What reagents are added? <\/h3>\n\n\n\n
Performing this test in the VUMIE Online lab<\/h2>\n\n\n\n
Inoculation of Medium<\/h3>\n\n\n\n
Incubation of the Inoculated Medium<\/h3>\n\n\n\n
Addition of Reagents<\/h3>\n\n\n\n
Determination of Test Results<\/h3>\n\n\n\n