The purpose is to see if the microbe can ferment the carbohydrate xylitol as a carbon source.<\/p>\n\n\n\n
If xylitol is fermented to produce acid end products, the pH of the medium will drop. A pH indicator in the medium changes color to indicate acid production.<\/p>\n\n\n\n
Several media are available for this. Most commonly used is phenol red xylitol broth<\/a>. The medium is a nutrient broth to which 0.5-1.0% xylitol is added. The pH indicator phenol red is red at neutral pH but turns yellow at pH < 6.8. It also changes to magenta or hot pink at pH >8.4.<\/p>\n\n\n\n An inoculum from a pure culture is transferred aseptically to a sterile tube of phenol red xylitol broth<\/a>. The inoculated tube is incubated at 35-37 C for 24 hours and the results are determined. A positive test consists of a color change from red to yellow, indicating a pH change to acidic.<\/p>\n\n\n\n None.<\/p>\n\n\n\n 1. Select the phenol red xylitol 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. No reagents are required for completion of this test. <\/p>\n\n\n\n 8. Positive tests will be yellow; negative results are any other color.<\/p>\n\n\n\n 9. Record test result<\/a>.<\/p>\n\n\n\n Uninoculated medium: <\/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
Determination of Test Results<\/h3>\n\n\n\n