The purpose is to see if the microbe can ferment the carbohydrate (sugar) glucose (also known as dextrose) as a carbon source.<\/p>\n\n\n\n
If glucose (dextrose )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 glucose (dextrose) broth.<\/a> The medium is a nutrient broth to which 0.5-1.0% glucose ( dextrose ) 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 Additionally, this medium contains a Durham tube, a smaller inverted tube which can serve as a trap for gas bubbles generated during fermentation of sugars. So this same tube would be used to determine whether a microbe could produce gas from the fermentation of glucose\/dextrose.<\/p>\n\n\n\n An inoculum from a pure culture is transferred aseptically to a sterile tube of phenol red glucose (dextrose) 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 glucose broth<\/a> medium. <\/p>\n\n\n\n 2. Complete the process of a tube-to-tube aseptic transfer to inoculate the medium. Forgotten how to do these things? Watch the “Show Me How To” videos.<\/a><\/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. Forgotten how to do these things? Watch the “Show Me How To” videos<\/a>.<\/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 Uninoculated medium: <\/a> <\/p>\n\n\n\n Positive result:<\/a><\/p>\n\n\n\n Negative result:<\/a><\/p>\n\n\n\n 9. Record test result. Forgotten how to do these things? Watch the “Show Me How To” videos<\/a>.<\/p>\n\n\n\nHow is the test performed? <\/h3>\n\n\n\n
What reagents are added? <\/h3>\n\n\n\n
\n\n\n\nPerforming 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
\n\n\n\nVUMIE is the flight simulator of microbiology labs.<\/h2>\n\n\n\n