The pathways used to metabolize a sugar under aerobic conditions differ from those used under anaerobic conditions. When oxygen is present , the process is called oxidation , and when oxygen is absent it is called fermentation . This test provides insight into the ability of the bacterium to use glucose by both methods.<\/p>\n\n\n\n
Two tubes of OF glucose<\/a> medium are used, one of which is covered with a layer of sterile mineral oil as an oxygen barrier. If glucose is metabolized in either tube, acidic end products accumulate and the pH drops. A pH indicator in the medium changes color to indicate acid production.<\/p>\n\n\n\n OF glucose<\/a> medium with oil overlay is used. This consists of a nutrient medium to which 1% glucose has been added. Mineral oil lighter in density that the medium is added to provide an airtight barrier. The pH indicator is brom thymol blue, which is green at neutral pH and turns yellow at pH <6.0. It gets its name because it turns blue at pH >7.6.<\/p>\n\n\n\n An inoculum from a pure culture is transferred aseptically to a tube of OF glucose medium<\/a> with oil overlay The agar is stabbed through the oil to “plant” the bacteria in the butt of the tube. The inoculated tube is incubated at 35-37 C for 24 hours. A positive result for fermentation of glucose is indicated by the medium turning yellow.<\/p>\n\n\n\n None.<\/p>\n\n\n\n 1. Select the OF glucose<\/a> with oil overlay 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. Incubate for the appropriate length of time. For this test, 24 hours is sufficient for determining the result. <\/p>\n\n\n\n 8. Retrieve desired incubated culture from the incubator. <\/p>\n\n\n\n 9. Observe test result. If the test was followed as described above, the culture will have changed to yellow in the presence of acids (indicating a positive test) or remain green in the presence of bases\/alkali (indicating a negative test). <\/p>\n\n\n\n 10. Record test result<\/a>. <\/p>\n\n\n\n Uninoculated OF “Oxidation” broth<\/a><\/p>\n\n\n\n Uninoculated OF “Fermentation” broth (oil overlay)<\/a><\/p>\n\n\n\n Positive Oxidation test<\/a><\/p>\n\n\n\n Positive Fermentation test<\/a><\/p>\n\n\n\nWhat medium is used for OF glucose – fermentation? <\/h3>\n\n\n\n
How is the OF Glucose \u2013 fermentation 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
Determination of Test Results<\/h3>\n\n\n\n