The purpose is to see if the microbe can hydrolyze the compound esculin as a carbon source.<\/p>\n\n\n\n
When microbes metabolize esculin in a nutrient medium, the dark brown compound esculetin is produced and the medium is obviously discolored.<\/p>\n\n\n\n
Usually, the medium used is bile esculin agar slant<\/a>. This is a nutrient agar-based medium containing 0.1% esculin and 10% bile salts, and allowed to solidify at a slant. The bile salts inhibit some bacteria, and so the ability to grow in the presence of bile salts represents a second test use for the medium.<\/p>\n\n\n\n An inoculum from a pure culture is transferred aseptically to a sterile tube of bile esculin agar<\/a> and streaked along the slant. There is no need to stab the medium. The inoculated tube is incubated at 35-37 C for 24 hours and the results are determined. Abundant growth on the slant indicates a positive test for growth in the presence of bile. If growth is present, esculin hydrolysis can be observed if the medium has taken on an intense, chocolate brown coloration.<\/p>\n\n\n\n None.<\/p>\n\n\n\n 1. Select the bile esculin agar slant<\/a> medium. <\/p>\n\n\n\n 2. Using an inoculating wire, complete the process of a tube-to-tube aseptic transfer<\/a> to inoculate the medium by streaking the slant and stabbing the butt of 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. Observe test result. The change of all or a significant portion of the medium to a chocolate brown indicates breakdown of esculin to esculetin, a positive test. Negative results would be indicated by growth on the slant but no change from the normal amber color of the medium. <\/p>\n\n\n\n 8.\u00a0Record test result<\/a>. \u00a0<\/p>\n\n\n\n Uninoculated Bile Esculin Agar Slant<\/a><\/p>\n\n\n\n Positive for Growth on Bile and Positive for Esculin Hydrolysis<\/a><\/p>\n\n\n\n Positive for Growth on Bile but Negative for Esculin Hydrolysis<\/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