Isolation and Identification of Unknown Bacteria Performed: 10 November 2000 through 19 November 2000 The purpose of this lab was to identify and isolate two unknown species of bacteria from one broth culture. Testing materials were supplied to help in the successful completion of this experiment.Materials and MethodsWeek 1, Day 1 (10 November 2000)The first day an unknown sample was assigned to each group of students. The first test applied was a gram stain to test for gram positive or gram-negative bacteria. The morphology of the two types of bacteria was viewed under the microscope and recorded. Then the sample was put on agar plates using the quadrant streak method for isolation. There were three agar plates; one was incubated at room temperature, the second at 30 degrees Celsius, and the third at 37 degrees Celsius. By placing each plate at a different temperature optimal growth temperature can be predicted for both species of bacteria.Week 1, Day 2 (12 November 2000)After 48 hours of incubation the agar plates were viewed. Individual colonies were tested for successful isolation by gram staining and then viewing the stained bacteria under a microscope. Isolation was successful. One colony of each unknown bacteria was transferred to an agar slant for growth. The agar slants were stored at room temperature over the weekend so that they would not grow too much.Week 2, Day 1 (17 November 2000)After 5 days of growth each slant was tested using the gram staining technique to confirm the complete isolation of the bacteria. Both isolations were completely successful. Then each sample of bacteria was subjected to a series of tests for identification. One bacterium was gram negative. It underwent four different tests. These tests were the EMB test (Eosin Mehylene Blue), the Sulfur Indole Motility (SIM) test, the Urease test, and the Simmon’s Citrate Utilization test. The EMB test checks for a bacteria’s ability ...
