Unknown Bacterial Overarching Experiment

At the beginning of the semester, samples of bacteria were obtained from various sources. Two bacterial colonies were isolated from plates that were incubated in the lab and these bacteria became the basis for this project. The bacterial cultures were maintained and used for various physiological, cultural, and biochemical tests and observations over several weeks. The purpose of culturing bacteria over half the course of the semester was to learn various techniques used in microbiology labs and to subsequently utilize those techniques for the purpose of identifying the bacteria. The data, once compiled, was then used to determine the possible identity of the unknown bacteria based on the information found in Bergey’s Manual of Systematic
First, carbohydrate fermentation was tested in various sugar solutions (glucose, sucrose, arabinose, mannitol, lactose, and galactose) for the unknown. Cells were taken from culture and inoculated into vials filled with a phenol red sugar solution and a filled Durham tube which was turned upside down. The cells were left to grow overnight and observed the next day for color changes and bubble production which gave positive results for carbohydrate fermentation. The next test was a Methyl Red-Vogues Proskauer (MR-VP broth) test for which a sample of the unknown was inoculated into two separate tubes (one for the MR and one for the VP tube) and allowed to grow for at least 24 hours. Next the MR tube was given a methyl red reagent and mixed to observe a color change to bright red. For the VP tube, 7 drops of Barrit’s A solution and 7 drops of Barrit’s B solution were added to each, mixed, allowed to sit for 5 minutes, and repeated for up to 20 minutes for observation of a deep red color change. The next test was a Triple Sugar Iron (TSI) test. The unknown was inoculated into a TSI slant by stabbing the specimen into the butt using a needle and then streaking on the surface of the agar. The sample was allowed to incubate for 24 hours and read for results. The next test was the citrate utilization slant which examines the ability for a bacteria to use citrate as the sole carbon and energy source. The citrate agar tube was inoculated with the bug by using a needle and then streaking over the surface of the slant. Upon an incubation period of 48 hours, the slant was observed for color change. Next was an oxidase test: cells were taken from the culture using a cotton swab and the sample was covered in an oxidase test reagent and allowed to sit for 30 seconds. Results were then observed and recorded. Following