Unknown Bacteria Report

When given an unknown bacteria there are a multitude of steps one must go through to be able to correctly identify what bacteria was given. It is important to correctly identify the bacteria because some bacteria are more harmful than others. The gram stain is the first test that should be performed because it helps narrow down the possibilities by telling one whether the bacteria is gram positive or gram negative. After this test is performed, one shall place bacteria on/in Mannitol Salt agar, MacConkey agar, Eosin Methylene Blue agar, Urea agar, Simmon’s Citrate, Purple Beef broth with Lactose and finally Purple Beef broth with Sucrose. A streak plate should also be made up, this helps one identify the morphology of the colonies. Once the streak plate has been inoculated, and colonies have grown, the Catalase test would then be performed. After receiving the results from all the tests listed above, it has been concluded that Escherichia Coli was the unknown bacteria. The first and most important test that should be performed on the bacteria is the Gram Stain. This test is a process of using multiple stains to differentiate between Gram Negative and Gram Positive organisms (Microbugz). If a bacterium is Gram Positive the cells will appear purple

It is differential for PH levels and selective for salt. If a bacterium holds a PH level below 6.8 the agar will turn yellow, which was formerly pink when sterile. With a PH level between 7.4 and 8.4 the agar will turn red. If the PH level is above 8.4 the bacteria cannot ferment mannitol, which would mean the agar has no change and stays pink. This medium is selective for salt so if a bacterium is not halotolerant, it cannot grow because of the high salt concentration in the Mannitol Salt agar (Microbugz). The unknown bacterium that was tested was negative for growth and fermentation, with that being said, the agar had no color change and stayed