Unknown Bacteria Lab Assignment

The purpose of the unknown bacteria lab assignment was to select an unknown bacteria culture and, through a series of metabolic tests, identify which bacteria genus resided in the pure culture received. A nutrient broth inoculated with bacterial culture (numbered 45, henceforth referenced as U45) was selected and a streak plate was made to isolate a pure culture for use throughout the assignment. From the streak plate, several slides were made to determine the morphology of unknown 45. A Gram stain, used to indicate the type of cell wall possessed by the bacterium, was performed. U45 stained a bright pink color and were small ovals and rods in shape. This indicated that U45 was a gram-negative bacillus bacterium. A capsular stain was then performed to determine the presence or absence of a capsule. Unknown 45 was positive for capsules. Having determined that U45 was gram-negative, there was no need to perform the Schaeffer-Fulton endospore stain, which is used detect the presence of endospores in certain gram-positive bacteria.
The following metabolic tests were performed on U45 based on instruction given in Microbiology Lab Manual by John P. Harley, and by the instructor:
1. Carbohydrate fermentation
2. Sulfide Indole Motility (SIM) test
3. …show more content…
IMViC contains a series of four tests: Indole, Methyl red, Voges-Proskauer, and Citrate utilization. The indole portion of this test will not be performed since U45 was determined indole negative with the SIM test. The methyl red portion of the IMViC tests utilizes methyl red as a pH indicator and indicates whether a microbe uses the mixed acid fermentation pathway. If the pH falls to 4 or lower (acidic), the indicator turns red, signaling a positive result. If the pH rises to 6 or above, the indicator turns yellow, signifying that the microorganism is negative for mixed acid production. U45 was negative for mixed acids