Gram Stain Lab Report

The tests explained above and completed to aid in the determination of the unknown bacteria were completed in a specific order which was supported with rationale and logic. A T – streak method was completed in succession to obtain a pure isolated colony. The T – streaks were completed with nutrient agar to give the organism nutrients and allow the organism to grow. Once a pure isolated colony was obtained, a Gram stain was completed which gave the Gram reaction and morphology of the bacteria.

The first tests were completed due to the level of difficulty being low. The steps and procedures needed to complete the IMViC (Indole Production, Methyl Red and Voges – Proskauer, and Citrate Utilization) tests were easy to follow and provided in the Microbiology lab manual on pages 82 – 85 (Weaver and Tart, 1999, pg. 82 - 85). Carbohydrate fermentation in the bacteria were performed as well as other metabolic assays as described in the Microbiology lab manual. Following the results of the tests listed above, various fermentation and decarboxylase tests were completed to ensure the identity of the bacteria.

Figure 1 above illustrates a dichotomous key. The dichotomous key above depicts which organisms are Gram negative or Gram positive. Based on each Gram reaction, the bacteria are further separated

Each test completed demonstrated accurate inoculation and results were obtained. There was a test in this experiment which needed to be repeated as the test result obtained did not seem to be accurate. The Phenol Red Lactose test was repeated as the first experimental result illustrated a red medium although the medium was a yellow color in the Durham tube. A second Phenol Red Lactose test was completed and the same results obtained. Due to the same results being obtained after numerous trials, the result of the test was determined to be