Nutrient Ear Lab Report

First the unknown tube was isolated. This was completed by taking an inoculating loop and spreading the unknown out on to a Nutrient Agar plate. This was done using the streak plate method, which is described in the lab manual. The bacterium were incubated and grown at 48 hours. Upon observation the isolation plate showed growth of two different colonies. After the morphology was observed and recorded, a Gram stain was performed on each of the two unknowns, this procedure is found in the laboratory manual. The two microorganisms were identified; one was a Gram-positive rod bacteria, the other was a Gram-negative rod bacteria. A series of biochemical tests were performed based on the results of the Gram stains. The proper procedure …show more content…
After incubation for the SIM test the Kovac’s reagent was added and the top of the broth did not turn a dark red, it was decided that this was a negative test for Indole. With the negative Indole test result this eliminates E. coli and P. vulgaris. The last test I did was use a Urea broth test for #29. The results from this test were negative which means there was no production of urease to break down urea and produce a pH change to trigger the phenol red to turn pink. This outcome eliminated Klebsiella pneumonia as a possibility. The Urea test indication concluded that the Unknown #29 was Enterobacter aerogenes. But for good measure as a Final test I used the Methyl Red-Vogues Proskauer test to double check my results. The MR-VP test was performed, giving the expected negative result. This indicated that the unknown did not produce acids as a byproduct of glucose metabolism. The negative result eliminated K. pneumoniae from the list of remaining possibilities. The Voges-Proskauer test demonstrated a positive result indicating that Enterobacter aerogenes was the unknown bacterium. The positive test indicated that the unknown, E. aerogenes does not produce acetyl methyl