Unknown Laboratory Report

Sarah Mansfield

Biology 203

Professor Lana

November 19, 2014

INTRODUCTION

Microorganisms are the earliest forms of life and most have thrived since the early birth of the planet. They have evolved into many different forms of life such as animals, humans, and plants. While some microorganisms impact life in a positive way by sustaining life, others cause disease and even death (Nester, et al. 2012). Prokaryotes are one of the earliest organisms to exist, and many of these organisms can thrive in conditions far worse than other living things. For example, they can tolerate extreme temperatures, acidic, or alkaline environments (Foster 1996). Prokaryotic cells do …show more content…
The 12A bacteria were added to the tube by stab inoculation. The tube was incubated at 370 C for at least 24 hours. The results showed that the color of the medium was black with (+) H2S production. The unknown was determined to be positive for motility ( Stevenson University 2011). The next test performed was the nitrate reduction test on bacteria 12A. Nitrate reduction is determined by cultivating organisms in nitrate broth. Loop inoculation was used to transfer the organism into the tube. Reagent A and B were added to the medium to check for nitrate. The medium turned red, indicating a positive test ( Stevenson University 2011). The urease test was performed on bacteria 12A to test for the breakdown of urea. Urease positive bacteria will turn the broth a bright pink color. Urease is a test that is helpful in identifying the bacteria Proteus vulgaris ( Stevenson University 2011). Loop inoculation was used to transfer the bacteria into the urea broth tube. The test revealed a bright hot pink color showing a positive …show more content…
The possibilities were Pseudomonas aeruginosa, Escherichia coli, Salmonella typhimurium, Proteus vulgaris, Alcaligenes faecalis, Enterobacter aerogenes, and Klebsiella pneumonia. The first test performed to narrow down the unknown bacteria 12A was the Indole test. The unknown bacteria was cultured in a medium that contains tryptophan. This amino acid is broken down, and indole is then released. Indole production is detected by the Kovac’s reagent. The Indole test on 12A showed a positive result. This positive result eliminates Salmonella typhimurium. The second test performed on the 12A unknown was the Methyl red test. This was to determine if the bacteria could produce acids from glucose fermentation. After adding the methyl red reagent, the liquid turned red in color. This meant a positive result for this test. The positive result on the Methyl Red test eliminates the bacteria P. aeruginosa and Enterobacter aerogenes. Next, carbohydrate tests were conducted on the unknown bacteria 12A. The bacteria was able to ferment glucose and sucrose but did not ferment lactose. The next test that was performed on the gram-negative bacteria was H2S Production which showed a positive result. Enterobacter aerogenes, Pseudomonas aeruginosa, Klebsiella pneumonia, and Alcaligenes faecalis bacteria test negative for H2S Production. The nitrate test was used to see if the bacteria would reduce nitrate. The