Proteus Vulgaris Microbiology

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Proteus vulgaris #12

The importance of identification of a certain microorganisms can range between a life threatening diseases to a creation of certain antibiotic. Understanding the principals of living microbes and identifying my unknown bacteria through numerous biochemical and metabolism tests, with the outmost confidence, Proteus vulgaris had the precise qualifications. The point of this report is to further explore the identification of my unknown bacteria by revealing the results of the experiments and comparing them to the other six known bacteria: Micrococcus luteus, Staphylococcus aureus, Staphylococcus epidermidis, Alcaligenes faecalis, Escherichia coli, and Proteus vulgaris that were used in the lab, as well as comparing and contrasting the actual and factual results. Its unique pink rod shaped morphology was the first step observed under the microscope to identify its unknown characteristic. There were other methods utilized in lab as well: the Mannitol Salt and Eosin Methylene Blue Agar and the tryptic soy broth experiments. Oxygen reaction (aerobic vs. anaerobic), glucose fermentation, oxidase reaction, the catalase test, urea hydrolysis, nitrate reduction experimentation, Kligler’s Iron Agar, the SIM medium test and lastly the IMViC series of tests. All the biochemical tests were carried out in properly supervised manner to compare the unknown bacteria to the six known that were mentioned above. First it was the Gram staining procedure used to categorize bacteria in two groups, gram positive and gram negative. Gram staining is one of the most useful test used in the clinical setting to identify bacterial colonies due to their broad staining spectrum. (Black, 2008, pp. 70-71) The basis of the Gram stain is that gram positive bacteria retains the color of the primary dye, the crystal violet, whereas the gram negative bacteria loses the primary dye once its washed with a decolorizing solution but takes on the color of the counterstaining dye of safranin. (Harley, 2011, p. 46) The significance of Gram staining procedure helped to identify a type of a peptodoglycan cell wall the unknown bacteria had. The choices were between, gram positive, thicker wall with stronger dyes and gram negative, thinner wall with less absorption of dyes. The unknown bacteria revealed to be gram negative rod shaped. The next series of steps that were used to reveal the unknown culture, was the streak plate method used on the Mannitol Salt Agar known as MSA, Eosin Methylene Blue Agar known as the EMB and the liquid tryptic soy broth test. The streak plate method is used to dilute and spread out organisms to form individual colonies. When the sterilized loop full of bacteria glides, individual cells are removed from the loop and are being deposited on top of the agar’s surface. This process gives raise to the separate colonies hence its dilution gradient which is already established on the agar’s surface as the cells get deposited, creates the rise of separation. MSA contains the sugar mannitol and a pH indicator phenol red; in clinical settings it’s used to isolate the bacteria staphylococci. (Harley, 2011, p. 103) Once bacteria is properly streaked on the MSA and incubated, if the bacteria used is staphylococci, it will ferment the mannitol by forming an acidic byproduct, which causes the phenol red in the agar to turn yellow and reveals the growth of that bacteria on top of the agar. (Harley, 2011, pp. 102-103) If the bacterium does not ferment the mannitol, the color does not change, and the growth is not exposed. The results of the unknown bacteria were negative for fermentation, and no growth appeared on the MSA’s surface; therefore, it ruled out the possibility of it being Staphylococcus aureus or Staphylococcus epidermidis. The EMB’s selective and differential medium is widely used in a clinical setting for the detection of a bacterium called Escherichia coli. (Harley, 2011, p. 103) Eosin Y and Methylene blue are pH...
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