Identifying an Unknown Organism

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Unknown Microorganisms
May 1, 2013
This paper is based on an experiment done in the laboratory over a period of time using the standard method of identifying an unknown microorganism relying on features such as morphology, arrangements and biochemical reactions. It was done in succession with each step complimenting the other. At the end of the experiment three microorganisms Bacillus azotoformans, Staphylococcus aureus, and Escherichia coli was identified and one result was inconclusive. The focus of this paper will be on the description of the just one of the three bacteria and some of its effects on humans. The first test done was a differential stain (gram stain) to determine the unknown microorganism cell shape and arrangement. The gram staining is done by first putting a sample of the unknown bacteria on a slide and it was heat fixed taking care not to over or under fixed the slide. The slide was flooded with crystal violet and let stand for 30 seconds and then rinsed with water. Secondly, the slide was treated with a decolorizing agent (ethanol) and after a minute it was washed with water and countered stain with safranin and within a minute it was rinsed with water dried and viewed under a light microscope. The cell was identified as a gram negative rod shape microorganism. Having identified the morphology of the unknown microorganism the unknown microorganism flow chart was referred to leading us to our next test the Eosin-methylene blue or EMB test. This test is used to differentiate between lactose fermenting gram negative bacteria based on their acid production. This test was performed by first dividing the EMB plate into four quadrants and each quadrant was labeled corresponding to the four unknown microorganism and using aseptic technique each quadrant was inoculated with bacterial cultures and incubated at 37 degrees Celsius. After few days later the experimental plate was compared to the control plate for lactose fermentation. Of the four...
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