Gram Negative Unknown Lab Report

1966 words 8 pages
Abstract The main idea of this experiment was to correctly identify the unknown bacteria, #3. Identification of unknown bacteria yields multiple benefits in many different areas in the research of microorganisms. In this experiment I performed many different test dealing with things such as the presence of enzymes, fermentation abilities and different chemical reactions. Observations made from the tests were then compared to a gram negative unknown chart in order to identify the bacteria. Based off of my results and the chart, I concluded the bacteria #3 was the bacteria Escherichia coli. E. coli is most commonly found in the intestines of warm blooded organisms. Most E. coli strands are non pathogenic however, there are strands …show more content…

The third test that the SIM test is for is motility. If the bacteria is motile then cloudiness will be seen in the medium and if not the bacteria will only be located where it was stabbed. The Citrate Test was used to test for the ability of a bacteria to utilize citrate as a sole source of carbon, these bacteria produce citrate permease which can transport citrate into the cell and make pyruvate from it. Bacteria that can utilize the citrate causes the media to become more alkaline. The indicator for this test is bromythmol blue dye which will turn from green to blue if pH is at 7.6 and above. A blue color change yields a positive result. I inoculated the TSIA (Triple Sugar Iron Agar) Slant with bacteria from my TSA plate using an inoculating loop. The medium was then incubated at 37 degrees Celsius and checked after eight hours of incubation and again after 24 hours of incubation. This test is a differential that tests for sugar utilization, gas production and sulfur reduction. It contains lactose, sucrose and glucose and phenol red as an indicator. No color change means that no sugars were fermented. If there is as bubble or splittin in the medium than a gas was produced and a black color signifies hydrogen sulfide production. The media has sodium thiosulfate as a reducible sulfur and ferrous sulfate as the hydrogen sulfide indicator.
The Gelatin test was solid after placing the medium in the cold


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