Knowing the Unknown Identifying microorganisms can provide information on diagnosing diseases and discovering the most beneficial treatment possible. The purpose of this assignment was to identify an unknown microorganism using biochemical tests and various methods that were learned in my microbiology laboratory classes. In this paper, I will discuss the processes of how I came to identify my unknown microorganism. For this experiment, I utilized unknown number three which I later identified as Staphylococcus epidermis. I concluded that the unknown organism was Staphylococcus epidermis based on numerous tests performed in the laboratory which I will discuss in detail throughout this paper.
It was determined using Thioglycollate agar deep the unknown culture was inoculated using a stabbing technique, and it was determined that the bacteria is facultative. The bacterium was also inoculated in glucose phenol red fermentation broth and lactose phenol red fermentation broth. Both tubes started red and the turned yellow if acid is present. So when the bacterium ferments it produces an acid and the phenol red turns yellow. There is also a small inverted tube that is placed inside of the tube which indicates whether gas was produced.
* Culture in nutrient broth. This allowed all isolated microbes to grow. * Plate sample onto urea plates. On these plates urea was the only nutrient available, this meant that any bacteria that grew could degrade urea. * Perform urease test.
Taking a loop full of the bacteria and transferring it into the test broth was how the test was done. It was incubated at human body temperature. My bacteria result was negative because it did not change color from red to yellow. A positive-test shows a color change from red to yellow, because the bacteria ferment the sugar into acid, changing the color to yellow and the pH of acidic (pH 6-1). So I started up with an alkaline solution that was not metabolically changed by the bacteria into an acid solution.
Once a pure culture was obtained, I continued with the testing. The citrate test is used to see if the bacteria have the ability to use citrate as a food source. After forty eight hours in the incubator, the media turned a bright blue as it consumed the citric acid. This made the media have an alkaline pH. There were several tests that help make the final identification of the bact... ... middle of paper ... ...erent health hazards.
The bacteria in the... ... middle of paper ... ...colonies for live ampicillin sensitive cells grown on LB Amp100 media with only the buffer. The colonies found on media treated with both the live ampicillin sensitive and heat killed resistant bacteria generated colonies with one exception: The treatment which used DNAse. This treatment showed the same result as the ones without heat killed bacteria: no growth was observed indicating that transformation could not occur without DNA. In conclusion this confirms that DNA is the hereditary medium which can transform bacteria, as discovered by Avery in 1944. References Avery, O. T., MacLeod, C. M. & McCarty, M. (1944).
IDENTIFYING CITROBACTER FREUNDII THROUGH BIOCHEMICAL TESTING. Jebin Jacob November 15th, 14 Naghmeh Hassanzadeh Unknown - 10 Purpose The purpose of this study is to identify an unknown bacterium from a mixed culture, by conducting different biochemical tests. Bacteria are an integral part of our ecosystem. They can be found anywhere and identifying them becomes crucial to understanding their characteristics and their effects on other living things, especially humans. Biochemical testing helps us identify the microorganism present with great accuracy.
There was no change in color of the broth which indicated a negative result. Unknown 3 was also inoculated in a Urease broth, which tested for the presence of Urease, an enzyme responsible for hydrolyzing Urea into ammonia and carbon dioxide. If Urea had metabolized, indicating a positive test, the broth would have turned pink. The test was negative. The figures below provide a summary and supplement the analysis; Figure 1 describes the purpose of the test, the results and its implicatio... ... middle of paper ... ...s culminates in the identification of the organism Micrococcus roseus.
The identification of the bacterial unknown was determined through a series of tests using differential media and a gram stain. These tests revealed information about the motility, the metabolism, and the enzymes of the unknown microorganism. The most basic technique for all tests is called the aseptic technique. This technique is “to prevent contamination of the sample” (Leboffe and Pierce, 2010). This is the first technique taught to students in the lab.
These tests were the EMB test (Eosin Mehylene Blue), the Sulfur Indole Motility (SIM) test, the Urease test, and the Simmon’s Citrate Utilization test. The EMB test checks for a bacteria’s ability to ferment lactose. This test is accomplished by placing the bacteria on Eosin Methylene Blue agar. The agar is selective for gram negative bacteria and those bacteria that can ferment lactose will have colored growth, usually a metallic green sheen. The Sulfur Indole Motility agar tests for three separate characteristics; sulfur reduction, indole production, and motility.