It is important in microbiology to be able to identify an unknown microorganism. Many tests that characterize functions of bacteria have been developed to accomplish this task. The unknown bacterium that was tested was discovered to be Escherichia coli. E. coli is a Gram-negative, bacillus bacterium. Gram-negative means there is an outer membrane surrounding the thin peptidoglycan layer of the cell. Bacillus means that the bacterium is rod-shaped. The E. coli was identified as Gram-negative and bacilli from performing a Gram stain. A Gram stain uses crystal violet for the primary dye and safranin as a counter stain (1). Gram-positive bacteria have a very thick peptidoglycan layer in their cell wall. This thick cell wall will stay stained purple by the crystal violet-iodine complex, and Gram-negative bacteria will be decolorized and stained pink from the safranin counter stain (1). The peptidoglycan layer’s thickness determines whether it is stained pink or purple.
To test an organism’s ability to use citrate as a source of carbon, a citrate utilization test is. This test is ...
... middle of paper ...
...n dioxide. The ammonia would cause the broth’s pH to be alkaline, which would turn the broth bright pink (3). Since the broth stayed the same orange/yellow color, we know that the urea in the broth was not degraded to ammonia, meaning that the organism does not produce the enzyme urease.
1) Bartholomew, J.W., and T. Mittwer. 1952. The Gram stain. Microbiology and molecular biology reviews. 16: 1-29.
2) Krajewska, B. 2009. Ureases I. Functional, catalytic and kinetic properties: A review. Journal of Molecular Catalysis B: Enzymatic. 59: 9-21.
3) Roberts, G.D., C.D. Horstmeier, G.A. Land and J.H. Foxworth. 1978. Rapid urea broth test for yeasts. Journal of Clinical Microbiology. 7: 584-588.
4) Vaughn, R.H., J.T. Osborne, G.T. Wedding and J. Tabachnick. 1950. The utilization of citrate by Escherichia coli. Journal of Bacteriology. 60: 119-127.
Need Writing Help?
Get feedback on grammar, clarity, concision and logic instantly.Check your paper »
- Throughout the majority of the semester, my partner Kathryn and I, have performed numerous tests to identify our unknown species. After a series of results, we identified are unknown as Escherichia coli, which is also known as E. coli. One of the first experiments we sought out to determine for the characteristics of Escherichia coli was the Gram stain test. In this test, we determined that the Gram stain was negative, due to the fact that after using the counterstain Safranin, the stain still displayed a pinkish hue.... [tags: Bacteria, Escherichia coli, Gram staining]
1253 words (3.6 pages)
- ABSTRACT: Water samples from local ponds and lakes and snow runoff were collected and tested for coliform as well as Escherichia coli. Humans as well as animals come into contact with these areas, some are used for recreational activities such as swimming and some are a source of drinking water for both animals and humans The main goal of this experiment was to see which lakes, snow run off and ponds tested positive for coliform or Escherichia coli and to come up with some reasoning as to why. It was found that the more remote pond with less contact contained the most Escherichia coli.... [tags: Escherichia coli, Bacteria, Water pollution, Lake]
1024 words (2.9 pages)
- In class we was given the task of identifying unknown broth cultures, I received number 69. I went through several tests to figure out what bacterium I received. First I created a slide of the broth by putting a small amount of the broth on the slide and letting it dry for ten minutes. Next I stained the slide by applying the reagents; crystal violet, grams iodine, decolorizer and safranin. From that I discovered that this bacterium was gram-negative, this would determine the next couple of tests I would do to identify my unknown bacterium.... [tags: Escherichia coli, Bacteria]
1094 words (3.1 pages)
- The overall objective of this report was to document a series of experiments conducted on an unknown bacterium in order to properly identify unknown bacterium 115. Throughout all tests, proper aseptic technique utilized in order to transfer cultures of the unknown bacterium. Such techniques refers to fundamental procedures conducted in sterile conditions in order to prevent cross-contaminating of the culture, medium, or surroundings. (1) Several commonly aseptic transfer techniques include: organization, holding the inoculating loop/needle with one’s dominant hand as if it was pencil, and utilizing a test tube rack.... [tags: Bacteria, Escherichia coli]
1335 words (3.8 pages)
- Clostridium difficile, formally named Bacillus difficilis, due to how difficult it was to isolate and cultivate was first isolated from newborn infants in 1935. (Hall and O’Toole, 1935). It was not until 1970, that a relationship was formed between C. difficile and humans with colitis (Ehrich et al., 1984). In 1984, was the first time C. difficile was identified in mature horses, located in the Potomac River area, with diarrhea. Cases of C. difficile colitis in horses treated with antimicrobials increased in 1993.... [tags: Bacteria, Escherichia coli, Gut flora]
1021 words (2.9 pages)
- During a lab in my Microbiology class, we got the chance to do what is called an Unknown Report. It is a report of an unknown sample of bacterial that we performed different tests on to identify the bacterial species. By following the important steps of aseptic technique in all tests, we were able to identify the unknown bacteria. These tests involved different petri dish agars, broths, and slants to know what kind of bacteria we had. As a result, we identified our bacteria as an Escherichia coli.... [tags: Escherichia coli, Bacteria, Gram staining]
1226 words (3.5 pages)
- Microbiology is the biological study of organisms that are too small to be seen with the naked eye (1). Microbiology includes examining a variety of different microbes such as bacteria, archaea, protozoa, fungi and viruses (1). By examining these microbes, their relationship with people and the environment they grow in, is better understood. These examinations of microbes have played a major role in comprehending how microbes can be helpful and harmful, and how they should best be dealt with. With new and emerging discoveries in microbiology, medical treatments have expanded.... [tags: Bacteria, Escherichia coli]
1787 words (5.1 pages)
- How We Know DNA is Hereditary Ever since taking biology, every child knew that DNA is hereditary, meaning that the offspring’s DNA is a sum of their parents’ DNA. But how do we know that is true. There have been multiple experiments performed within the last century that prove or lead up to the fact that DNA is hereditary material. Early genetic testing started when Frederick Griffith’s experiment on the significance of Pneumococcal types was published in 1928. In this series of experiments he researched pneumonia in attempt to develop a vaccine.... [tags: DNA, Genetics, Bacteria, Escherichia coli]
1280 words (3.7 pages)
- TESTING ANTIMICROBIALS TO FIND OUT MOST EFFICIENT AGAINST ESCHERICHIA COLI Ana Shafer 1. INTRODUCTION Fighting against germs and microbes that may harm us is a never ending battle. Humans have so many ways to disinfect our bodies, our mouths and even our surroundings. Finding an antimicrobial that will rid us and the world around us of microbes that will harm us is nearly impossible. It is a common fact that there is nothing in this world that will kill 100% of germs. Escherichia coli is bacteria that lives in human and animal’s intestines.... [tags: Bacteria, Escherichia coli, Antiseptic]
1051 words (3 pages)
- Escherichia coli (E. coli) is a member of the Enterobacteriaceae family of organisms. It is a non-spore forming, facultative anaerobic, gram negative rod capable of growing on a variety of media and, similar to other members of the Enterobacteriaceae family, contains the enterobacterial common antigen. Most E. coli are part of the normal flora of the human gastrointestinal tract, however some strains are pathogenic and capable of causing clinical disease. Epidemiologic classification of E. coli is based on the expression of certain surface antigens.... [tags: Escherichia coli, Bacteria]
1293 words (3.7 pages)