Gram Unknown Lab Report

Improved Essays
In order to determine the identity of two unknown bacteria, I performed a series of experiments over several days. To begin this process I created a dichotomous key that I utilized as a guide to perform a series of inoculations, while using both selective, and differential media. The series of inoculations eliminated bacterium based on test results until the correct bacteria were both positively identified. On day one of this process I received two bacteria, one labeled 7A and the other labeled 7B. I began the experiment with thirteen possible bacteria. The thirteen possible bacteria included, Enterococcus faecalis, Bacillus subtilis, Bacillus megaterium, Staphylococcus aureus, Staphylococcus epidermis, Micrococcus roseus, Micrococcus luteus, …show more content…
In order to determine this I performed a gram stain on each of the bacteria. I observed each bacterial slide on a microscope under 1000X resolution. The bacterium labeled 7A showed multiple staphylococcus arrangements that were stained red. I determined that this bacterium was gram negative because of red color of the bacteria. The bacterium labeled 7B showed multiple single bacilli that were stained purple. I determined that this bacterium was gram positive because of the purple color of the bacteria. By performing the gram stain, I was able to divide my two bacterium into 1 gram positive bacterium, and 1 gram negative bacterium. I was now able to determine that bacterium 7A could only be one of the gram positive bacteria. The gram positive bacteria where E. faecalis, B. subtilis, B. megaterium, S. aureus, S. epidermis, M. roseus, and M. luteus. Additionally, I was also able to reduce the possible bacteria for 7B to one of the gram negative bacteria. The gram negative bacteria included, P. vulgaris, E. coli, C. freundii, E. aerogenes, A. faecalis, and P. …show more content…
I performed this inoculation in order to identify whether the unknown bacterium was able to ferment the carbohydrate Mannitol. After 48 hours of incubation, the result of bacterium 7A was positive for Mannitol fermentation. I was now able to determine that bacterium 7A could only be a bacteria that would test positive for Mannitol fermentation. The possible bacteria were then reduced to E. faecalis, B. subtilis, B.megaterium, and S. aureus. With this result I was also able to eliminate S. epidermis, M. roseus, and M. luteus. Additionally on day one, I inoculated bacteria 7B onto a Urea tube of media in order to further eliminate incorrect bacteria. The Urea tube would distinguish if bacterium 7B would produce Urease, resulting in a positive test result. After 48 hours of incubation, the result of the Urea agar slant was positive. This result reduced my possible bacterium’s identity to bacteria that would produce a positive result in a Urea agar slant. The possible bacteria were P. vulgaris, C. freundii, or P. aeruginosa. I was then able to completely rule out E. coli, E. aerogenes, and A. faecalis as possible

Related Documents

  • Improved Essays

    A Gram stain was then performed to confirm that bacteria #12 was indeed gram-negative and also showed that it was rod shaped. Following the provided flowchart, the oxidase test was then performed in order to test for the enzyme cytochrome oxidase; unknown bacteria #12 tested negative. Finally, the bacterium was grown on an EMB plate, which resulted in no color change; this indicated again that the bacteria did not ferment lactose. After these tests were completed, the results were compared to the provided identification flowchart.…

    • 1060 Words
    • 5 Pages
    Improved Essays
  • Improved Essays

    Hesi Case Study Mariana

    • 1065 Words
    • 5 Pages

    Additionally, Mariana’s faeces sample result were clear of any bacteria growth especially Salmonella and E.coli. Several species of microorganism such as…

    • 1065 Words
    • 5 Pages
    Improved Essays
  • Improved Essays

    After, then other biochemical tests were performed that were specific to the gram- negative bacteria to start the identification process of the unknown. The results of the gram negative tests lead to the identification of the bacteria Alcaligenes faecalis. The gram stain procedure was the first test performed by isolating a colony from the pure culture streak plate. The gram stain was followed orderly right from the referenced laboratory manual. The test resulted to be Gram- Negative bacteria from the compound microscope which were pink and rod shaped that can be seen with the 100x objective lens with the oil immersion.…

    • 1481 Words
    • 6 Pages
    Improved Essays
  • Great Essays

    Unknown Lab Report

    • 1689 Words
    • 7 Pages

    Since MacConkey agar is selective for gram-negative bacteria (1), I was able to compare the growths on this plate (Figure 2) to those on the blood agar plate (Figure 1) and matched the colorless, flat, circular, undulate colonies on the MAC plate with the very light gray, irregular, flat, undulate colonies on the blood agar plate and identified them as the gram negative isolate. Due to the disappearance of my MAC plate, I had to isolate the Gram negative bacteria from the blood agar plate. Since there were matching colonies on the blood and MAC plates, I was able to identify the gram negative colonies from the gram positive growths and create a gram stain to confirm this identity. The result of the gram stain, shown in Figure 3, consisted solely of pink bacteria, which confirmed this was the gram negative isolate in accordance with Hans Christian Gram, the developer of the gram stain, who stated pink bacteria were gram negative (2). Since there was only one type of bacteria present on the gram stain slide, I confirmed that the sample was uncontaminated and used the colonies to make a stock culture (Figure 4).…

    • 1689 Words
    • 7 Pages
    Great Essays
  • Superior Essays

    Gram Negative Unknown Lab Report #20 BIOL 3444-008 Giang Nguyen TA: Malini Kotak 11/05/2014 Abstract The experiment is conducted in order to identify a randomly given unknown gram-negative microorganism. By comparative analysis of biochemical tests that were performed throughout the semester to find out its characteristics and determine the identification of bacterium out of four potential unknown was given. To figure out the characteristics, T-streak was performed to isolate the sample from broth to a Tryptic Soy Agar plate, along with an additional slant in case something wrong with the original plate that can possibly affect the result.…

    • 1514 Words
    • 7 Pages
    Superior Essays
  • Great Essays

    Unknown Lab Report

    • 2913 Words
    • 12 Pages

    The Identification of Two Unknown Bacteria Mixtures Through the Method of Characteristic Testing and Elimination Khoa Vuong TA: Charlie Roll Micro 3301 4/11/24. Abstract: There is a surplus amount of microorganisms that are out there in the world. A single swab of any surface, including the human body, will yield many different types of microorganisms. Once grown on a nutrient-rich medium, the identification of these microorganisms can be made by isolating pure colonies and performing and using various plates and broth and recording its characteristics.…

    • 2913 Words
    • 12 Pages
    Great Essays
  • Improved Essays

    Microbiology Lab Report

    • 840 Words
    • 4 Pages

    To determine the unknown’s morphology is the first step in narrowing down possible organisms. A MacConkey and Mannitol Salt Agar tests were conducted on the organism and revealed the following. No growth on the MacConkey plate resulting in a gram positive bacteria and the Mannitol Salt Agar result showed it could be Staphylococcus or Micrococcus. (1) A gram stain test was used in determining the shape, size and arrangement of the unknown bacteria (1). The unknown organism is heat fixed onto the slide, in order for the organism to be stained.…

    • 840 Words
    • 4 Pages
    Improved Essays
  • Improved Essays

    Unknown Lab Report Essay

    • 808 Words
    • 4 Pages

    The goal of this experiment was to identify as well as learn about an unknown species of bacteria along with learning some techniques when it comes to process of elimination in a scientific study. To do this, many different tests were completed to help rule out species that were provided on a sheet of paper listing the possible candidates for the unknown microbe. The Bergey’s Manual of Determinative Bacteriology flow chart was also used to narrow down choices as tests were completed, along with a flowsheet of gram positive and negative microbes provided in Microbiology Class. To begin the process of identifying unknown microbe #7, two isolation streaks of the mystery microbe were made in order to determine whether the microbe likes to grow at 30˚C or 37˚C. It was discovered that the microbe likes to grow more at 37˚C. Next, an observation under the microscope as well as a gram stain were conducted. These tests were conducted in order to identify and understand the shape of the microbe and if it was gram…

    • 808 Words
    • 4 Pages
    Improved Essays
  • Improved Essays

    The first step was to streak the bacterium with a sterilized look onto a Mueller Hinten plate. The MH plate was incubated at 37 degrees Celsius for 48 hours. Upon return and observation, the MH plate did not isolate the colony enough to be able to test the bacterium. The professor then handed an alternate 10 that was a pure culture to streak. It was with a sterilized loop that some of the pure culture was taken out and gram stained as directed by the laboratory manual (1).…

    • 1057 Words
    • 5 Pages
    Improved Essays
  • Improved Essays

    This ultimately helped us decide that our organism was Enterobacter Aerogenes. Out of the microorganism in our chart our unknown results matched with the results that were associated with this bacteria the…

    • 1097 Words
    • 5 Pages
    Improved Essays
  • Great Essays

    Unknown Bacteria Essay

    • 1069 Words
    • 5 Pages

    Introduction Identifying unknown bacterium is not only vital to microbiology, but also to the medical and pharmaceutical industries in order to treat disease/infection properly. Bacteria are classified and identified to distinguish among strains and to group them by criteria of interest (1). There are several different procedures that can be utilized to identify a bacterium. This includes the oxidation test, gram stain, and catalase test. The purpose of this lab report is to show the understanding of all procedures used to identify the bacterium, and explain how the given results led to the identification of the unknown bacterium.…

    • 1069 Words
    • 5 Pages
    Great Essays
  • Improved Essays

    The methods that have been taught for identifying a bacteria have been applied to determine the unknown bacterial growth. The first procedure performed was obtaining a culture from the NA plate, Section 2 “Handwashing Ex99”, which had previously been incubated…

    • 254 Words
    • 2 Pages
    Improved Essays
  • Improved Essays

    Bacterial Unknowns

    • 789 Words
    • 4 Pages

    Which seven of those bacteria are gram positive bacteria, and the other six are gram negative. My first step in the…

    • 789 Words
    • 4 Pages
    Improved Essays
  • Improved Essays

    The properties of selective and differential media suggest that differences between the bacterial species could be used in this lab to identify these six species but their effectiveness is unknown. The efficacy of identifying a completely unidentified bacterium in a cost-sensitive manner using these test also has yet to be determined. We hypothesized that applying a combination of selective and differential media with biochemical tests would provide a presumptive identification of the first group of six unknown bacteria. We also hypothesized the identification an unknown member of the Enterobacteriaceae family referred to as unknown #53 could be definitively identified using the API 20E and other tests. To test the first hypothesis, samples of four of the six unknown bacteria were streaked onto plates of Mannitol Salt agar, MacConkey agar, and Eosin Methylene Blue agar to examine their growth on the media.…

    • 1018 Words
    • 4 Pages
    Improved Essays
  • Improved Essays

    Gram Staining Lab Report

    • 1611 Words
    • 6 Pages

    Introduction In this lab report I use two different techniques to identify Unknown A and Unknown B bacteria’s. These techniques are gram staining and metabolic testing. I first used Gram staining to distinguished and identify the bacteria’s. Han Christian discovered gram staining in 1882, he had biopsy a patient lung that had pneumonia.…

    • 1611 Words
    • 6 Pages
    Improved Essays