KOH String Test Lab Report

Improved Essays
Introduction: Bacteria are very diverse and are part of the prokaryotic domain. Some bacteria can be harmful, but others can also be beneficial in many ways. There are bacteria everywhere on Earth; places that you would think would have bacteria, like your gastrointestinal tract or our skin (Wenner, 2007). Although bacteria are small in size and are a simple cell organism, it is essential to life. There are different ways in how to distinguish and classify bacteria. One way is you can look at it visually. You can describe if the whole colony is punctiform, circular, rhizoid, irregular, or filamentous. You can describe the edge as entire, undulate, lobate, filamentous, or curled. You can describe the surface as smooth, glistening, rough, …show more content…
It also shows the results from the KOH string test. As you can see all test show that the bacteria is gram-positive. The KOH string test is supposed to determine either the bacteria is classified as gram-positive or gram-negative (Sadava, 2011). We dropped KOH with our bacteria and mixed it. After about a minute, we should have been able to tell if a string has formed or not. We have didn’t have a string form, so we had gram-positive bacteria and a negative string test result. We then did other tests because the string test has a high possibility for false negatives and results can be inconclusive. We swabbed out bacteria on different mediums such as: vancomycin, EMB-lactose, and PEA. There was no growth on vancomycin and EMB-lactose, which makes them gram-positive results. Gram-positive bacteria can’t grow on those two mediums (Leicht, 2015). The EMB-lactose agar has lactose and sucrose for energy. So the sugars are fermentable substrates, which only allow gram-negative bacteria to grow, not gram-positive (Cheeptham, 2014).
Test

Related Documents

  • Improved Essays

    For this experiment, unknown sample #12 was used. The first step in identifying any unknown bacterium is to grow a culture on a nutrient agar plate. This bacterium was also plated on a MAC plate, which is both selective for gram-negative bacteria and differential as well. On the NA plate, bright red colonies were present; on the MAC plate there was bacterial growth as well, but no color change was observed. This lack of color change on the MAC plate indicated that the bacteria did not ferment lactose.…

    • 1060 Words
    • 5 Pages
    Improved 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
  • Improved Essays

    Domestos Lab Report

    • 818 Words
    • 4 Pages

    Bacteria is a type of Prokaryotes and RESEARCH Some Bacteria can be extremely harmful to many animals bodies including humans, these germs attack the immune systems and cause sickness and diseases, these illnesses occasionally result in death. Although not all bacteria are…

    • 818 Words
    • 4 Pages
    Improved Essays
  • Improved Essays

    Unknown 15 Archetype

    • 1308 Words
    • 6 Pages

    If it is examined within 24 hours of plating it will demonstrate alpha-hemolysis, but if examined past 24 hours it will demonstrate gamma-hemolysis (2). Unknown 15 was examined after a one week incubation period, thus, it demonstrated gamma-hemolysis. Mannitol Salt Agar (MSA) was used to distinguish whether Unknown 15 belonged to the genus Enterococcus or Lactococcus. When streak plated onto the MSA medium, Unknown 15 grew on the plate and produced a yellow color change. The growth and color change (indicative of mannitol fermentation) resembled the the positive control Staphylococcus aureus.…

    • 1308 Words
    • 6 Pages
    Improved Essays
  • Improved Essays

    After approval from the professor, the first part of the unknown was to isolate all the gram positive bacteria since the unknown…

    • 1481 Words
    • 6 Pages
    Improved Essays
  • Improved Essays

    Biology Unit 4 Lab Report

    • 543 Words
    • 3 Pages

    -------------------------------------------------------- 5- a-My first answer is: Only with some difficulty and eye strain. (An alternate point of view stated the following: In order to view the nuclei of an elodea cell, the observer would first need to stain the cell according to whether they would like to stain it living or dead. If the observer wishes to see the cells behavior, he would treat it with a dye solution known to not harm the species, and mount it to a microscope slide.…

    • 543 Words
    • 3 Pages
    Improved Essays
  • Great Essays

    M. Luteus Lab Report

    • 715 Words
    • 3 Pages

    Conversely, in Kligler iron agar media, which exams the ability of bacteria to ferment lactose and glucose, M.Luteus gave negative outcome which matches the expected result. Thus, I repeated the Kligler iron agar to test if M.Luteus can ferment glucose and I obtained same result which is negative. Getting positive result for glucose in beginning could be…

    • 715 Words
    • 3 Pages
    Great Essays
  • Improved Essays

    The Mixed Broth culture contained two unknown bacterial cells and they either Gram-negative or Gram-positive. The procedures were followed as stated from the course laboratory manual by Meramec Community College (1). The first step was figuring out the unknowns was to separate the two bacteria. In order to do this, the Trypticase Soy agar was used. The streaking method was used to spread the bacteria across the Trypticase Soy agar to isolate the bacteria.…

    • 1057 Words
    • 5 Pages
    Improved Essays
  • Superior Essays

    Unknown Lab Report

    • 1472 Words
    • 6 Pages

    Using aseptic technique and using the streaking plate method. We also inoculated the unknown sample with the cotton swab onto a TSA slant, in which we transfer the unknown organism to the bottom of the slant and through a zigzag motion to make sure the TSA slant was completely covered with our unknown organism. Once the TSA plate and slant was inoculated with our unknown organism it was allowed to be incubated at 35 degrees Celsius for 24 hours. After the plates had undergone incubation for the full 24 hour duration, color and morphology was observed and noted for our unknown organism. Gram staining was than conducted after, in which we determine if the unknown organisms was either positive or negative based on the thickness of its peptidoglycan wall that was able to retain the crystal violet color or not.…

    • 1472 Words
    • 6 Pages
    Superior Essays
  • Improved Essays

    Unknown Bacteria

    • 1727 Words
    • 7 Pages

    When it derives to contemplating out an unknown bacterial species the whole purpose is to benefit us in order to better understand what this species is capable of. Throughout a general basis of identifying an unknown species we must figure out either it will become a gram-positive or gram-negative type of bacteria and in doing so we must do a gram staining method. This method works because it will direct us to what test we can do next based off either it is negative or positive bacteria, which is exactly what I had done for my unknown. These experiments are not just done without a reason; on the contrary, it is very important to identify these unknown bacterial organisms. For instance, in a medical point of view when becoming very sick to the…

    • 1727 Words
    • 7 Pages
    Improved Essays
  • Great Essays

    Unknown Bacteria Essay

    • 1069 Words
    • 5 Pages

    Motility Test. Due to unknown 10 being gram positive, coccus shaped, and a non-sporeformer many bacteria were eliminated. One test that was run to help in differentiating the bacteria is the motility test. The motility test is preformed by taking soft agar, and heavily inoculating it an inoculating needle. The needle will create a line where the bacteria will diffuse out of it is motile.…

    • 1069 Words
    • 5 Pages
    Great Essays
  • Improved Essays

    Microbiology Lab Report

    • 840 Words
    • 4 Pages

    The two stains, crystal violet and safranin are used to differentiate Gram positive and gram negative cells via their cell walls. Gram Negative cells turn red due to safranin and gram positive remain purple. Through microscopic examination, oil was added onto the 400x magnification. The unknown remained purple…

    • 840 Words
    • 4 Pages
    Improved Essays
  • Improved Essays

    Catalase Test Lab Report

    • 654 Words
    • 3 Pages

    These tests were best use gram negative bacteria to indicated what the unknown microbe is. For the Catalase test, the use of hydrogen preoxide on the sample of the unknown…

    • 654 Words
    • 3 Pages
    Improved Essays
  • Improved Essays

    MacConkey agar, which is media containing crystal violet and bile salts inhibits Gram positive bacteria (5). The media is also differential since the fermentation of lactose is detectable on MacConkey agar by pH indicators. Eosin Methylene Blue agar (EMB) contains chemicals that inhibit Gram positive growth and can identify lactose and sucrose fermentation through the previously described pH detection (3,5). Sometimes, media is developed to identify specific organisms. An example of this is Chromogenic…

    • 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