The Voges-Proskauer test determines if there is acetoin produced by the organism, acetoin if produced by the fermentation of pyruvate. Barritt’s Regent A and B are added to the broth after incubation if there is a positive result then there will be a maroon band at the top of the broth.…
When unknown 32 was tested with the oxidase test, it was found oxidase negative. The catalase test tests for the presence of catalase which breaks down hydrogen peroxide and oxidase dismutase. A small amount of hydrogen peroxide is dropped onto a slide of unknown 32 and resulted in bubbles. This result shows that unknown 32 is catalase positive since it broke down hydrogen peroxide and oxidase dismutase which resulted in water and oxygen. This eliminated Enterococcus spp.…
When you did your hand wash experiment, you decided a variable to test, say, hot vs cold water, you called this variable an “experimental variable” since it was the variable you were testing experimentally. In order to get meaningful data, you need to keep other things the same, for example the washing time had to be the same for both, you called the washing time a _Control_______ variable.…
Alpha will turn green on the plate because the bacterium is outcompeting the body for oxygen because there is an iron binding site. Beta hemolysis is cellular death which means that when it is present in the body it is releasing an acidic byproduct or a basic byproduct which will crush the structure of the blood cells. Alpha outcompetes with the blood for oxygen while beta hemolysis kills the competition for blood. Both result in the bacterium obtaining more oxygen for replication. Yes.…
The purpose of this experiment was to isolate two unknown bacteria and perform a series of selective and differential tests to correctly identify each. After the bacteria was isolated a series of differential and selective tests following the dichotomous key attached were used to identify each bacteria. The Gram-positive bacteria were identified as Staphylococcus aureus with a positive confirmatory test, mannitol salt agar, showing consistent results as well for S. aureus. The Gram-negative bacteria were Pseudomonas aeruginosa with a positive confirmatory…
From the streak plate, several slides were made to determine the morphology of unknown 45. A Gram stain, used to indicate the type of cell wall possessed by the bacterium, was performed. U45 stained a bright pink color and were small ovals and rods in shape. This indicated that U45 was a gram-negative bacillus bacterium. A capsular stain was then performed to determine the presence or absence of a capsule. Unknown 45 was positive for capsules. Having determined that U45 was gram-negative, there was no need to perform the Schaeffer-Fulton endospore stain, which is used detect the presence of endospores in certain gram-positive bacteria.…
On the plate the bacteria produces enzymes called hemolysins these enzymes lyse the red blood cells to certain degrees. Bacteria the fully lyse the blood go through beta-hemolysis. Bacteria that partially lyse the blood go through alpha-hemolysis, and bacteria that doesn’t lyse at all goes through gamma hemolysis.…
In this lab experiment we did several test to determine what our unknown bacteria was. To determine this we recorded the results of how the bacteria reacted to different media. Depending on the results of each test we could narrow down the different bacteria to determine what our unknown is. This experiment will also determine if our bacteria is a fermenter of sugars and if it is catalase positive. If the bacteria is a fermenter they will use the sugars to make ATP. If the bacteria is a fermenter of lactose/sucrose the EMB plate we used will “clearly differentiate between the colonies of lactose fermenting and non-fermenting microbes. In the same medium sucrose was also included to differentiate between coliforms that were able to ferment sucrose more rapidly than those that were unable to ferment sucrose” (Cheeptham & Lal, 2007).…
The oxidase test was performed only on gram (-) bacteria and was used to test for the presence of cytochrome oxidase. Living bacteria were placed on a paper towel and saturated with a chromogenic reducing agent. Within seconds the reagent, acting as an artificial electron acceptor, will turn purple if oxidized cytochrome oxidase is present, indicating a positive test. If no color change is observed, no cytochrome oxidase is present and the test is negative.…
An unknown bacterium experiment, this experiment was done to discover what bacterium was in a mixed culture sample. This experiment worked with enteric bacteria which are members of the Enterobacteriaceae and live in the intestinal tract (Willey et al., 2014). Also found in Willey et al (2014) is some characteristics of enterics such as they all degrade sugars by means of the Embden-Meyerhof pathway, they produce plasmid-encoded proteins and that some of them perform mixed acid fermentation, some use enzyme systems like formate dehydrogenase and pyruvate formate-lyase (PFL) The first thing that had to be done was the streak plating to isolate the bacterium, then the next lab multiple tests were ran to help identify which bacterium was in the sample. One of the most important tests done was gram staining because it helped to limit the possible bacterium that it could have been. To be sure which bacterium was worked with we referred to the Bergey’s manual and compared the results to the possible bacterium.…
The change from negative serum, without antibodies specific to an infecting agent, to positive serum, containing antibodies against that infecting agent, is called…
Many different species of bacteria look similar under the microscope and also have the same staining results (ex. Gram stain). To be able to differentiate between the different species, one can look at the metabolic differences (fermentation), as well as the environmental condition differences (temperature, pH, oxygen requirements). Being able to manipulate these conditions in a controlled environment can help to correctly identify the exact bacteria. Different media can be used to culture and identify bacteria.…
Having the ability to collect and identify unknown microorganisms is vital in health and medicine. This capability is important for a variety of reasons, such as knowing the causative agent of disease, knowing if the microorganism obtains any beneficial properties and knowing the correct microorganism to use to create a successful antibiotic. Implementing the experimental methods learned thus far in the microbiology laboratory allowed an unknown bacterium to be identified as a result of this study. This study allows the student to exercise their ability to use and understand sterile techniques, transmission, and prevention of microorganisms.…
As I recall from earlier that semester, the first test that needed to be performed was the Gram stain. The Gram stain is a staining technique that aids in distinguishing cell wall characteristics and the cellular morphology. Bacteria will stain Gram positive, which is a purple color, or Gram negative, which is a pink color. Also, the Gram stain can help to identify the shape of the bacterium. The three basic shapes are cocci, bacilli and spirilli, which means that cocci are berry shaped, bacilli are rod shaped and spirilli are spiral shaped. My unknown bacteria stained purple which means that it is Gram-positive and was berry shaped meaning that the bacterium is cocci. These results have led me to the next step for me to master, the catalase test.…
4. The goal of the direct fluorescent antibody test is to test for the presence of…