Gram, Gram And C. Gram

The colonies were smooth, translucent, and had a white brownish color. The Gram stain resulted in Gram positive cocci. After the Gram stain was completed, the bacteria were streaked on a Mannitol-Salt Agar plate and a Catalase test was performed. After these test were completed a Phenol Red Dextrose Fermentation tube was inoculated, and a SIM Tube inoculated.

The next step of the project included preparing a Gram stain to discover the cell shape, arrangement, and if the bacteria is gram positive or

2) Record the shape of the bacteria, the arrangement of the bacteria, and the gram staining characteristics.

The drops of crystal violets, approximately 15 drops, were flooded until the smear were all covered and then allowing resting for one to two minutes. After two minutes, the slide was titled over the sink and washed off, with the distilled water bottle, by aiming the stream of water above the smear. The specimen appeared blue-violet when observed with the naked eye. The drops of Gram’s iodine were applied on the slide until covered and then allowed to react for one minute or more. After the time elapsed, the slide was rinsed again with distilled water following immediate drops of Gram stain decolorizer added one drop at a time.

The purpose of this lab was to identify an unknown microorganism using lab techniques. The importance of identifying microorganisms is essential to the survival of humans, expansion of modern day medicine and improvement of quality of life. In 1884, Hans Christian Gram designed a differential staining technique to identify bacteria that would change the future of microbiology. He give rise to a staining process, known as the Gram stain to differentiate microorganisms into two groups between positive and negative gram staining microorganisms. The Gram stain is essential in a lab technique as it distinguishes the cells based on the physical properties of the individual cell walls, and is almost always the first test preformed to differentiate a microorganism. The identification of weather a microorganism is gram positive or negative can revel the bacteria’s virulence, cell wall structure, resistance to antibiotics, resistance to physical disruptions and so much more. In order to identify the unknown provided, unknown #27, the Gram stain was the first test preformed. After discovering that the unknown bacterium was indefinitely a gram positive microorganism, the vast possibilities were narrowed down. However, In order to more definitively identify the unknown, the next step was to preform biochemical tests. A biochemical test identifies metabolic

8. Discuss a possible mechanism of Gram Staining in terms of differences in structure and chemistry between the walls of gram-positive and gram-negative

The purpose of this experiment is to distinguish and indentify an unknown bacterium. There are several tests that can help one eliminate and narrow down the options. The most useful test, and the very first one done, is a gram stain. This test will tell whether the bacterium is gram-positive or gram-negative. After the type of gram stain is identified, the tester has a wide array of differentiating tests at their disposal. Based on the results from these tests, and the numerous others that are available, one can accurately establish the identity of an unknown bacterium.

Crystal violet stains the cell of the bacteria and is placed over the heat fixed slide for one minute then rinsed with H2O. The mordant that binds the stain is gram’s iodine and is recommended to be present on the slide for one minute. Alcohol is used as the decolorizer and is dripped over the recently rinsed slide until the slide runs slightly blue. If the bacterium retains the crystal violet it is due to the thicker peptidoglycan in the cell wall (gram-positive). The bacteria will then be stained with the counterstain safranin for 45 seconds. When crystal violet is not retained in the cell wall of the bacterium it will stain pink (gram-negative). A gram stain was immediately performed with the recently inoculated streak plate. An inoculating loop was used to gather some of the bacteria from an isolated colony. The loop was placed on a new slide and the transferred bacterium to the slide. The slide was dried, heat-fixed, and the gram stain process just described was completed. After microscopic analysis, it was determined the first unknown bacteria was a gram-positive cocci. The second unknown was determined to be gram-negative cocci. With this information a set group of test decided and performed based on the Unknown Bacteria Flow Chart as provided in the lab manual (Pg.) these test and the results are shown in record on the following pages. These are separated for the gram positive and the gram negative

The unknown plate acted as the stock master plate, and was used to aseptically streak the unknown for isolation and was incubated at 37°C for 24 hours. After the incubation, a Gram stain was performed. Using an inoculating loop, a drop of DI water was placed on a clean slide, and a sample of bacteria was aseptically transferred and mixed in the DI water. The slide air dried for a couple of minutes, and was then heat fixed to keep the bacteria on the slide. Using a staining tray to hold the slide, 2 drops of crystal violet dye was placed on the dried bacteria and allowed to sit for 2 minutes (2). After the CV was set, DI water was used to rinse off any remaining dye. The smear was covered in Gram’s iodine for 1 minute. After a minute the iodine was rinsed off and the slide was tipped to the side to allow 2-3 drops of ethanol decolorizer to remove any remaining purple coloring. The slide was rinsed again, and the smear was covered with safranin for 30 seconds. After 30 seconds the slide was rinsed off and blotted dry with bibulous paper (2). The smear was then observed under a microscope to determine gram nature and

I performed a gram stain on my unknown 7. It appeared to be purple and round shaped. I came to the conclusion that my bacterium is gram-positive, cocci. A gram stain is a differential test. It allows recognizing the difference between two cell walls structures. In a gram-positive cell wall contains a thick peptidoglycan layer covering the plasma membrane (2). The purple staining is retained around the cell

Figure #1 This picture show the gram stain of unknown #3. The image is under 1000x magnification using oil immersion technique. Gram (-)

Bacteria are identified systematically by using various different techniques and narrow down their species present in an unknown bacterial culture. This is highly usefully in identifying infections correctly and in research regarding microorganism. Laboratories use identification techniques based on primary characteristics and gram stains to carefully identify unknown organism in samples collected (faeces, blood, sputum, mucosal swabs), to determine the cause of infection and define a disease.

From last week’s test, we achieved pure cultural characteristics from the two slants we made. The growth we saw on the agar slant that contained the yellow specimen was a soft, smooth, yellow growth. The growth we saw on the beige specimen was a thin, even, beige growth. Both cultural characteristics were achieved in the appropriate categories. The categories we were looking for contained abundance of growth, pigmentation, optical characteristics, and consistency. Today we will be preparing two bacterial smears from each specimen and Gram staining them. The reason we are conducting this test is to differentiate between two principle groups, gram positive and gram negative and to further know if a pure culture from both organisms was achieved. This is important for classification and differentiation of microorganisms. The Gram stain reaction will help us tell the difference of the chemical composition of bacterial cell walls. The Gram stain procedure uses four different reagents such as crystal violet, gram’s iodine, ethyl alcohol, and safranin. Before the Gram stain is performed we must make two bacterial smears of the two specimens. We placed one loop of distilled water on a clean slide aseptically. He transferred the specimen from the agar slant that contained the yellow growth and placed it on the slide with the water and gently mixed it together in a circular motion approximately the size of a nickel. He let the smear air dry for one minute and gently heat

The purpose of the Gram Stain test was to identify the morphology and gram nature of the unknown bacteria (Delfiner, Martinez, & Pavia, 2016). First, a mixed smear from the unknown bacterium was placed on a microscope slide. Once the mixed smear had air dried it was then heat fixed to adhere the bacterial cells to the slide. After the heat fixation, a series of stains/solutions were added to complete the Gram stain test. The series of stains/solutions included Crystal violet (1min), Iodine (1min), ethanol (2-3 drops), and Safranin (30 sec). Also, after the addition of the Crystal violet and Safranin, DI water was used to remove the stains. Lastly, bibulous paper was used to blot dry the microscope slide and the slide was placed under the microscope. To clearly identify the morphology and gram nature of the unknown, a drop of oil immersion was placed on the slide to utilize the oil immersion

Most bacteria are classified as either gram positive or gram negative. Gram positive is a purple stain and gram negative will appear pink or red. Gram negative can cause many kinds of infections. One type of bacteria is Escherichia which is a rod shaped bacteria. A Gram stain is used in lab setting to identify what type of bacteria is present. A sample is placed in a nutrient media and incubated. This media will encourage bacteria growth present. This process allows for further testing and to identify what kind of bacteria is present to allow for appropriate treatment.