Lab Report On Gram-Negative Bacteria

The Gram stain was used to determine if the bacteria was gram positive or negative. A negative test shows a pink color and a positive test is a purple color. When a bacterium is negative it is because it has an outer membrane and a thin layer of peptidoglycan that is much harder to stain. A positive bacterium has a thick layer of peptidoglycan and no outer membrane that can be penetrated by crystal violet.

This means that the bacteria for this lawn have cells that are surrounded by a cell wall which includes a thin layer of peptidoglycan and surrounding that is an outer lipid membrane that does not contain the Gram strain. Yet at the same time while Kanamycin was the most effective the Ampicillin and Penicillin had reactions as well. The Ampicillin would kill both Gram-positive and Gram-negative so this could indicate that there are Gram-negative bacteria in the lawn, but the fact that the Penicillin worked as well was what was interesting. This means that this bacterial lawn contains both gram-positive and gram-negative bacteria. Gram-positive are bacteria with cell walls that contain a thick layer of peptiodoglycan that retains the Gram strain. For plate 2, trashcan lid, only the Kanamcyin worked which indicates that the only bacteria in this lawn are Gram-negative, but if that is true why didn't the Ampicillin work at all? Ampicillin works to kill both positive and negative grams, but there was no reaction this time. Could it be that it needs more

The main idea of this experiment was to correctly identify the unknown bacteria, #3. Identification of unknown bacteria yields multiple benefits in many different areas in the research of microorganisms. In this experiment I performed many different test dealing with things such as the presence of enzymes, fermentation abilities and different chemical reactions. Observations made from the tests were then compared to a gram negative unknown chart in order to identify the bacteria. Based off of my results and the chart, I concluded the bacteria #3 was the bacteria Escherichia coli. E. coli is most commonly found in the intestines of warm blooded organisms. Most E. coli strands are non pathogenic however, there are strands

This experiment was given to us to utilized previous knowledge learned throughout the semester to identify a gram negative unknown bacterium. We had to first learn the difference between a gram negative and a gram positive organism. We started off with doing gram stains to determine whether it was positive or negative. Based on the gram stains, a gram positive stains purple and a gram negative stains pink. A gram positive stains purple because the cell walls is made of a thick peptidoglycan layer and doesn’t

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.

All bacterial cells have a cell wall composed of peptidoglycan, However, they can be differentiated into two broad groups, Gram positive and Gram negative. Gram-positive cells have a thick peptidoglycan layer whereas gram-negative cells have a thin peptidoglycan layer. The cell wall of Gram positive bacterial cells also have large amounts teichoic acids, while Gram negative cells do not have any teichoic acids. Graham negative cells have an outer membrane composed of lipids, lipoproteins, and lipopolysaccharide (LPS). Lipopolysaccharide, Also known as endotoxin, is what makes gram-negative bacterial infections so dangerous because it causes symptoms such as shock and a fever. The outer membrane of gram-negative bacteria is more permeable than

Day 2: Agar plates were examined and results recorded. A gram stain was carried out for each of the microorganisms grown and examined under the microscope. The gram stain was able to indicate whether it was a gram negative or positive microbe and with further magnification it was able to indicate the shape (rod or cocci).

In the medical field, certain bacteria need specific antibiotic treatments and to find out what class the bacteria belongs to (whether if it is gram negative or positive) the specimen would have to undergo differential (Gram) staining. Hans Christian Gram was the Danish bacteriologist behind the gram staining technique. His Gram stain technique led to the discovery that Typhus bacillus did not retain the stain. Another procedure like differential staining is called simple staining. The main difference with this procedure is its simplicity and use of just one dye while the differential staining is more complex, uses more staining and helps shows cellular components of the bacteria. There are 3 bacteria that will be in use for the Gram staining.

In gram positive, the cell wall is mostly made up of peptidoglycan; therefore, it stains purple due to the absorption of the primary stain. In gram negative, the cell wall has a thin layer of peptidoglycan and a lipopolysaccharide layer allowing the counter stain to have an effect causing a pink color. To gram stain a bacterium the steps of simple staining are used with a mordant like crystal violet, however it is not dried off until the end of the process. The slide must be rinsed between every step of the gram staining process after crystal violet is used. A mordant is then placed on the slide for one minute to strengthen the color of the stain. Alcohol or acetone is used to decolorize the stain allow it to sit for ten to fifteen seconds. A counterstained is used to add color back to the colorless effect of the decolorizer. The safranin must stay on a slide for one minute before the final rinse, then dried on blotting paper to be seen under a microscope. It can finally be distinguished as a gram positive or gram

Gram staining, also known as Gram's method, is the most important and universally used staining technique in the microbiology and bacteriology laboratory. It is almost always the first test performed in the identification of bacteria (Xu, George).The

Day One: On the first day of our Biochemical Unknown Lab we were given a tube that contained broth media which held two different types of bacterium. Once we were given our broths, we had to streak two Nutrient Agar plates with the mixed culture tube by using a loop. After I streaked my Nutrient Agar plates, I decided to perform a gram stain. First I flamed the loop and set it aside to cool. After I flamed the loop I prepared two slides with a drop of water in the middle. Once the loop was cool I dipped the loop into the broth and smeared the loop onto both slides mixing the unknown bacterium with the water. I flamed my loop, set it aside, heat fixed both slides, and let the slides air dry. Once the slide were dry I set them on two rods above the drainage area and covered the smears with Crystal Violet. I let the Crystal Violet sit on the smear for one minute and rinsed off the Crystal Violet. Once the Crystal Violet was rinsed I applied Grams Iodine and let that sit for one minute. After one minute passed I rinsed the slide again and moved on to applying the alcohol. I dripped the alcohol onto the slide until the

For my gram negative, the first test I did was Phenol red tests (lactose). There was 21 gram negative bacteria and they were divided into two groups: lactose positive and lactose negative. I did the phenol red (lactose) first because it would allowed me to eliminate half of the bacteria. Initially, I got positive lactose fermentation for both of my gram negative. After the Phenol Red test, I did Methyl Red test, followed by Citrate and finally the Indole test. I did these tests in this order because it allowed me to narrow down the bacteria. Both of my gram negative had the exact same results for all of these tests. Both of them was lactose positive, MR positive, Citrate positive and indole negative. It suspicious to have identical results

Gram Positive Bacteria: After picking test tube #2, I inoculated a CNA plate to isolate my Gram positive bacteria. The colistin nalidixic acid in the media inhibits the growth of Gram negative bacteria, the acid affets the outer membrane of the Gram negative so they are unable to reproduce. This test is performed to determine if the Gram positvie bacterium growing on the plate has the ability to break down sheep red bloold cells. After the CNA was incubated in a candle jar, I saw alpha hemolysis, this means incomplete hemolysis. The organism growing on the plate prduced methemoglobulin, leaving a greenish-brownish cloudy zone around the colony. After seeing the results from this test, my bacteria could etiher be Streptococcus pneumoniae or Steptococcus mitis because those are the only ones the show alha

Bacteria can be divided into two types of species, gram positive bacteria and gram negative bacteria. To determine whether a certain type of bacteria was classified tests were conducted by Hans Christian Gram; who discovered the differences within the cell walls of the bacteria. Gram positive bacteria have a thick wall which consists of the protein peptidoglycan. This is opposite to gram negative bacteria which has a thin cell wall, which fold over each other (Wells, 2017). They retain a much thinner peptidoglycan wall between two membranes. The membrane surrounding the cytoplasm and the outer membrane. (Wikipedia, 2017). Both gram positive and gram negative bacteria both stain, gram positive retains violet dye. Gram positive bacteria don't retain the dye and turn red or pink (Diffen, 2017). Due the difference in cell wall thickness gram negative bacteria is harder to inhibit, compared to gram positive bacteria.

Gram stain is the most important and “commonly used differential stain in microbiology” (1). Developed by Hans Christian Gram in 1884, while searching for a way to visualize bacteria in lung tissue of people who had died from pneumonia. Gram used crystal violet as the primary stain, iodine as the mordant followed by treatment with ethanol as a