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Gram staining practical
Importance of gram staining technique
Gram staining practical
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Most of the results from the science experiments conducted did not occur like they were expected. Most of the results were false negative or false positive due to a human error within preparation of the bacteria slides. For example, the simple stain results for the Corynebacterium xerosis bacteria were inconclusive because they appeared to be very tiny circular dots instead of their usual rod shape. There is a possibility that it could have been the result of overheating the bacteria during the heat fixing process. This also could have been the result of leaving the crystal violet dye on for too long allowing the dye to dry up on the slide. The next example of an experiment’s results gone wrong is apparent in the Gram staining experiment. The
I identified the genus and species of an unknown bacterial culture, #16, and I applied the following knowledge of morphologic, cultural and metabolic characteristics of the unknown microorganism according to the laboratory manual as well as my class notes and power point print outs. I was given an incubated agar slant labeled #16 and a rack of different tests to either examine or perform myself; the tests are as follows: Gram Stain; Nutrient Gelatin Test; Carbohydrate Fermentation; Dextrose, Lactose and Sucrose; IMVIC tests; Citrate, Indole, Mythel-Red and Vogues Proskauer test; as well as a Urease and TSI Test. Materials and Methods/Results Upon receiving the Microorganism (M.O.) #16, I prepared a slide by cleaning and drying it. Then, using a bottle of water I placed a sterile drop of water on the slide and used an inoculating loop, flame sterilized, I took a small sample of the unknown growth in my agar slant and smeared it onto the slide in a dime sized circle and then heat fixed it for ten minutes.
Each test that was used in the lab for the unknown bacteria had been performed on many different bacteria and shown that each test has different results depending on the bacteria given. The first test, the Gram stain, confirmed that the unknown bacterium was a gram negative bacilli. After performing the remainder of the tests and comparing them to the twelve negative bacteria that it could be out of it was basically a process of elimination. Basically looking at all the results and seeing which tests separated positive verses negative results the most. After reviewing all of the tests the first test that stuck out besides the gram stain was the lactose fermentation, followed by the citrate utilization test and then by the indole test. The lactose fermentation test eliminated seven of the 12 bacteria. From the five bacteria left the citrate utilization test eliminated who more of the bacteria, and last the indole test eliminated two of the three bacteria left leaving only one bacterium left. After comparing the results to the results of the 12 tests and separating which tests were positive and negative for each it was obvious that the bacteria had to be Shigella
In this lab project, the microbiology students were given 2 unknown bacteria in a mixed broth each broth being numbered. The goal of this project is to determine the species of bacteria in the broth. They had to separate and isolate the bacteria from the mixed broth and ran numerous tests to identify the unknown bacteria. The significance of identifying an unknown bacteria is in a clinical setting. Determining the exact bacteria in order to prescribe the right treatment for the patient. This project is significant for a microbiology students because it gives necessary skills to them for future careers relating to clinical and research work.
IDENTIFYING CITROBACTER FREUNDII THROUGH BIOCHEMICAL TESTING. Jebin Jacob November 15th, 14 Naghmeh Hassanzadeh Unknown - 10 Purpose The purpose of this study is to identify an unknown bacterium from a mixed culture, by conducting different biochemical tests. Bacteria are an integral part of our ecosystem.
Possible errors include leaving in the test strips for too long, draining too much water into the aquatic chamber (overfilling/watering), and inverting the tubes for a shorter amount of time than required. Although there are many possible human errors that could be committed in this lab, it is important to note that the tools used for water testing could be expired and could therefore not work as well at detecting the proper levels for dissolved oxygen, pH, and nitrate.
ABSTRACT: Water samples from local ponds and lakes and snow runoff were collected and tested for coliform as well as Escherichia coli. Humans as well as animals come into contact with these areas, some are used for recreational activities such as swimming and some are a source of drinking water for both animals and humans The main goal of this experiment was to see which lakes, snow run off and ponds tested positive for coliform or Escherichia coli and to come up with some reasoning as to why. It was found that the more remote pond with less contact contained the most Escherichia coli. However, another lake that many swim in and use as their drinking water indeed tested positive for a small amount of Escherichia coli. The two samples from the snow showed negative results for both coliform and Escherichia coli and the two more public ponds that aren’t as commonly used as a source of human drinking water but animal drinking water tested in the higher range for coliforms but in the little to no Escherichia coli range. It was concluded that the remote pond should be avoided as it’s not a safe source of drinking water for humans or animals. Other than that, the the other ponds are likely to be safe from Escherichia coli, but coliforms are a risk factor.
I also inoculated a tryptic soy broth (TSB), a nutrient gelatin deep, a motility agar deep, a fluid thioglycollate medium (FTM) tube, and a TSA plate with my unknown culture. All of these inoculated media were incubated until the next class period (about 48 hours). Then when I came to class most of my inoculated tubes and my streak plate appeared to have growth. The next step I took was making a gram stain to determine the gram reaction and cellular morphology of my unknown. I used my working slant to do this, after careful examination of the gram stain, I learned that my unknown was a gram-positive bacterium. I then preceded by making a negative stain to see the size of the cells of my unknown bacteria. The cell shape was cocci and the cells occurred in clusters of tetrads. After discovering that my unknown bacteria was gram-positive cocci, I turned to page 207 of the lab manual to narrow down my options, there was only four out of the gram-positive list that were
In the last decade, the number of prescriptions for antibiotics has increases. Even though, antibiotics are helpful, an excess amount of antibiotics can be dangerous. Quite often antibiotics are wrongly prescribed to cure viruses when they are meant to target bacteria. Antibiotics are a type of medicine that is prone to kill microorganisms, or bacteria. By examining the PBS documentary Hunting the Nightmare Bacteria and the article “U.S. government taps GlaxoSmithKline for New Antibiotics” by Ben Hirschler as well as a few other articles can help depict the problem that is of doctors prescribing antibiotics wrongly or excessively, which can led to becoming harmful to the body.
An understanding of the scientific method is important in the microbiology laboratory. The scientific method is known in the microbiology world to be the steps that are followed by scientists to answer specific questions about the world. Scientists who work in laboratories especially a microbiology laboratory use the scientific method. The purpose of the scientific method is to construct an accurate, reliable, consistent representation of the world. The scientific method involves steps such as asking a question, doing background research, constructing a hypothesis, testing your hypothesis by doing an experiment, analyzing your data and drawing a conclusion, and reporting your results. Using the scientific method is to clearly do an experiment
One of the human errors in the lab was the group was destaining the gel in the sink to rapidly and the gel broke in half cutting off some of the important data. This error could simply be fixed by being more gentle with the data. Also, during the begging of the lab while filling the wells with gel the group did not put the same amount in each. This error could be fixed by simply taking time filling the wells and making sure no more gel is in the micropippette before moving on to the next well. Finally, another human error consisted of the power source getting shut off when our gel was not in it for a total of 20 minutes. The error could be fixed by getting more outlets in the room so the power so the power source was not shut off to early. The major experimental error was the groups were not able to fully distain the gel since the class was over after short amount of time. To fix this experimental error starting the lab sooner and planning more efficiently would allow for enough time to distain the gel. In addition, the buffer after used for one experiment was placed back into the original bottle and used for multiple other experiment what if the buffer had been overused and tampered other experiments would get inconclusive results. An easy way to fix this experimental error is getting little bottles of buffer and throwing them away each time rather then using the same one each time. Thus, if these experimental and human errors were fixed then the outcomes would be more accurate and the interpretation of the data would be
Describe the experiment. What is the most important thing you learned from this experiment? Provide an example (from the experiment to explain your answer).
Bacterial cells, like plant cells, are surrounded by a cell wall. However, bacterial cell walls are made up of polysaccharide chains linked to amino acids, while plant cell walls are made up of cellulose, which contains no amino acids. Many bacteria secrete a slimy capsule around the outside of the cell wall. The capsule provides additional protection for the cell. Many of the bacteria that cause diseases in animals are surrounded by a capsule. The capsule prevents the white blood cells and antibodies from destroying the invading bacterium. Inside the capsule and the cell wall is the cell membrane. In aerobic bacteria, the reactions of cellular respiration take place on fingerlike infoldings of the cell membrane. Ribosomes are scattered throughout the cytoplasm, and the DNA is generally found in the center of the cell. Many bacilli and spirilla have flagella, which are used for locomotion in water. A few types of bacteria that lack flagella move by gliding on a surface. However, the mechanism of this gliding motion is unknown. Most bacteria are aerobic, they require free oxygen to carry on cellular respiration. Some bacteria, called facultatibe anaerobes can live in either the presence or absence of free oxygen. They obtain energy either by aerobic respiration when oxygen is present or by fermentation when oxygen is absent. Still other bacteria cannot live in the presence of oxygen. These are called obligate anaerobes. Such bacteria obtain energy only fermentation. Through fermentation, different groups of bacteria produce a wide variety of organic compounds. Besides ethyl alcohol and lactic acid, bacterial fermentation can produce acetic acid, acetone, butyl alcohol, glycol, butyric acid, propionic acid, and methane, the main component of natural gas. Most bacteria are heterotrophic bacteria are either saprophytes or parasites. Saprophytes feed on the remains of dead plants and animals, and ordinarily do not cause disease. They release digestive enzymes onto the organic matter. The enzymes breakdown the large food molecules into smaller molecules, which are absorbed by the bacterial cells. Parasites live on or in living organisms, and may cause disease. A few types of bacteria are Autotrophic, they can synthesize the organic nutrients they require from inorganic substances. Autotrophic bacteria are either photosynthetic or Chemosynthetic. The photosynthetic bacteria contain chlorophyll that are different from the plant chlorophyll. In bacterial photosynthesis, hydrogen is obtained by the splitting of compounds other than water.
An experiment was now required to figure out the agent responsible for the disease. First, scientists did intensive testing on specimen from patients and tissues taken from autopsies. Epidemiologists were able to learn that the cause of the agent was not any known microbial agent, so they hypothesized that the disease was probably caused by some unknown organism that
The abnormal presence of bacterial growth can be inspected under a microscope. If the organism inspected is not the bacteria used in the experiment, it means that the growth of the bacterial culture investigated is absent. By using this method, contamination by foreign substances in the surrounding air can be ruled out and the results would be more accurate.
There is also the potential of human error within this experiment for example finding the meniscus is important to get an accurate amount using the graduated pipettes and burettes. There is a possibility that at one point in the experiment a chemical was measured inaccurately affecting the results. To resolve this, the experiment should have been repeated three times.