Lab Report On Gram Negative Bacteria

An unknown bacterium was handed out by Dr. Honer. The appropriate tests were prepared and applied. The first procedure that was done was the gram stain. Under a microscope, if the gram stain is purple, the bacterium is gram positive, if the stain is red, it is gram negative. The next test was the fermentation tests for glucose, sucrose and

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 experiment was conducted to find the genus and species of an unknown bacteria prescribed by the lab teacher, which was unknown bacteria GA3 in my case. Identification of unknown bacteria techniques are used on an every day basis to figure out what type of bacteria it is and to find the best method of how to treat a patient with this bacteria (1). All five “I’s” of Microbiology were used in the testing for the unknown culture. Inoculation was used several times to put the unknown culture into agar plates or into biochemical test tubes. After Inoculation of these tubes or plates, they always were placed into the incubator for further growth and development. Isolation was used to make sure we got the correct bacteria we were testing for. After each further isolation, we gram stained the culture and inspected the culture under a microscope to further help in the identification process of the unknown bacteria. Multiple tests were done on the unknown culture to make sure we were confident in what kind of bacteria the unknown was.

Citrobacter Freundii is a species of bacteria that can be potentially harmful to humans. It is known to cause meningitis by protruding into the brain and replicating itself (1). The Citrobacter species has also been found as a cause of some urinary tract infections, diarrhea, and even gastrointestinal diseases and symptoms (3). C. Freundii can be located in a wide variety of soils and water (3). Lastly, it is also the cause of many nosocomial infections due to its presence in water (1).

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

In this experiment, an unknown bacterium was given to each individual student. The main purpose of this lab was to identify the given unknown bacteria going through a series of biochemical tests as one of the gram negative bacteria among six different Gram negative bacteria Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa and Salmonella typhimurium. At the very beginning, streaking method; T-streak technique was used to isolate the pure colonies. For the morphological identification of unknown bacteria, Gram Stain Method was done. Biochemical tests that were conducted for the experiment

An unknown bacterium 15 was awarded and labeled at the table ready to be identified. Using the skills and test that are taught and learned in microbiology were applied into learning what the unknown bacteria culture was. There were multiple procedures and test done in order to gain all the information needed to determine which bacteria was given. In order to find what the bacteria was the first step was finding the right environment and temperature that would allow the bacteria to thrive and grow. Determining this is one of the most important steps in being able to obtain conclusive results that would allow the results of the test to be accurate and correct. Without the correct temperature and environment the bacteria will give inconclusive results which will alter and skew the end results and may lead to the wrong conclusion. By using the methods that were obtained and learned through the microbiology class allowed the skills and knowledge to determine the bacteria and execute the tests in order to determine the culture.

In the world of microbiology it is vitally important to be able to discern the identities of microorganisms. Not only is it important in a lab setting but as well as in healthcare in general. Properly identify what strain of bacteria a person has will aid in the proper medicine and dose given. Throughout the semester we have learned about different types of bacteria and certain test that can clearly identify them. The purpose of this lab report is to identify a Gram-positive or Gram-negative bacterium. Using all the knowledge of procedures and lab techniques identify the unknown and discuss all the tests you performed.

The bases of this experiment was to discover the identify of the unknown from three possible specimens: Klebsiella pneumonia, Escherichia coli, and Enterobacter aerogenes. Utilizaing the T streak technique, the bacteria was isolated into pure colonies for further study. The Gram Stain method was used to identity the morhphology of the bacteria such as the shape and whether the bacteria was Gram positive or Gram negative. Biochemical test were also used to help identify the unknown bacteria. The biochemical test used was the Triple Sugar Iron Agar, Sulfur Indole Motility test, Methyl Red test, Voges-Proskauer test, Citrate test, Urease test, and the Gelatin test. After observing the morphology of the bacteria using the Gram Stain method and utilizing all the possible biochemical test, the bacteria was identified to be Enterobacter aerogenes.

Then I moved onto the Phenol Red Arabinose test which shows whether the bacteria can ferment the sugar arabinose. My tube was yellow so it was positive for arabinose which brought it down to two bacteria either E. coli or C. koseri. The last test was the Citrate test which reveals if an organism can use citrate as a source of carbon and contains bromthymol blue as the pH indicator. My negative organism came out with no color change or growth so it did not utilize citrate so my organism was identified as E. coli. For my gram positive, it was immediately identified as cocci so I knew it was not B. cereus or B. subtilis.

In this experiment, the soil sample that was used in the first experiment was used for even further characterization. A colony was chosen from one of the group member’s bacteria and was amplified with PCR and had gel electrophoresis conducted in order to obtain a sequence. The purpose of this was to figure out the DNA base sequence of the 16S RNA gene from the group member’s colony that was chosen. Then, the BLAST website would be used to determine what the unknown organism was based on the sequence. Additionally, each of us performed a line streak with Streptomyces, E. coli, and S. epidermidis in order to test for the presence of antibiotics.

Introduction The Gram stain is a technique used to differentiate between two major groups of bacteria based on the composition of their cell wall. It was developed by Hans Gram in 1882. There are three primordia steps. The cells are first stained with crystal violet (followed by a mordant), then they are decolorized with 95% alcohol, and finally counterstained with safranin. Gram positive cells have a thick peptidoglycan layer that entraps the crystal violet and prevents decolorization.

The following catalase negative microbe was eliminated: Sarcina aurantiaca. The remaining catalase positive microbes remained: Staphylococcus aureus and Staphylococcus epidermidis. The next test performed was the MSA Streak Plate.

Several experiments were conducted on a sample of retail turkey meat to identify the species of a bacterium as Enteric. Enteric bacteria is a microorganism known to colonize in the GI tract of animals and humans. Enteric bacteria, if pathogenic, can have negative side effects such as diarrhea, dysentery, and other lower intestinal issues. Series of tests were conducted on isolates to determine if the sample met the metabolic, physiological and antimicrobial characteristics of Enteric bacteria. We discovered that the isolate presented enteric bacteria and was identified to be Escherichia coli. This paper will include the process taken to identify the bacteria including an introduction with a description of E. coli, a list of materials

Another purpose of this experiment is to stress the importance of knowing the identity of a microorganism. Knowing the species of microorganism present in a sample provides a