Identifying bacteria in microbiology is a crucial aspect that allows for scientists to study the biochemical properties of the different bacterium and study how they function in svarious situations. At times they already know which microorganisms they are given and others they have to try and determine which microorganisms are present in the sample. When they are given an unknown, the best thing to do is set up a Dichotomous Key to help identify what is in the sample. A Dichotomous Key is a flowchart used when helping to determine the identity of an unknown microorganism. In order to make one, microbiologists use various phenotypic characteristics to isolate bacteria until they are the only one in the group. The easiest way is to start a key …show more content…
The first a catalase test uses hydrogen peroxide to see if it can be reduced to oxygen and water by the presence of bubbles. The next test, Bile Esculin, which is an Esculin medium that if the bacteria reacts with the ferric chloride the agar will turn black. The last test being used is a SIM test which is a few tests in one. It tests for sulfur reduction, which would turn black; motility, which shows growth around the incision and indole production, which is the removal of an amino group and its reaction with the Kovacs reagent turning a red color (Allen, 2016). The whole premise of this lab is to take an unknown sample and try and separate it into both Gram-positive and Gram-negative bacteria. …show more content…
This conclusion can be made because after gram staining it showed dark purple cocci, meaning it is Gram-positive. Then once a catalase test was done, bubble formation was absent and when inoculated into the Bile Esculin tube and incubated the agar didn’t turn black meaning it was negative. When it comes to sample B, it is concluded that it is Escheria coli. The conclusion was made due to the gram staining showing red rods, meaning it was Gram-negative Then after the SIM test was left at Room temperature for a day, no indication of sulfur reduction was present due to the tube still being clear and once the Kovacs reagent was added. Though the results ended up with E. coli according to the test results, the real end product for B should have been Enterobacter aerogenes. This could have been due to a contamination within the original sample somewhere or when the gram stain was done the majority of the rods were negative, but a few did stain positive. This then leads to the advantages and limits of biochemical testing. The advantages of performing biochemical tests are that they help reduce the time to identify the bacteria. Once the tests needed are figured out the others become unnecessary. Also, an advantage is that the tests allow for multiple tests at a time. Some limits on biochemical testing are that samples can become contaminated, leading to results that are not entirely
The following tests according to the lab manual were performed: gram stain, fermentation tubes, methyl red, vogues proskauer, sulfur, indole, motility and growing it up on MacConkey agar. The gram stain was performed incorrectly the first time. This is because the decolorizer was not on the bacterium slide for long enough, giving a false outcome.
Bacteria grows on the plate but did not change the color of the plate. This means that bacteria can tolerate bile salts, but cannot hydrolyze esculin. This test is not in-line on the list of my bacteria unknown. However, there is a positive result for Methyl Red because there is a color change of colonies that have a metallic green sheen around the center.
3. You test another new unknown bacterial sample, and find the G+C content is identical to one of the samples you have already identified, but the rRNA gene sequence contains one base that is different. What can you conclude: C.
According to my DNA analysis when inputted into the BLAST system my unknown bacteria has an eighty-six percent similarity to Micrococcus Luteus. These result deviate a bit from the results obtained in the Gideon experiment. Since, my DNA sequence result was not as high as I would have preferred this could be due to the limited amount of DNA concentration available after the PCR experiment was completed. A factor that could have allowed me to get a different bacteria species from the biochemical test could have been that the sample taken from the culture could have been contaminated. If the bacteria were not cultured properly this could also affect the results. Making a mistake during the PCR experiment
There are many reasons for knowing the identity of microorganisms. The reasons range from knowing the causative agent of a disease in a patient, so as to know how it can be treated, to knowing the correct microorganism to be used for making certain foods or antibiotics. This study was done by applying all of the methods that have been learned so far in the microbiology laboratory class for the identification of unknown bacteria. The identification process can be completed with a series of deferential stains and biochemical tests. Creating a dichotomous key helps to limit the amount of biochemical tests done on an unknown organism and by observation
The goal of this paper is to demonstrate comprehension which will fully explain why the test were chosen and how they were performed and lastly to to identify the unknown species. Material and Methods: A broth tube labeled as number 24 containing two unknown bacteria was given out by the lab instructor. To begin the identification of the unknown bacteria a streak plate was performed on a Tryptic Soy Agar (TSA) plate, using the quadrant method. The TSA streak plate was labeled at #24-1.
A Dichotomous Key was studied to identify bacteria and their relationships. Some of the organisms at the end of the Dichotomous Key had viable characteristics that separate them from different groups, and those that did not students learned how to further classify them. A Dichotomous Key is used to narrow down the search for the unknown organism tested. It is organized by phenotypic characteristics of organisms and conducts a systematic way of identifying the other unknowns. In the lab students were given a tube labeled with a number. Instructions were given to conduct a Gram stain to begin the search followed by the use of a Dichotomous Key and photos as resources to carry out the search. Instructions read to isolate and identify the unknown bacterium with both differential and selective tests to positively identify the given unknown organism. Differential tests used specifically for this unknown microorganism was BEA (Bile Esculin Agar), which interpreted results by the hydrolysis of esculin when the media is blackened around
These tests were conducted in order to determine size, shape, structure, fermentation ability, gas production, and growth patterns of the unknown organism. Broader than the scope of this lab, identification of an unknown bacterium can be vital. Unknown identification using biochemical tests can aide in outbreak containment (3) in hospitals or infection prevention. They can be used to provide accurate medication to patients with the bacteria. Also, the bacteria can be used in the management of plant growth (2).
There are many reasons for knowing the identity of microorganisms. The reasons range from knowing the causative agent of a disease in a patient, so as to know how it can be treated, to knowing the correct microorganism to be used for making certain foods or antibiotics. This study was done by applying all of the methods that I have been learned so far in the microbiology laboratory class for the identification of an unknown bacterium.
In class, we were given the task of identifying an unknown bacterium broth culture. After receiving number 69, I went through several tests to figure out what bacterium I received. First, I created a slide from my broth by putting a small amount of the unknown broth on to a clean slide and letting it dry for ten minutes. After this, I stained the slide by applying four reagents in order; crystal violet, grams iodine, decolorizer and safranin. From the stained slide, I discovered that this bacterium was gram-negative, which would determine the next couple of tests I would do to identify my unknown bacterium. I began by streaking for confluent growth from my broth culture onto a TSA plate. From the TSA plate, I aseptically transferred a loop
This project’s purpose as a whole was to receive an unknown bacteria and figure out what it is; One can figure this out by doing a series of tests. These tests include but are not limited to: gram stains, capsular stains, MacConkey agar plates, SIM, KIA, and UREA tubes, Catalase and Oxidase tests, Methyl Red and Voges-Proskauer test, and many, many more. Although that was just naming some of the tests one can do, what they are and how they’re done are further explained in the methods and reports section. Although there were many tests I was able to do, I was limited to an extent. I only had a few weeks to work on the project, and there were some unavailable tests I was unable to do.
This experiment was centered on metabolic and biochemical testing procedures. The rationale of performing these tests was to distinguish six different microbes from one another and to compare how their metabolic and biochemical processes differ from species to species to determine the unknown sample.
I chose TSA agar plate number 33 for my unknown ID. First, I made a streak plate of my bacteria in case I needed more later. Then, I performed the Gram’s stain. The Gram’s stain results were a very dark purple stain and small round clusters of bacteria. This led me to believe I had a Gram-positive cocci. Nothing went wrong with this test, the test was without a doubt positive (very dark purple), and I was very happy with how it turned out. With that information, and after looking at the Unknown ID flow chart directions given to us in the course, I decided to do a catalase test and dropped the 3% hydrogen peroxide straight on my original agar plate because there is no other option for cocci in this project, especially Gram-positive cocci. The
I saw bacteria growth on both two LB tube which was incubated at 250C and other at 370C. I used one tube for the further test, and the other was incubated at 40C to keep bacteria fresh and growth for other test. On the PEA plate, unknown bacteria did not growth, and on the EMB plate, bacteria had growth very strong. The result confirms one more time the unknown bacteria was gram negative because the PEA plate inhibited DNA synthesis of gram negative so bacteria could not grow on the PEA plate. On the other hand, EMB plate inhibited growth of gram positive so my unknown bacteria grew in this. After I recorded all my result, I continued to set up several test for the next day. Next, I set up PR fermentation test which include 3 broths glucose, sucrose, and lactose. I also set up PAD and Urea
Once the citrate utilization test was preformed and gave a positive test result the options for identification were narrowed down to six organisms. When the hydrogen sulfate test was performed and the test results came back negative the options were then narrowed down to only four organisms with K. pneumoniae being one of them. The Voges-Proskauer test was stated by the teacher to be inconclusive, showing no color change, which then lead to doing the gelatin hydrolysis test. The gelatin hydrolysis test was also negative, which at this point only two organisms were left to consider as the unknown. The last test preformed was the methyl red test since only two organisms were left and both organisms gave a different result. When the test was done the results were positive leading to the conclusion that the identification of the unknown bacteria was K. pneumoniae. All three carbohydrate fermentation test (sucrose, lactose, glucose) were also performed just to confirm the identification of the unknown organism all the broths turned yellow indicating the organism can ferment glucose, lactose, and sucrose and also had very large gas bubbles indicating that gas was produced. All of the carbohydrate fermentation test matched up perfectly with that of the biochemical test results obtained by the