My original plate was inoculated by what I was hoping to be bacteria from my son’s toothbrush holder. I chose to use the toothbrush holder mainly due to the fact that I feel that toothbrush holders are very disgusting. I mean, you brush your teeth then all the water from your toothbrush sets in the bottom of the toothbrush holder where the handle of your toothbrush sits. It’s stinky and slimy, but my son feels like he just has to have one sitting on the counter top in the bathroom which, by the way, is just inches from the toilet. Sadly, shortly into the testing process, my bacteria turned out to be a fungus. Per instructor’s order, I borrowed from Abbrah Snodgrass who used the television remote from her boyfriend’s house who, by the way, is a bachelor. This just might get a little interesting. I then started my process of trying to find out if I did, in fact, have bacteria and inoculated a new plate. Abbrah states that she used her boyfriend’s remote because she felt that it would be interesting to find out just what was lurking around on it.
One of the most important biochemical test performed was to identify whether or not my bacteria was gram-positive or gram-negative, if the cell shape was bacillus or cocci and if it was a endospore or not, this would be the gram staining test which was one of the major test that was performed in the beginning. Gram staining was done under a microscope and had to be performed several different times to make sure the results came out the same. As stated by my instructor, my bacteria is not an endospore and is not acid fast but did turn out to be a gram-positive, bacillus. Another important biochemical test that was performed was to find out if my bacteria could survive with or witho...
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... what my bacteria were which was Corynebacterium xerosis.
Corynebacterium xerosis is common bacteria found on the skin of humans but rarely causes any kind of infection. This bacteria usually only becomes a problem in someone that has a compromised immune system such as with patients with blood disorders, whom have had bone marrow transplants and with an intravenous catheters. They are usually secondary infections. The most common kinds of infection include endocarditis, bacteremia, skin infections and some other illnesses such pharyngitis and pneumonia.
My bacteria made perfect sense. While using the remote, you are touching it with the skin of your hands and whatever other body part that you lay it down on. Corynebacterium xerosis is a very common bacterium that is found on the skin, so yes it makes sense, but that doesn’t mean I like the fact that it is there.
One bacterium was gram negative. It underwent four different tests. These tests were the EMB test (Eosin Mehylene Blue), the Sulfur Indole Motility (SIM) test, the Urease test, and the Simmon’s Citrate Utilization test. The EMB test checks for a bacteria’s ability to ferment lactose. This test is accomplished by placing the bacteria on Eosin Methylene Blue agar. The agar is selective for gram negative bacteria and those bacteria that can ferment lactose will have colored growth, usually a metallic green sheen.
They can be found anywhere and identifying them becomes crucial to understanding their characteristics and their effects on other living things, especially humans. Biochemical testing helps us identify the microorganism present with great accuracy. The tests used in this experiment are rudimentary but are fundamental starting points for tests used in medical labs and helps students attain a better understanding of how tests are conducted in a real lab setting. The first step in this process is to use gram-staining technique to narrow down the unknown bacteria into one of the two big domains; gram-negative and gram-positive. Once the gram type is identified, biochemical tests are conducted to narrow down the specific bacterial species.
Other human errors could have affected the results, such as not inverting the plate before putting it into incubation would not allow for bacterial growth. Not pipetting the tube up and down to mix the bacteria that settled at the bottom of the tube before starting the Gram Stain would not allow for an accurate reading because there wouldn’t be many bacteria on the slide. Passing the slide over the bunsen burner too many times, hence killing the bacteria and not allowing for a Gram Stain. If this experiment had to be redone, one improvement would be to allow for more than one plate without a point deduction. Unexpected human errors might interfere with a person’s results.
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
The Gram stain is a system used to characterize bacteria based on the structural characteristics of their cell walls. A Gram-positive cell will stain purple if cell walls are thick and a Gram-negative cell wall appears pink. Most bacteria can be classified as belonging to one of four groups (Gram-positive cocci, Gram-positive bacilli, Gram-negative cocci, and Gram-negative bacilli) (Phenotypic analysis. (n.d.).
The first step to the unknown is selecting an actual organism. The best way to select a culture is based on a high-quality distribution. Equally important, shaking up the broth tube facilitates in the distribution. Upon selection, a gram check for purity is performed. Step by step instructions for this procedure can be found in Benson’s, Microbiological Applications p. 99. Furthermore, an aseptic technique must be performed for this test and the entire tests following the unknown. The purpose of this test is to differentiate between gram positive and gram-negative bacteria. The key indicator of gram-positive bacteria is a purple stain and a pink stain for gram-negative bacteria. A slide is viewed with a microscope under oil immersion. Equally
Bacteria play a large role in our health, the environment, and most aspects of life. They can be used in beneficial ways, such as decomposing wastes, enhancing fertilizer for crops, and breaking down of substances that our bodies cannot. However, many bacteria can also be very harmful by causing disease. Understanding how to identify bacteria has numerous applications and is incredibly important for anyone planning to enter the medical field or begin a career in research. Having the background knowledge of identifying an unknown bacteria may one day aid healthcare professionals diagnose their patient with a particular bacterial infection or help researchers determine various clinical, agricultural, and numerous other uses for bacteria.
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.
Streptococcus pyogenes is a very common bacteria found in humans. It is very transmissible and can be caught through the air via coughing or sneezing. This form of Strep. illness is referred to as Streptococcal pharyngitis, also known as Strep. throat, which can complicate into Scarlet Fever. It is also possible to be infected through abrasions of the skin, which can result in cellulitis, impetigo, or even necrotizing fasciitis. Aside from human to human contact, these bacteria can also be found in unpasteurized milk. There is no vaccine for Streptococcal infections, though antibiotics such as penicillin still work very well against them.
Rautemaa, R., Nordberg, A., Wuolijoki-Saaristo, K., & Meurman, J. (2006). Bacterial Aerosols in Dental Practice - a Potential Hospital Infection Problem? Journal of Hospital Infection, 64(1), 67-81.
Dental plaque is the combination of bacteria embedded in a matrix of salivary proteins and bacterial products superimposed on the acquired pellicle (Berkovitz, et al., 2011). It is an example of a biofilm, a term used to describe relatively undefinable microbial community associated with a tooth surface or any other hard, non-shedding material (Reddy, 2008). Plaque can also be described as
Biofilms can form on many surfaces, including natural aquatic systems, human teeth, medical devices like artificial heart valves and catheters,
This may sound like the beginning of a horror movie, but it isn’t. It is actually a very basic description of a very broad subject: microbiology.
Leboffe, M. J., & Pierce, B. E. (2010). Microbiology: Laboratory Theory and Application, Third Edition 3rd Edition (3rd Ed.). Morton Publishing
When you hear the word bacteria the first thing that might come to mind would be a germ. Although there can be many harmful types of bacteria, it is an essential part of life. Bacterium is all over...