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Gram staining
Microbiology Identifying Bacteria
Gram staining lab answer key
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Knowing the Unknown Identifying microorganisms can provide information on diagnosing diseases and discovering the most beneficial treatment possible. The purpose of this assignment was to identify an unknown microorganism using biochemical tests and various methods that were learned in my microbiology laboratory classes. In this paper, I will discuss the processes of how I came to identify my unknown microorganism. For this experiment, I utilized unknown number three which I later identified as Staphylococcus epidermis. I concluded that the unknown organism was Staphylococcus epidermis based on numerous tests performed in the laboratory which I will discuss in detail throughout this paper. One of the first tests performed was the Gram Stain. The Gram Stain differentiates bacterial organisms according to their cell wall structure. Gram-positive cells will stain blue to purple whereas Gram-negative cells will stain red to pink (Lab Handout; Gram Stain). Upon performing the Gram Stain on my unknown, I concluded that it was a Gram-positive cell due to the purple color when viewed under the microscope. I also determined the shape to be cocci as evidenced by the spherical shape of the bacterium. In the following picture viewed with an electron microscope, you can clearly see that Staphylococcus epidermis is a Gram-positive cocci (microbiologyglossary.wikispaces.com). The Gram- positive cocci are arranged in grape-like clusters and are non-motile. They also form cohesive, white and raised colonies ranging from 1–2 mm in diameter (vetbact.org). This strain of bacteria is a facultative anaerobic organism, which means that it can grow with or without oxygen. Staphylococcus epidermis grows well on nutrient agar dishes with a temperatur... ... middle of paper ... ...denced by the agar plate remaining blue-black in color. Eosin methylene blue agar (EMB) is a medium used to isolate fecal coliforms and is selective for gram-negative bacteria against gram-positive bacteria. Sucrose and lactose serve as fermentable carbohydrate sources which encourage growth and allow one to differentiate between fermenting and non-fermenting microbes. Vigorous fermenters of lactose or sucrose will produce quantities of acid sufficient to form the dark purple dye complex which is usually associated with a green metallic sheen. Slow fermenters will produce a smaller amount of acid production and appear brown-pink in color (Lab Handout; EMB). This experiment resulted in no color change which was expected as two previous tests indicated that my unknown was a gram- positive bacteria and this test is selective for gram-negative bacteria.
Table 6 shows the results of the biochemical tests. The isolate can obtain its energy by means of aerobic respiration but not fermentation. In the Oxidation-Fermentation test, a yellow color change was produced only under both aerobic conditions, indicating that the EI can oxidize glucose to produce acidic products. In addition to glucose, the EI can also utilize lactose and sucrose, and this deduction is based on the fact that the color of the test medium broth changed to yellow in all three Phenol Red Broth tests. These results are further supported by the results of the Triple Sugar Iron Agar test. Although the EI does perform fermentation of these three carbohydrates, it appears that this bacterium cannot perform mixed acid fermentation nor 2,3-butanediol fermentation due to the lack of color change in Methyl Red and Vogues-Proskauer
The first day an unknown sample was assigned to each group of students. The first test applied was a gram stain to test for gram positive or gram-negative bacteria. The morphology of the two types of bacteria was viewed under the microscope and recorded. Then the sample was put on agar plates using the quadrant streak method for isolation. There were three agar plates; one was incubated at room temperature, the second at 30 degrees Celsius, and the third at 37 degrees Celsius. By placing each plate at a different temperature optimal growth temperature can be predicted for both species of bacteria.
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.
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. 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. These biochemical tests are process of elimination that relies on the bacteria’s ability to breakdown certain kinds of food sources, their respiratory abilities and other biochemical conditions found in nature.
The purpose of this laboratory is to learn about cultural, morphological, and biochemical characteristics that are used in identifying bacterial isolates. Besides identifying the unknown culture, students also gain an understanding of the process of identification and the techniques and theory behind the process. Experiments such as gram stain, negative stain, endospore and other important tests in identifying unknown bacteria are performed. Various chemical tests were done and the results were carefully determined to identify the unknown bacteria. First session of lab started of by the selection of an unknown bacterium then inoculations of 2 tryptic soy gar (TSA) slants, 1 nutrient broth (TSB), 1 nutrient gelatin deep, 1 motility
Staphylococcus epidermidis is classified as a bacterium. This particular bacterium is identified in laboratory testing by its forms of clusters and a violet stain. The violet stain indicates that the staphylococcus epidermidis is gram- positive meaning that it is sphere shaped and does not contain an outer cell membran). This type of Staphylococcus does not typically cause disease in healthy people. However, S. epidermidis is quite the opportunist.
G. vaginalis cells are gram-negative to gram-variable. These cells are nonmotile, small, pleomorphic rods that do not have endospores, flagella, or typical capsules. In vaginal fluid smears, the Gram reaction may vary from positive to negative (Catlin, 1992). G. vaginalis is viewed in non-crowded areas in a Papanicolaou preparation. Their morphology and staining reactions are affected by the bacteria’s physiological state. Both coccobacilli and longer forms occur in 24 hour cultures of G. vaginalis on blood agar. Their average dimensions are 0.4 by 1.0 to 1.5µm. The cells do not elongate into filaments although they can be up to 2 to 3µm (Catlin, 1992).
The purpose of this project was to identify unknown bacteria species from a mixed culture. The two unknown species were initially plated onto Tryptic Soy Agar (TSA), Eosin Methylene Blue (EMB), Mannitol Salt Agar (MSA), and blood agar plates to distinguish between the two different bacteria using colony size, color, shape, and growth characteristics. By identifying and inoculating the differing types of colonies, the two unknown bacteria were purified and able to be tested
The purpose of the lab was identify and differentiate the types of eukaryotic microorganisms with the use of a simple compound microscopes and to illustrate what was seen. To view this microorganisms prepared slides containing algae, yeast, fungi and protozoan were used. The slides were shared but each student viewed the slides individually with the use of their own microscope. Each slide was viewed at different magnifications of 4X, 10X,
This pathogen, Streptococcus pneumoniae, is a gram-positive coccus that is long shaped and usually seen in groups of pairs (Todar, 2008-2012). This pathogen ranges from o.5-1.25 micrometers, which is pretty small in size (Todar, 2008-2012). It “lacks catalase and ferments glucose into lactic acid” (Todar, 2008-2012). To grow this bacterium in the lab the best way to do it would be to grow it on a blood agar at 37 degrees Celsius and produces a green zone arou...
Bacterial growth may be controlled by many methods; the techniques relevant to this experiment include heat, ultraviolet (UV) light, and antimicrobial control. Using heat as a means of controlling bacterial growth is favorable because it is quick, safe, and cost-effective (Nester, 2007). There are two kinds of heat: moist heat, which destroys the proteins of microorganisms by boiling or steaming, and dry heat, which requires high temperatures to oxidize cell components and damage proteins by incineration or dry heat ovens (Nester, 2007). Cellular proteins are essential in carrying out important biological activities, so without them, the bacteria will not be able to survive (Nester, 2007). Moist heat is widely used to treat drinking water,
Life History and Characteristics: Staphylococcus aureus is a gram positive bacterium that is usually found in the nasal passages and on the skin of 15 to 40% of healthy humans, but can also survive in a wide variety of locations in the body. This bacterium is spread from person to person or to fomite by direct contact. Colonies of S. aureus appear in pairs, chains, or clusters. S. aureus is not an organism that is contained to one region of the world and is a universal health concern, specifically in the food handling industries.
There are numerous types of bacteria that can be found in every environment. Each bacterium has different morphology which includes shape, texture and pigment production. These bacteria also have different food requirements which are important in being able to identify a microorganism. Microorganisms are a diverse group containing all bacteria a single cell prokaryotic organism that is found in every type of environment, archea single cell microorganism that lacks nuclei and almost all microorganisms are protozoa a unicellular eukaryotic organism. By identifying the causative agent of a bacterium within an individual, an antibiotic can be developed to prevent health issues. Microorganisms are also used to make certain food products for human consumption. An example of this would be the production of yogurt. It has probiotics that help with digestive abnormalities amongst other things. Probiotics are microorganisms that are consumed to provide health benefits in the body. Probiotics work by replacing the disturbed microbe with ones that are useful to digest. With the methods that wer...
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.
The body contains bacteria both inner and outer. The human body and some of there bacteria that the body contains is mutualistic. Mutualism is where both bacteria and host, human body, benefit from each other, and need one another in order to function. This bacteria is known as normal microbiota, harmless bacteria the body has. Yet, there are circumstances where these bacteria can cause harm if it enters through a wound into unknown tissue. However, biologists have several reasons why they want to learn more about these bacteria. The first is to understand the various bacteria in the body to further know how possible infections can be caused. Second is to know about the native microbes on any one-body part, allowing physicians to know what to test for. Third find out what happens when bacteria is present in locations where they are not normally at. Lastly, to inform people about the important role these bacteria have to help the human bodies immune system, and protection against other microorganisms. This experiment deals with isolating bacteria from the throat, skin and rectum is optional. This bacteria will be grown in different agar plats. Different agar plates are used to grow specific