Lab Report

5 Remaining in the darkroom move print to tray of running water, do 30-45 second rinse. Squeegee print, place on flat tray.

The Staphylococcus aureus bacteria belongs to the Staphylococcaceae family. It is small, round shaped, and non-motile. Staphylococcus aureus stains gram positive and can often be found in small clusters (Mandal, 2010). It often forms chains and is a large contributor of soft tissue infections. It is of a yellow color, hence the name ?aureus? which comes from the Latin term ?aurum? for gold (Orenstein, n.d.). Staphylococcus aureus is found in a few spots on the human body, such as the nasal passage, the skin, the oral cavity, and even the gastrointestinal tract. Staphylococci and Streptococci are two different strands of the bacteria and are very hard to distinguish from one another. In order to tell the difference between them, without a microscope, a catalase test needs to be performed. The test is undergone by adding 3% hydrogen peroxide to both samples. Since Staphylococci are catalase positive, meaning they produce catalase, they will produce O? while the Streptococci will not because Streptococci are catalase negative (Todar, n.d.).

Using a differential stain then allows bacteria to be divided into two groups: Gram positive, which retain the crystal- violet dye due to a thick peptidoglycan layer and Gram negative which can be decolourised to allow a counterstain of safranin.10 This is due to a thin peptidoglycan layer and an additional outer membrane composed by phospholipids

The morphology of Staphylococcus aureus is gram-positive cocci which look similar to grape like clusters under the microscope. S. aureus is also non-motile, negative for oxidase, positive for catalase, facultative anaerobic, and doesn’t form spores. When grown on certain types of agar it could grow yellow/golden colonies.

After swabbing some microbes from my cheek, I spread the bacterial smear on the slide. In order to make them stick to the slide, I hold it near a heat source so they can attach. Then I flood crystal violet on the smear. The color of violet binds to the Gram positive cell membranes and to the outer membrane of Gram negative. After waiting about a minute for the dye to be stain both cells violet, iodine is added to form a strong bond

Streaking, created by Robert Koch, is a technique used to isolate a pure stain of species of microorganism . Samples are taken from the resulting

In order to conduct the skin microflora lab, the materials that were used were: plates of S.aureus, S.epidermidis and S.pyogenes, a DEMO Mannitol Salt agar (MSA) +/- plate, simple stain reagents, 3% hydrogen peroxide (H2O2), plasma, sterile water and swabs, a Phenylethanol agar (PEA) plate, a sterile inoculating loop, a MSA plate and microscope slides.

After the 48 hours of incubation, both slants were move to the refrigerator for five days. To start the staining process, two smears were made from both slant A and slant B. To perform this, a small amount of the bacterial species was aseptically transferred and mixed into a drop distilled water in the center of both slides.1 After both smears air dried, a Gram stain was performed on each smear. To divide the unknown bacteria into the 2 board categories of Gram + and Gram -, a series of staining took place.

Allow the slide to dry completely, once dry heat fix the slide by passing holding the corner and passing the slide through a Bunsen burner flame, do this quickly as to not cause the bacteria to unstick from the slide, but slow enough to kill the bacteria to allow for staining. 4.

Species, like Micrococcus, are non-fermenters of mannitol and therefore, remain phenol red (Mahon et al. 2011).

For this experiment, we were given three gram staining slides as well as a petri dish with five different types of incubated microorganisms that were divided. The five different organisms on the petri dish being observed were Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Klebsiella pneumonia, and yeast known as Candida albicans. On the surface of the

VIII. Transferred the gel to a sensitizing reagent on a shaker for 30 min and washed the gel 2 to 3 times with ultra pure

S. aureus is one of over thirty identified staphylococci species and is distinguished from the other staphylococci species by the golden coloration of its bacterial colonies (Foster, 1996; Lowy, 1998). Carotenoids, which function to protect the bacteria from oxidants produced in the immune system, are responsible for the characteristic gold color (Liu et al., 2005 as cited in Plata, Rosato, & Wegrzyn, 2009). The bacteria have a round shape, approximately 0.5-1μm in diameter and form clumps during growth. S. aureus is one of two coagulase positive staphylococci indicating its ability to clot blood plasma. This type of bacteria is

The coagulase-positive staphylococci create the most pathogenic species of S aureus. They are common commensal and opportunistic pathogens while the coagulase-negative staph constitutes S epidermidis. The C-NS are common commensal pathogens of the skin. The clusters emerge because staph is separated in two planes. The structure of the cocci makes it easier to differentiate between the staphylococci and streptococci (Harris et al.2002).

4. Spot the solution on a TLC plate and check with UV light to see