Unknown 10b is Staphylococcus epidermidis. According to Bergey’s Manual Staphylococcus bacteria are gram positive spherical cells that occur singly, in pairs or in irregular clusters. Unknown 10b was gram positive, spherical and occurred in clusters. Bergey’s Manual also says the bacteria grow well in high salt concentrations. Unknown 10b grew well on the mannitol salt agar. The optimum growing temperature is 30-37 degrees Celsius (Bergey’s Manual). Unknown 10b grew best at 37 degrees Celsius. The lab manual and past lab results confirmed all other test results. Unknown 10b was only able to use gamma lysis, it was unable to ferment mannitol and had no coagulase activity. When comparing to past labs it is confirmed that Unknown 10b is Staphylococcus epidermidis.
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.
Talaro , K., & Chess, B. (2012). Foundations in microbiology. (8th ed., pp. 563-564). New York, NY:
The purpose of the study is to identify an unknown microorganism using multiple microbiology lab techniques. Through this process I will gain knowledge on how to perform these techniques as well as the importance of these tests on identifying unknown microorganisms. This is significant as the goal of this course is to familiarize ourselves with the common microbiology tests as well as the microorganisms we encounter in our daily activities.
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
If the oxidase test was to be negative then the bacteria would have to be S. flexnery. S. flexneri is a bacterium that causes diarrheal disease, and it’s a “facultative anaerobe belonging to the family Enterobacteriaceae” (“Shigella flexneri”, n.d). However, if the oxidase test came as positive then the bacteria would have to either P. aeruginosa or A. faecalis (“Microbiology 20 Biochemical Unknown, 2009). Then an indole test will have to be done. An indole test is to identify if the bacteria could produce the enzyme tryptophase (SIM Medium”, n.d). If the test came as positive then unknown bacteria 2 would be P. aeruginosa (“Microbiology 20 Biochemical Unknown, 2009). P. aeruginosa is a bacterium that is the number one leading infections in humans. The bacterium is Gram negative that can lead to “endocarditis, meningitis, etc. (Friedrich.M, Dec 5, 2016). In the other hand if the bacteria came as indole negative then bacteria 2 would be A faecalis. A faecalis is a Gram-negative, rod-shape bacterium with flagella, and that belongs to the family Alcaligenaceas”, and it’s an opportunistic pathogen that induces infection (“Alcaligenes faecalis”, n.d). All in all, skills were practices to determine two unknown
The history of Ab starts when “the Dutch microbiologist, Beijerinck, first isolated the bacteria from soil using minimal media enriched with calcium acetate, in 1911” (Aoife et al. 244). From there different characteristic of Ab were noted, such as, “Ab is often found in pairs, does not use oxygen, does not produce nitrites, does not move, and it can be isolated on a MacConkey agar, which is a specific media of petri dish” (Rosenbaum et al. 10). Using a staining method, it is determined that Ab is a gram-negative bacterium, because it does take on the stain. Although, Ab can be difficult to de-stain, making it harder to distinguish between gram-negative or positive (Aoife et al 244). “It also has the ability to survive longer in any environment, even on dry surfaces, because it is resistance to desiccation, or being completely deprived
The objective of this lab was to identify unknown bacteria culture by using various differential tests. There are many reasons for knowing the identity of microorganisms including to find the correct antibiotic to treat infections the bacteria may have caused. All the methods and techniques used to identify unknown bacterium #79 was learned in the microbiology laboratory.
The tests explained above and completed to aid in the determination of the unknown bacteria were completed in a specific order which was supported with rationale and logic. A T – streak method was completed in succession to obtain a pure isolated colony. The T – streaks were completed with nutrient agar to give the organism nutrients and allow the organism to grow. Once a pure isolated colony was obtained, a Gram stain was completed which gave the Gram reaction and morphology of the bacteria.