IDENTIFICATION OF THE UNKOWN Aim: To identify bacterial organisms in a broth mixed

An unknown bacterium was handed out by Dr. Honer. The appropriate tests were prepared and applied. The first procedure that was done was the gram stain. Under a microscope, if the gram stain is purple, the bacterium is gram positive, if the stain is red, it is gram negative. The next test was the fermentation tests for glucose, sucrose and

Escherichia coli (or E. coli) is a Gram-negative, rod-shaped, facultative anaerobic bacterium found in the intestinal tract of most species of mammals and birds. E. coli cells contain pili and a flagellum. As a Gram-negative bacterium, they also contain lipopolysaccharides in the outer cell membrane. Refer to Appendix 1 for a labelled diagram of an E. coli cell.

A mixed culture of two unknown bacteria was provided by the instructor. The methods used for

The first result of importance was the result of the Gram stain. The observations of the unknown bacteria from the slant culture after Gram staining showed that the unknown bacteria were Gram negative bacilli (Image 1). After determining the unknown bacteria was Gram negative, an oxidase test was conducted on a sample from the slant culture. The cotton swap with the sample of bacteria did not change color when the oxidase reagent was applied, thus providing a negative result. With a negative oxidase test, further tests were conducted to determine various characteristics of the unknown bacteria. A MR-VP broth was inoculated with a sample from a slant culture of unknown bacteria. After incubation, the methyl red reagent was added to the broth, and the broth turned red, providing a positive result (Image 2). An EMB agar streak plate was inoculated with a sample from a slant culture of the unknown bacteria, and after incubation, growth was found on the plate, providing a positive result (Image 3). A Citrate agar slant was inoculated, and after incubation, growth was found on the media, providing a positive result (Image 4). A Urea agar slant was inoculated, and after incubation, the agar had changed from a peach color to a bright pink color, providing a positive result (Image 5). Using the flowchart (Figure 1) developed from the Table of Expected Results, the lab partners started at the oxidase test. Given the negative result of the oxidase test, the flowchart is

The purpose of this study project was to carefully isolate and identify two unknown bacteria from a mixed culture. The ability to properly evaluate biochemical test results is also necessary for the identification to be successful. The goal was to apply all of the methods and techniques that have been learned in the microbiology laboratory course for the proper identification of unknown bacteria. A certain amount of bacteria that were used throughout the course were possible bacteria that could be found in a mixed culture. The bacteria that were identified in the mixed culture were Staphylococcus Aureus and Kocuria Rhizophila.

In a laboratory setting, it often becomes necessary to identify an unknown organism. In this experiment, researchers classified an unidentified bacterium based on its physical structure, colony morphology, optimal conditions and metabolic properties. A Gram stain using crystal violet, iodine, and safranin and a simple stain using methylene blue characterized the organism’s cell wall. Cultural behavior was classified by inoculating the organism onto nutrient agar and incubating it at 37° C for 48 hours, and observing its behavior, as well as using SIM medium to test for motility. Optimal growth temperature was

The purpose of this lab was to identify two unknown bacteria cultures using various differential tests. The identification of these unknown cultures was accomplished by separating and differentiating possible

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

Unknown 12 was proved to be Proteus vulgaris. This organism was a gram-negative rod growing in single. This organism, which grew on a TSA plate, was catalase positive. A drop of H2O2 was added on to the colony and it began to bubble. Therefore, the catalase enzyme was present and broke down the peroxides in to non-toxic forms H2O and O2.

Staphylococcus aureus is a microorganism that appears on several diverse surfaces. This bacterium lives harmlessly on the skin as part of the normal flora. Hard surfaces are also covered in S. aureus. The microorganism is gram positive.

After many performed test such as the API 20E test strip, motility test, inoculated plates, gram stain, an identification flow chart which began with the results from an indole, MR, VP, and citrate test. This amongst many other test. These results brought the conclusion of my unknown culture to be Escherichia coli, my unknown number was 11.

Escherichia coli (E.coli) is a relatively large, rod shaped, gram-negative, fecal coliform most commonly found in the GI tract of warm blooded animals. There are several species of E. coli, most of which are harmless, but some are pathogenic. The most common pathogenic strain is Shiga toxin-producing E. coli, which come from the gut of farm animals and some wild game. Consumption of unpasteurized milk or meat that has not been disinfected spreads the bacterium. Symptoms include stomach cramps, diarrhea, fever and vomiting.

The result of this experiment was prevented growth of any microorganism in nutrient agar out of aseptic technique and that what we expected and we achieved to our goal of this lab. Another section of this lab, we using another technique known gram staining. Gram staining is a common technique used to differentiate two large groups of bacteria based on their different cell wall constituents4. This technique helps to identify among Gram positive and Gram negative groups by coloring these cells pink or violet. Gram positive bacteria stain violet due to the presence of a thick layer of peptidoglycan in their cell walls, which retains the crystal violet these cells are stained with.

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.

Before preparing the Gram-staining, the technique of making a bacterial slide with heat fixation was practiced. On one slide, a small drop of water was placed. Using a sterile inoculating loop, cell material from a slant stock cultural was placed into the water droplet and mixed. The slide was then left to air dry.