Comparing The Cellular Morphology Of Table 2

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

The three organisms that were identified in my unknown tube were Citrobacter freundii, Corynebacterium xerosis, and Micrococcus. The first step of this project involved isolating the three organisms that were within the mixed culture. Once I successfully isolated them, I was able to do specific colony morphologies for each of the organisms. The characteristics of Citrobacter freundii includes butyrous, opaque, circular, convex, and beige. Corynebacterium xerosis is white, small, punctiform, circular, dry, and brittle. Micrococcus is white, large, opaque, butyrous and circular.

Preliminary studies help identify Genus species of bacteria. Two different preliminary study pathways must be used since two different pathogens were found in the sample. A dilution and a quadrant streak are the ideal methods to separate pure cultures of bacteria. MacConkey Agar and CAN (MAC) is a selective media that is used for the cultivation of gram negative bacteria. (PEA) is a selective media that is used

During the purification section of this lab, the LB/amp/ara agar plate was examined for well-isolated green colonies and the LB/amp plate was observed for white colonies with space between each other. These colonies were circled on the outside of the plates using a marker. Next, two 15 milliliter culture tubes containing 2 milliliters of nutrient growth media were obtained and labeled “+” and “-“. Using a new inoculation tube, the circled colonies from each plate were scooped out and immersed in their respective culture tubes. Once the bacteria was mixed into the solution, the tubes were sealed and placed horizontally into the 32⁰ incubator for 24 hours.

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

The purpose of this lab was to isolate and identify the microbes from the randomly assigned mixed culture in test tube number # 10. In order to achieve identification of the microbes the mixed culture will be inoculated on various media, and subjected to biochemical tests in order to differentiate and identify the microbes. These experiment were carried out over the course of five days in a microbiology lab. Isolation of two microbes for a pure culture of each was achieved by the streak plate method, and gram staining identified a gram-positive (+) microbe and a gram-negative (-) microbe. A blood agar plate was inoculated with the gram (+) microbe to reveal it was beta hemolysis.

The purpose to this lab was to isolate and identify two unknown bacteria from a mixed culture provided to us by our instructor. This study was done by applying all of the methods that have been instructed on thus far in microbiology laboratory class. Each test performed, provided us with some key information about the unknown microbes in question and how the bacteria function.

The purpose of this project was to identify the identities of two unknown bacteria in a mixed broth culture by using several separation methods. To separate the organisms, a four-way streak plate technique was used to isolate the two unknown bacteria into separate visible colonies. Then after each colony were clearly isolated; the two unknowns were processed through Gram staining test to determine the Gram stain and morphology. After Gram staining, a carbohydrate test was performed on each unknown to determine if it had glucose, sucrose, or lactose fermentation. The results of the sugar test help determining which biochemical test should be performed next. The Gram positive organism was tested through a carbohydrate fermentation test, then further tested to confirm its identity through an indole and catalase test. The Gram negative organism was tested through carbohydrate fermentation test, then further tested to confirmed its identity through an indole, and TSIA test. After running four biochemical tests, the results conclude that the Gram positive unknown was Staphylococcus aureus. S. aureus was identified based on the fermentation results of the glucose test, negative indole test, and a positive catalase production. S. aureus is a Gram positive circular shaped bacterium that is very common in the U.S and is normally found in the nose, respiratory tract, and on the skin. This bacterium is usually the most common cause of infections after injury or surgery.

From a swab from the MSA plate a lawn of bacteria will be made on a Muller-Hinton plate. Four evenly spaced antibiotic disks will be placed on the plate. The plate will be left to incubate. After an incubation period the diameter of the zone of clearing will be measured to determine the resistance of the bacteria to the antibiotics. This test is not used to determine the bacterial species; it is just used to discover what antibiotics will be the most effective. Knowing all one can form a hypothesis of this experiments outcome: it is very likely if the swabbing of the nose and remaining tests are executed properly that there will be a species of Staphylococcus detected. If the MSA plate is turned yellow by the pH indicator its probable that the species Staphylococcus aureus specifically was detected, this will be proven or disproven by the antibody agglutination test. If the MSA plate maintains a red color its still a species of Staphylococcus the specific species is just unknown. The gram stain should show a purple in color cocci clustered bacterial formation. As Staphylococcus is gram positive and has a cocci cluster

The objective of these “unknown” experiments was to take a mixed culture, which contains two unknown species, and identify those species through a series of tests. The group was informed that one species of bacteria would be a gram-negative bacillus and the other would be a gram positive coccus. The tests to be conducted ranged from streak plate isolation to biochemical tests. Each test to be conducted was discussed and agreed upon by all group members. The results of each test were analyzed by the group and led to selection of the next test that would further narrow the possible identity of the unknown species.

5 The test microscope slide was composed of a drop of B. subtilis solution placed on the left as the Gram-positive control, a drop of a solution with unknown in the middle, and a drop of E. coli solution on the right as a Gram-negative control. The slide was allowed to dry and the samples were heat fixed with a Bunsen burner. The samples were then stained with first crystal violet for one minute. After the rinsing the stain, the mordant, Gram’s iodine, was added for one minute and rinsed. A 95% ethyl alcohol/acetone solution was then applied and rinsed to de-stain the samples. Finally, Saffranin was added as the counterstain for one minute and then rinsed. Bright field microscopy, using 1000X magnification and oil immersion, was conducted to visualize first the controls, and if those results were accurate, the unknown. The three samples were observed for stain color to determine Gram classification, as well as shape and arrangement to further classify the

The streak plate method is a rapid qualitative isolation method. The techniques commonly used for isolation of discrete colonies initially require that the number of organisms in the inoculums be reduced. It is essentially a dilution technique that involves spreading a loopful of

Before plating the strains on agar plates, dilutions of the three strains of cells were prepared with LB broth.

Each mixed culture that was tested had one gram positive and one gram negative bacterial species. The possible species of bacteria that could have been isolated from the mixtures included the following: Bacillus subtilis, Corynebacterium glutamicum, Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Enterobacter aerogenes, Salmonella enterica, and Pseudomonas aeruginosa. The identities of the unknown species were determined through comparing the experimental data against data acquired from earlier experimentation.

Broth cultures of E.coli, Micrococcus luteus and Vibrio natriegens were streaked onto the respective sections. The plate was then incubated at 37oC for 48 hours. The process was then repeated on nutrient agar plates with 5, 6.5 and 10% salt.