The bacteria did not split indole from tryptophan. After the data was collected, this test showed that this could only be Bacillius cereus, as it came out to be a positive reaction. First off, a streak plate must be done on a nutrient agar plate. We opened the petri dishes and dragged the swab over the surface of the agar using our procedure one technique. To determine the presence of catalase, drops of hydrogen peroxide were placed onto a clean microscope slide, and Gram + bacteria was transferred to the hydrogen peroxide puddle using a wood stick. These bacateria where subjected to urea test which eliminates the S.
The plate was labeled gram positive for future test. The streak plate is a qualitative isolation method; quadrant streaking is mostly done to obtain pure colonies. It is commonly used to identify members of the genus Enterococcus E faecalis and E. Some species of Streptococci do not produce hemolysins. Firstly, each of the tests in the series ruled out a possible candidate until P.
Pseudomonas aeruginosa is an oxidase positive organism. Our culture was heavy so we also put one loop of water onto the slide to dilute the sample. This was an incorrect finding because B. Finally my H2S test came back positive, which left just one. Next day, a gram stain was done as explained on Number 4 above.
The results showed the nutrient agar was only allowing one bacteria to grow. Over a two week period, eight prepared types of test media were provided to identify the assigned unknown mixed cultures. Differential media are employed to differentiate certain closely related organisms or groups of organisms. The primary objective was to isolate two different colonies within the test tube. We used selective media MacConkey Agar and Mannitol Salt Agar for isolating and inhibit growth of the gram negative bacteria and gram positive bacteria.
Some of these organisms have distinct qualities that set them apart from one another, such as the exposure to certain environments. Once H 2S is produced, it combines with the ferrous ammonium sulfate, forming an insoluble, black ferrous sulfide precipitate that can be seen along the line of the stab inoculation. The Gram negative unknown, however, was very difficult to identify. The Streptococcus and Enterococcus spp. The bacterium was added to the citrate and left to incubate for 48 hours, results showed a negative result. This test is commonly used to distinguish between the b-hemolytic streptococci: Streptococcus agalactiae bacitracin resistant and Streptococcus pyogenes bacitracin sensitive.
This involved a Bunsen burner, inoculating loop, cloths pin, microscope slide, crystal violet, gram iodine, gram safranin, decolorizer, distilled water, and a microscope. The pathogen is the leading cause of infective endocarditis, bacteremia, pleuropulmonary, skin and soft tissue, osteoarticular, and infections. The unknown gram-negative bacteria is Enterobacter aerogenes. Then we spread the bacteria from the first quadrant to the second quadrant. The only gram negative bacteria that shows a positive result on the Casein Test is Pseudomonas aeruginosa, therefore correctly confirming the unknown gram negative bacteria.
In these tests, most of the incubation times and temperatures were the same for basically the same reasons. Pseudomonas aeruginosa is a gram negative rod shaped bacteria that was first discovered in 1882 by a pharmacists named Carle Gessard 2. It is most commonly found in mammals intestines. Escherichia coli and Shigella dysenteriae are citrate negative. However, in many cases gas is produced by fermentation and further testing is necessary to determine if reduction of nitrate has occurred.
Oxidase Test: Oxidase test is an important differential procedure that should be performed on all gram-negative bacteria for their rapid identification. The result, showed a clearing or halo ring around the streak of bacterium. In the case of nonfermenters, this is indicative of reduction of nitrate to nitrogen gas. The biochemical tests were: Lactose fermentation, Tryptophan digestion Indole , Orinithine, methyl red and mannitol test. Indole test: Indole tests looks for the presence or absence of tryptophanase enzyme production of the bacteria. To decipher between which biochemical tests to perform, the gram positive and negative tables handed out by the Professor, were referred to. The first procedure performed was an isolation of the unknown bacteria with the goal of obtaining a pure culture.
The only significant disease-causing bacteria of humans that produce coagulase are Staphylococcus aureus. Catalase production and activity can be detected by adding the substrate H 2O 2 to an appropriately incubated 18- to 24-hour tryptic soy agar slant culture. This was performed to ensure that the Gram positive bacteria were well isolated from the Gram negative. After 2 days, the growth was examine as to the morphology , color and colony. This is the main reason why the identification of Bacteria in a clinical setting is so important.