Lab Report On Unknown 32
The first test conducted on unknown bacteria 32 was the Gram stain. From this stain, unknown 32 was found to be a Gram-positive cocci. This test eliminated all possible Gram-negative bacteria, Gram-positive rods and Gram-positive spirillium. Next, the endospore test determined whether or not the Gram-positive bacteria contained endospores. With the use of malachite green, steam, and safranin it was found that unknown bacteria 32 did not contain endospores. This eliminated Gram-positive cocci Sporosarcina spp. The oxidase test is a test using an Oxidase swab. The oxidase swab contains a chromagenic reducing agent which donates its electrons to cytochrome c oxidase if it is present. If cytochrome c oxidase is present, the donation of electrons
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results in a blue/purple color within 30 seconds.
When unknown 32 was tested with the oxidase test, it was found oxidase negative. The catalase test tests for the presence of catalase which breaks down hydrogen peroxide and oxidase dismutase. A small amount of hydrogen peroxide is dropped onto a slide of unknown 32 and resulted in bubbles. This result shows that unknown 32 is catalase positive since it broke down hydrogen peroxide and oxidase dismutase which resulted in water and oxygen. This eliminated Enterococcus spp. and Streptococcus spp.
After the initial tests were conducted, five more tests were done to narrow down the genera and species. From the provided list of possible unknown genera, the only genus left was Staphylococcus. However Staphylococcus has many species, so test focused on differentiating the many species of Staphylococcus were conducted. First, to confirm that the unknown wasn’t a Micrococcus sp., the bacitracin test was used. This test confirmed that the unknown 32 was a resistant bacitracin resistant bacterium. Since Micrococcus spp. are susceptible bacteria, Micrococcus spp. were eliminated. The next test was the coagulase test which tests for the enzyme coagulase. In the presence of coagulase, fibrinogen in blood is converted to fibrin.
This conversion creates a clot which forms bound coagulase. If coagulase isn’t present, fibrinogen is not converted, leaving the blood clot free. When unknown 32 was tested with the coagulase test, the result was a runny clear mixture. This outcome is free coagulase. Therefore, unknown 32 is non-pathogenic thus confirming that unknown 32 cannot be S. aureus. Using the plate of the bacitracin test, the blood agar test results were analyzed. Unknown 32 showed growth on the blood agar plate, with a brown color. Though there was a slight color change, the color change was not a positive result for β-hemolysis nor α-hemolysis. That means that unknown 32 had γ-hemolysis. Since it is γ-hemolysis, it is a possibility that unknown 32 is S. epidermis. This hypothesis can be tested through the motility test. With an inoculating needle, unknown 32 was used to inoculate a semi-solid agar deep. After being incubated, the result showed that there was a growth diffusing from the stab line. This eliminates S. epidermis. The last of the five tests was the aerotolerance test. With the aerotolerance test, unknown 32 was used with an inoculating needle to stab an agar deep. After incubation, growth was heavily shown on the top of the agar. From this, it is concluded that unknown 32 is an obligate aerobe. However, after running the 16s rRNA through the NCBI database, unknown 32 is found to be Staphylococcus saprophyticus which is a facultative anaerobe. This mistake could have been caused by human error. It is possible that the growth was heavy on the top of the agar, making it harder to notice the growth below and throughout the agar.
results in a blue/purple color within 30 seconds.
When unknown 32 was tested with the oxidase test, it was found oxidase negative. The catalase test tests for the presence of catalase which breaks down hydrogen peroxide and oxidase dismutase. A small amount of hydrogen peroxide is dropped onto a slide of unknown 32 and resulted in bubbles. This result shows that unknown 32 is catalase positive since it broke down hydrogen peroxide and oxidase dismutase which resulted in water and oxygen. This eliminated Enterococcus spp. and Streptococcus spp.
After the initial tests were conducted, five more tests were done to narrow down the genera and species. From the provided list of possible unknown genera, the only genus left was Staphylococcus. However Staphylococcus has many species, so test focused on differentiating the many species of Staphylococcus were conducted. First, to confirm that the unknown wasn’t a Micrococcus sp., the bacitracin test was used. This test confirmed that the unknown 32 was a resistant bacitracin resistant bacterium. Since Micrococcus spp. are susceptible bacteria, Micrococcus spp. were eliminated. The next test was the coagulase test which tests for the enzyme coagulase. In the presence of coagulase, fibrinogen in blood is converted to fibrin.
This conversion creates a clot which forms bound coagulase. If coagulase isn’t present, fibrinogen is not converted, leaving the blood clot free. When unknown 32 was tested with the coagulase test, the result was a runny clear mixture. This outcome is free coagulase. Therefore, unknown 32 is non-pathogenic thus confirming that unknown 32 cannot be S. aureus. Using the plate of the bacitracin test, the blood agar test results were analyzed. Unknown 32 showed growth on the blood agar plate, with a brown color. Though there was a slight color change, the color change was not a positive result for β-hemolysis nor α-hemolysis. That means that unknown 32 had γ-hemolysis. Since it is γ-hemolysis, it is a possibility that unknown 32 is S. epidermis. This hypothesis can be tested through the motility test. With an inoculating needle, unknown 32 was used to inoculate a semi-solid agar deep. After being incubated, the result showed that there was a growth diffusing from the stab line. This eliminates S. epidermis. The last of the five tests was the aerotolerance test. With the aerotolerance test, unknown 32 was used with an inoculating needle to stab an agar deep. After incubation, growth was heavily shown on the top of the agar. From this, it is concluded that unknown 32 is an obligate aerobe. However, after running the 16s rRNA through the NCBI database, unknown 32 is found to be Staphylococcus saprophyticus which is a facultative anaerobe. This mistake could have been caused by human error. It is possible that the growth was heavy on the top of the agar, making it harder to notice the growth below and throughout the agar.