Lab Day 3
Results and Conclusions for Lab Day 2
Streak plate culture experiment:
Using the dissection microscope, we found that our bacterial colonies have a circular form. They also have a rose and colorless pigmentation. The colonies covered the entire margin. Also, the organisms were raised and convex. We did not get as good of a result with the pour plate.
Experiment: Carbohydrate Fermentation
Materials:
- lactose test tube
- glucose test tube
- sucrose test tube
- maltose test tube
What: (pictures shown the next lab day)
We inoculated each test tube with our sample using the aseptic and stab technique. We then set the tubes in the incubator to detect changes for the the next lab day.
Why: Carbohydrate fermentation tests detect the ability of microorganisms to ferment a specific carbohydrate. Each type of bacteria will use different energy sources depending on the specific enzymes that bacteria possesses. The characteristics feature of the enzyme production in the bacteria enables them to use diverse carbohydrates which aids in identifying the unknown bacteria.
Experiment:Capsule Stain
Materials:
1. We took mixed together a small sample of our bacteria with a drop of water.
2. We then used another slide to spread the smear and allowed it to air dry.
3. We flooded the slide with crystal violet for one minute and then washed it with water.
4. We were then able to observe the capsule on the microscope.
Materials:
- crystal violet dye
- blank slide
- slide holder
- microscope
1. We took mixed together a small sample of our bacteria with a drop of water.
2. We then used another slide to spread the smear and allowed it to air dry.
3. We flooded the slide with crystal violet for one minute and then washed it with water.
4. We were then able to observe the capsule on the microscope.
Why: The capsule stain is a differential stain which selectively stains external capsules surrounding bacterial cells
Experiment: Acid Fast Stain
Materials:
- blank slide
- Methylene blue dye
- carbolfushsin dye
- paper towel
- acid-alcohol
1. First we mixed the bacteria with a drop of water and heat fixed it.
2. Then we covered the smear with carbolfuchsin dye.
2. Next, we placed a piece of paper towel on top of the dye and dry heated it for 2 minutes.
4.We then rinsed the slide under water.
5. We then decolorized with acid-alcohol for 15-20 seconds.
6. Next we washed the top and bottom of slide with water and clean the slide bottom well.
7.The last step was a counter stain with Methylene Blue for 30 seconds.
Why: The acid-fast stain is a differential stain which distinguishes organisms with waxy cell walls that can resist decolorization with acid alcohol.
Experiment: Endospore Stain
Materials:
- beaker
- hot plate
- slide holder
- blank slide
- microscope
1. We heat fixed the bacteria on a microscope slide.
2. Next, we placed the heat fixed slide over a steaming water bath for about 5 minutes while continuing to saturate the slide with malachite green dye.
3. Then we removed the slide from the water bath and rinsed it with water.
4. The next step was to flood the slide with counter stain safranin and then rinse again.
5. Finally, we were able to view the specimen under oil immersion.
Why: One example of an extreme survival strategy employed by certain low G+C Gram-positive bacteria is the formation of endospores. This complex developmental process is often initiated in response to nutrient deprivation. It allows the bacterium to produce a dormant and highly resistant cell to preserve the cell's genetic material in times of extreme stress.
Experiment: Hanging Drop
Materials:
- depression slide
- blank slide
- Vaseline
- microscope
2. Then we aseptically transferred a loop full of culture to the center of a coverslip.
3. We then turned the depression slide upside down. Next, we touched the cover slip gently and the oil and coverslip adhered lightly to the slide.
4. We were then able to test if our bacteria is non-motile or motile using the microscope.
5. Our bacteria was motile.
Why: to test bacteria's motility
Experiments:
Materials:
- starch agar plate
- casein plate
- Lipid plate
- Indole test tube
- Methyl red test tube
- Voges-Proskauer test tube
- Citrate test tube
- Nitrate slant tube
- Triple sugar Ion test tube
- Urea test tube
- Catalase plate
- Gaspak
- Litmus test tube
What: (Pictures shown the next lab day)
We inoculated all of the plates and test tubes. We then put them in the incubator to detect changes for the next lab day.
Why:
Each different test will help us to discover our unknown bacteria.
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