Lab Day 2

Results and Conclusion for Lab Day 1:

As expected, our hands 

had less bacteria

on them after we washed them.

The results from our environmental sample where inconclusive. Our quest to find bacteria on a clean plate didn't work out so well. Surprisingly, the clean plates in the cafeteria were actually clean. 

Experiment 1: Environmental Sample take 2

Materials

• sterile swab
• clean agar plate
• environmental sample

1. We put our brains together and decided to take a sample from a place that would actually have bacteria(the fountain outside of Coda).

 2. Next we inoculated the agar plate with the sterile swab and placed in the incubator. 

Stay tuned for tomorrow's lab.

Why: The purpose of this experiment was to become aware of all of the bacteria that is in the 

environment.

Experiment 2: Preparing Stock Cultures 

Materials: 

• 2 slant tubes- nutrient agar
• Nutrient broth culture
• inoculating loop 
• Bunsen burner

1. Using Aseptic technique, we inoculated a working and reserve stock with our sample on slant agar test tubes. We then put them in the incubator.

2.  We also inoculated the nutrient broth with our sample using the stab technique and put it in the incubator.

Why: Depending on the growth requirements of the bacteria and the information that the scientist hopes to gain, various types of growth media are available for culturing bacteria. The two main types of bacterial growth media used are liquid nutrient broth and solid agar. Each has their specific advantages and disadvantages for growing bacteria.

Experiment 3: Streak Plate Culture  

Materials:

• agar plate
• inoculating loop
• 4 quadrants labeled on a piece of paper

1. We set the agar plate up correctly with the different quadrants labeled.

2. Next, we inoculated each quadrant with a thin sample and put it in the incubator.

Why: In order to help us to determine the pathogen and find a pure bacterial colony, we needed to use the streak plate to isolate the bacteria. This technique is used to separate the individual cells so that, when they multiply, each will form a discrete colony. This is to ensure that only one type of organism will be present. 

Experiment 3: Pour plate culture 

 Materials:

• edvotek
• beaker
• 70% ethanol
• L shaped tool
• Bunsen burner 
• broth culture 

1. Using the edvotek, we took 200 micro liters of the broth culture 

 2. Then, Hannah gracefully dispensed the sample into the pour plate.

4. We then immersed our L shaped tool into the ethanol and held it over the flame to ensure that our plate remained sterile.

 5. Next, I used the sterile tool to spread the sample on the pour plate. I then set the petri dish in the incubator. 

Why: To find a pure bacterial colony, the same reason we used the streak plate. 

Experiment 4: Gram Stain

Materials:

• blank slide
• crystal violet stain
• slide holder
• Bunsen burner 
• bibulous paper 
• microscope

1. First we added a drop of water to the slide and put a small amount of the culture on it

2. Next, we smeared the culture and water in a circular motion, with the red marker as our boundary.

3. We then briefly put the slide over the Bunsen burner to aid in drying the slide. 

4. Then, we added the crystal violet stain over the fixed culture and let it stand for 60 seconds. 

5. Once the 60 seconds was up, we rinsed off the crystal violet with water and applied Grams Iodine to the slide and let it stand for 60 seconds. 

6. We then rinsed the slide with water and blotted it with bibulous paper to remove the excess water. 

7. Finally, we examined our finished slide under the microscope. Our bacteria was Gram positive. 

Why: The gram stain is the most important staining procedure in microbiology. It is used to differentiate between gram positive and gram negative organisms. Gram positive and Gram negative cell walls are distinguished from each other by the differences in the cell walls. Our bacteria was Gram positive.