Activity 1 – HandWashing Activity.
Table of Contents
Procedure
- Prior to washing, fingers, with or without introduced bacteria, were used to inoculate a nutrient agar plate.
- Hands were washed and dried using paper towel from the lab, or sanitized without drying with paper towel.
- Fingers were again used to inoculate a sterile nutrient agar plate.
- Steps 2 and 3 were repeated 2 to 3 times.
- Plates were incubated at 37 degrees Celsius for 48 hours.
Figure 1. Handwashing after introduction of M. luteus and S. marcescens.
Figure 2. Bacteria were not applied to hands prior to washing.
Figure 3. M. luteus and S. marcescens were added prior to sanitizing.
Questions
Examine the figures above and answer the following questions.
1.Prior to examining the slides given, what are the expected results seen if you were to introduce your fingers to a nutrient agar plate prior to washing and after subsequent washing and drying of hands?
2.Which ones are different and which ones are similar to what is expected after washing one’s hands?
3.Give possible reasons why results in figure 1 and 2 were obtained.
4.What experiment would you perform to identify the source of additional microorganisms introduced during the cleaning process?
5.Which set of figures demonstrated the expected results of cleaning one’s hand?v
Activity 2 – Environmental Sampling
One plate was left uncovered about 15 cm from the Bunsen burner, while another was placed on a bench away from the Bunsen burner. At the end of the lab, plates were incubated at 37 degrees Celsius for 48 hours.
Figure 1. Plate was kept away from Bunsen burner.
Figure 2. Plate was placed about 15 cm from Bunsen Burner.
Questions
1.Which is more effective in reducing contamination from microbes in the environment?
2.How many different types of bacteria are visible on figure 1?
3.Are any of the microbes in figure 1 viruses? Why or why not?
4.Why are there less colonies in figure 2 (Be specific enough)?
5.What type of microbes can be visible on a plate exposed to the environment?
