Answer :
Germicides are substances that destroy or prevent the growth of pathogens such as bacteria, viruses, and fungi. The effectiveness of germicides is determined by their concentration and the duration of contact with the microorganism. The following table lists the germicides used in the experiment and their concentrations.
Control #1 (Sterile water):
- This control was used to ensure that the sterile technique was used when transferring bacteria from the broth to the agar plates.
Control #2 (Broth only):
- This control was used to ensure that the broth used to grow the bacteria was not contaminated.
Control #3 (Agar only):
- This control was used to ensure that the agar plates were not contaminated.
Control #4 (Lysol only):
- This control was used to ensure that the Lysol used did not inhibit bacterial growth. E. coli and S. aureus were used as test organisms. After being exposed to germicides at different concentrations, they were cultured on agar plates and incubated.
Bacterial growth was observed. The following observations were made:
- Germicide Concentration E. coli Growth S. aureus GrowthLysol 100% NG NGIsopropyl alcohol 50% NG NGIsopropyl alcohol 30% NG NGIsopropyl alcohol 10% NG NGFabuloso 50% G NGStrain 25% NG NGStrain 100% G NGFrom the table, it can be observed that Lysol at 100% concentration was the most effective against both E. coli and S. aureus as there was no growth of the bacteria.
The least effective germicide was Isopropyl alcohol at 10% concentration as there was growth observed for both E. coli and S. aureus. It can be inferred that S. aureus seemed to be more resistant to the germicides as growth was observed for most of the germicides except for Lysol. The purpose of the four controls was to ensure that the experiment was conducted in a sterile and controlled environment. They help to eliminate any extraneous variables and ensure that the observations are valid and reliable.
About Bacteria
Bacteria are a group of single-celled microorganisms classified at the domain level. Together with the Archaea domain, bacteria are classified as prokaryotes. Bacterial cells have a specific shape, such as a ball, rod or spiral, which is usually a few micrometers in size.
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