Transcript Diagrams 1.1 Zones of Inhibition

Sponge Soup Lab
Background
Antibiotic or disinfectant discs are often used to determine if a particular
bacterium is susceptible to a type of antibiotic or disinfectant. If the
antibiotic or disinfectant works successfully, a clear ring (an area where
bacterial growth is inhibited) will appear around the disc in 24-48 hours.
The ring is called the zone of inhibition. Depending on how well the
disinfectant works, you will see more or less area around the disc that will
be free of bacterial growth.
Pre-Lab Questions:
1. What are the best conditions for bacteria growth?
2. What are some methods that bacterial growth can be
controlled?
3. Define the lawn of bacteria.
4. Define zone of inhibition.
5. What is the relationship between the size of the zone
of inhibition and the effectiveness of the disinfectant?
Problem: A food poisoning outbreak has swept through the town of
Newtown over the holiday break. A link has been found between infected
families and the Gobble brand turkey purchased and consumed by each
family. There were two differences between the households that became ill
and those that did not. Scientist noted that the type of cleaning
methods/agents used to clean the kitchen were different, as well as
whether or not rags/sponges were used to wash the dishes. Sponges from
the infected households were collected. Your assignment is to determine
which disinfectants work best in controlling the growth of bacteria.
Materials:
Rubber gloves
Petri dishes
Sharpie
Sponge
Paper discs
Antibacterial disinfectants
Incubator
Safety goggles
Ruler
Nutrient agar
Inoculating loop
Sterile water
Masking tape
Data Table 1.1 Type of Disinfectant Use
Zone
Name of Disinfectant
1
Sterile H2o (Control)
2
3
4
5
6
7
8
Diagrams 1.1 Zones of Inhibition
1
2
3
44
Plate 1
Plate 2
Data Table 1.2 Size of Zones of Inhibition
Zone
Name of Disinfectant
1
Sterile H2o (Control)
2
3
4
5
6
7
8
Size of Zone of
Inhibition (mm)