Tanner and Alex's ISP

Question: What surfaces do bacteria grow the best on? Does hand sanitizer Really work?

Topic: We will be swabbing different surfaces and growing the bacteria from them each in 2 petri dishes one normal and one with hand sanitizer.

Critiques:Are you going to swab all the substances from the same house/classroom? (Butler) do you plan to put the bacteria in the best climate to grow or in real life situations(klekamp) How are you guys going to quantify your data? (DITMAN)

Independent Variable: The surfaces we swab will be our independent variables./ The hand sanitizer will be our other variable.

Dependent Variable: The amount of bacteria colonies that grow/The type that grow.

Hypothesis: The more the surface is used or the dirtier it is the more colonies it will have on it/the more dangerous the colonies will be.// If the hand sanitizer is added to the petri dish the bacteria will not grow.

Background Information:

-In a similar experiment, the procedure was started by washing there hands before swabbing any surface. They then dampened the end of the Q-tip and swabbed the surface they were testing. After that they wiped the Q-tip on the agar in the petri dish and threw it away. Finally they taped the petri dish shut put it in a zip-lock bag and labeled it. It also described how to make the agar solution needed to grow the protien. It said to mix ½ tsp of agar (about 1.2 grams) with ¼ cup (60 mL) of hot water and stir. Then it said to boil the mixture for one minute to dissolve the agar completely. It specified that the agar should be completely dissolved with no particles in it. After dissolving the agar it is cooled for several minutes. After cooling it is used to fill the bottom half of each petri dish. After filling each with agar loosely put the lids on and let cool overnight and harden.(Spangler, Steve)
-The best conditions for growing the bacteria is a dark, moist, warm place. The ideal temperatures are around 90 degrees ( F ) / 32 degrees ( C ). Bacteria will grow at cooler temperatures but much slower. Also you will need to turn your dishes upside down when growing the bacteria. Results should start to be seen within 2-3 days. (All About Agar)
-All the bacteria will grow into colonies. Each colony will be a small dot in the petri dish. It is very hard to count each bacteria, you would need a powerful microscope, so this method is a good alternative. By counting the colonies you will still get a good idea of which dishes have more bacteria.(How to Count Bacteria?)

Citations:

1."All About Agar." Science Fair Project Ideas, Answers, & Tools. Science Buddies. Web. 18 Feb. 2012. <http://www.sciencebuddies.org/science-fair-projects/project_ideas/MicroBio_Agar.shtml>.
2."How to Count Bacteria?" Free Science Fair Projects. Free Science Fair Projects.com. Web. 18 Feb. 2012. <http://www.freesciencefairproject.com/biology/bacteria_counting.html>.
3.Spangler, Steve. "Growing Bacteria in Petri Dishes at Steve Spangler Science." Science Projects Experiments, Educational Toys & Science Toys. Steve Spangler Science, 2012. Web. 18 Feb. 2012. <http://www.stevespanglerscience.com/experiment/growing-bacteria>.

Materials: Petri Dishes(2 for each suface)/ Sterile Q-tips/ Hand sanitizer/ Nutrient agar/ clear tape/ zip lock bags/ incubator

Procedure:

- List of Surfaces: Keyboard/ Bathroom Door Handle/ Stair Railing/ Lunch Tray/ Lunch Table/ Silverware/ Science Desk/ Regular Desk/ Computer Mouse/ Toilet Seat
1. Wash Hands before swabbing anything or creating agar.
2. Create nutrient agar and set up petri dishes from instructions in background information. Set up 2 petri dishes per surface; one will have just agar and the other will have agar and hand sanitizer.
3. Swab the surface (provided at a later date), by dampening each end of the Q-tip and swabbing each end.
4. Wipe the swabbed Q-tip in the petri dishes, one end in the normal one the other end in the dish with hand sanitizer.
5. Tape the lid onto each petri dish, seal them in a zip-lock bag, label them, and turn them upside down.
6. Repeat for each surface (provided at a later date)
7. Incubate each petri dish and record the amount of colonies in each dish each day.
(Need to decide which areas you will swab) Kerwin

Data:

NOT WIPED
Control
Control
Exp.
Exp.
Surface
Day 1
Day 2
Day 1
Day 2
Library Mouse
7%
8%
80%
85%
Lunch Table
0%
0%
1%
5%
Silverware
0%
0%
0%
1%
Library Keyboard
0%
0%
35%
38%
Bathroom Handle
15%
20%
90%
95%
Railing
20%
23%
95%
97%
Desk (229)
2%
2%
95%
95%
Desk (254)
20%
20%
80%
90%
Toilet Seat
100%
100%
100%
100%
Lunch Tray (for plates not food)
100%
100%
100%
100%

WIPED
Control
Control
Control
Exp.
Exp.
Exp.
Surface
Day 1
Day 2
Day 3
Day 1
Day 2
Day 3
Library Mouse
0%
0%
0%
1%
2%
3%
Lunch Table
0%
0%
0%
0%
0%
0%
Silverware
0%
0%
0%
0%
0%
0%
Library Keyboard
0%
0%
0%
2%
10%
17%
Bathroom Handle
0%
0%
0%
1%
5%
7%
Railing
0%
.5%
1%
.5%
1%
4%
Desk (229)
0%
3%
0%
0%
0%
5%
Desk (254)
0%
.5%
0%
0%
0%
1%
Toilet Seat
0%
0%
0%
0%
0%
0%
Lunch Tray (for plates not food)
0%
0%
0%
0%
0%
0%

Pasting graphs caused internet to crash, I tried multiple times. I have printed them out and will bring them in.

Analysis:

After completing our experiment, we have definitely noticed a significant difference in the amount of bacteria growing on a surface without being wiped with a disinfectant wipe, and being wiped down with one. As we hypothesised, the surfaces with higher traffic were dirtier than surfaces with lower traffic. This means that areas where people were more likely to touch without someone cleaning it contained the most bacteria. Areas related to bathrooms or highly touched areas such as desk had the highest percentages of bacteria growth. Comparitivly, areas related to lunch items that are washed quite often were significantly lower in bacteria growth, with the exception of the lunch tray which may have been a contaminated petri dish. It is quite obvious that simply wiping a surface with a disinfectant wipe will dramatically reduce the amount of bacteria growing. Some areas had up to a 100% decrease in bacteria, while the average was around an 80%-90% decrease in bacteria growth.
--Also as a side note, we were able to clean up some of the most bacteria infested areas in the school while doing this test.

Conclusion:

Our hypotheses were: The more the surface is used or the dirtier it is the more colonies it will have on it/the more dangerous the colonies will be./ If the hand sanitizer is added to the petri dish the bacteria will not grow. Both hypotheses were mostly supported by our data. For our first hypothesis, surfaces such as desks and bathroom associated surfaces (dirty and highly used areas) had the most bacteria growing in their petri dishes. Also most things associated with lunch that are washed often had little or no bacteria, besides the lunch trays, which could have been contaminated petri dishes. For our second hypothesis, the majority of the growth on our surfaces were significantly reduced by the antibacterial wipes.

Limitations/Error Analysis:

One source of error in this experiment was accidental contamination. The lunch trays specifically i feel were a source of accidental contamination. Something used for eating would generally be cleaner. We had to reswab the lunch table because of accidental contamination as well. Petri dishes can get contaminated from the air if they are open to long or accidentally touching the dishes too close to the agar. Also they can be contaminated if the tape is not airtight. We can reduce these errors by wearing sterile rubber gloves and using sterile tape, making sure it is secure and airtight. We can also be more careful when swabbing and try to be quicker when the petri dish is open, to reduce air contamination. Another error would be failure to completley wipe down a surface for the antibacterial wipe test. In a similar experiment, you could test different surfaces using the same procedures. Also, you could do an experiment on the types of bacteria growing instead of the percentage of growth, and see which are the most dangerous.