PURPOSE: We are doing this experiment in order to discover which surface has the most bacteria- dangerous or safer. To do this, we are testing two different spots on a door handle, a dial on a locker, the inside of a microwave, a button on a vending machine, and the bottoms of two different shoes.
HYPOTHESIS:If we collect bacteria samples from the five spots listed above (door handle, locker dial, microwave, vending machine, bottom of shoes) than the microwave will have the most bacteria production because when viewing the environment inside the microwave, we can see how it is visually the dirtiest and may contain the most germs and bacteria from the lack of being cleaned.
MATERIAL: - Two clean petri dishes, previously filled with an agar solution - Inoculation loop - 4 Q- Tips - Incubator at an approximate temperature of 37.5 degrees - Masking tape - Markers for labelling the petri dish quadrants - Bunsen burner and lighter - Microscope slide - Small glass beaker - Tongs for the microscope slide - dH20 - Crystal Violet - Iodine - 95% Ethanol - Safranin - Absorbent blotting paper - Microscope
METHOD: 1. Divide each petri dish into four sections using the markers. Label one dish A,B,C,D and the other E,F,G,H. 2. Using a Q- Tip, swab each of the five areas listed above or whatever surfaces you prefer. For each of the eight quadrants, do a different surface. After swabbing, rub each Q- Tip on the agar solution in the petri dish. Be careful not to dig up or make dents in the agar. 3. Cover the dish with the lid and place in the incubator for up to three days. Ours stayed in the incubator from about Thursday afternoon until Monday morning. The results of our petri dishes are displayed in photos 1 and 2, with petri dish 1 in photo 1 and petri dish 2 in photo 2. 4. Once removed from the incubator, observe your grown bacteria. For example, what colour is it? How many of each colony type is there? How is the bacteria elevated? 5. Draw out your petri dish and label each quadrant. 6. Place your petri dish back into the incubator for up to two more days. Ours stayed in the incubator from Monday morning to Wednesday morning. 7. Once removed from the incubator, choose one of the petri dishes and use the quadrant with the most grown bacteria. In this situation, we chose quadrant D. 8. Sterilize the inoculation loop using the bunsen burner, then use it to scoop some of the bacteria from that quadrant, being careful not to dent the agar once again. This is shown in photo 4. 9. Take your microscope slide and drop one drop of your dH20 onto it. 10. Smear the bacteria from your inoculation loop and mix until it turns cloudy. Be sure to sterilize the inoculation loop using the bunsen burner afterwards. This is shown in photo 5. 11. Place the slide in the tongs and fix the bacteria mixture to the slide by passing the slide through a bunsen burner flame until the dH20 has evaporated. Be careful not to hold the slide in the flame for too long. This is shown in photo 6. 12. Hold the slide in the beaker and apply the Crystal Violet for about 1 to 2 minutes and rinse with dH20. Steps 12 to 14 are called a primary stain. This is shown in photos 7 and 8. 13. Next apply the Iodine for about 1 to 2 minutes and rinse with dH20. 14. Wash the slide with the ethanol until purple stops running off, about 5 seconds and then rinse with dH20 directly after. DO NOT WAIT TO RINSE THE SLIDE. This is shown in photos 9 and 10. 15. Lastly, apply the safranin for about 1 to 2 minutes, rinse with dH20, and blot dry with the blotting paper. This is called a counter stain. This is shown in photos 11 and 12 16. Disinfect and clean your working space. 17. View your slide under the microscope and define whether the bacteria is gram positive or gram negative. Gram negative will show up pink and gram positive will show up purple. This is shown in photo 14.
RESULTS: Displayed in photo 3.
ANALYSIS: Displayed in photos 13 and 14. Drawings of bacteria displayed in photo 3. Quadrant A: Band room handle 1 Quadrant B: Multi microwave Quadrant C: Miranda's locker dial Quadrant D: Bottom of shoe 1 Quadrant E: Letter A button on vending machine Quadrant F: Band room handle 2 Quadrant G: Miranda's locker dial Quadrant H: Bottom of shoe 2 CONCLUSIONS: My results did not prove my hypothesis, as I thought the microwave would produce the most bacteria. In our experiment, we found the bottom of shoe 1 produced the most bacteria, which I was surprised by. However, when I swabbed the microwave, I only swabbed one small blob inside, when I should have swabbed the whole entire interior. The microwave also could have been cleaned before, while the bottom of the shoe could be touching pretty much anything anywhere, anytime, without getting cleaned. One issue I found was that I did not collect enough data from the microwave since I did not swab the whole inside. To fix this problem, I would take samples from different areas inside the microwave, instead of just one section. If I did conduct this experiment again, I would examine more surfaces than what we did today, or choose a wider range of surfaces rather than test the same area twice, like we did for the door handle.
BACTERIA COLLECTIONS LAB: PART 2
PURPOSE: We are doing this experiment in order to test how effective common household cleaning products can be on bacteria. To do this, we are testing Lysol, bleach, hand sanitizer, and glass cleaner.
PROCEDURE: 1. Start with dividing a petri dish into four sections with a marker like done before. Use only one petri dish this time, and label it A,B,C,D. 2. Fill a small test tube with about 1 centimetre of dH20 3. Sterilize an inoculation loop using a bunsen burner and using the loop, scoop some bacteria from the same petri dish quadrant you did gram staining from. 4. Being careful not to touch the sides of your test tube, place the inoculation loop in the dH20 and stir the bacteria into the dH20. 5. Continue stirring until the bacteria is dissolved. Be sure to sterilize the inoculation loop using the bunsen burner afterwards. 6. Pour the bacteria mixture out into a new petri dish, close the lid, and swirl until it covers the entire base of the dish evenly. Do this using a plastic inoculation loop for an easier job or a metal one for a challenge. 7. Leave your dish to sit for a few minutes in order for the water to absorb. 8. Clean your test tube and sterilize the inoculator, or dispose of it if it is a plastic inoculation loop. 9. Collect 4 small paper discs, and which you will each soak in a different cleaner or control . Be sure to record which disc you will place in each quadrant. 10. Using 4 clean beakers, put a small amount of each cleaning supply into each beaker. Using tweezers, soak a paper disc in the assigned cleaner until it is wet, but not dripping. 11. Place the disc into the quadrant recorded and repeat for the other two discs. 12. Soak the last disc in distilled water, and place in the last quadrant. Tape your petri dish closed and place in the incubator upside down for up to two days. Ours stayed in from Wednesday morning to Friday morning. 13. Once removed, observe the zones of inhibition and rank in effectiveness.
TABLE: EFFECTIVENESS OF CLEANING PRODUCTS ON BACTERIA QUADRANT CLEANING PRODUCT ZONE OF INHIBITION RANK A Lysol - 9mm 1st B Bleach - 8mm 2nd C Hand Sanitizer - 5mm 4th D Glass Cleaner - 7mm 3rd
ANALYSIS:
1. Describe the appearance of your plates after the incubation time. How can you tell if your bacteria were spread evenly or not. After removing our plates from the incubator, we could see the majority of the areas had an even amount of bacteria and most were at a similar elevation. For this step, we could see the bacteria was spread evenly because most of the grown bacteria were at the same level of elevation. However, when we took our plate with the paper discs out of the incubator, the zones of inhibition around the discs soaked in cleaning products were misshapen. The areas did not have a perfect diameter, but were more lopsided, resulting in approximate diameters and estimated results. Here we could see how our bacteria may not have been spread evenly since the zones of inhibitions were not similar to a circular shape and had more of a lopsided oval circumference.
2. What is the purpose of the agar plate? Could you do this experiment without the agar? Without the incubator? The agar plate plays a big roll in the experiment, as it gives the bacteria a base to grow off of. This experiment could not have been done without the agar, as the bacteria would not grow or reproduce on its own without the help of getting energy and nutrients from the agar. The bacteria we grew was heterotrophic, which means he needs to eat sugar as its carbon source to survive. However, this experiment also couldn't have been done without the incubator. Bacteria needs a temperature of approximately 37.5 degrees to grow, and if the bacteria plates sat at room temperature or any temperature hotter or colder than that measurement, it could mess with the results. If grown in a colder temperature, the bacteria may not grow or may not grow enough, and will give us a different result from what was thought, If grown in hotter temperatures, the different types of bacteria may overpower one another or the bacteria may die, once again damaging the final conclusion.
3. Which cleaner was most effective against the bacterial growth and how do you know? Does this mean that this cleaning product would work best against all bacteria? Explain.In our experiment, the Lysol cleaner was most effective against the bacteria because it came in first place since it had the largest zone of inhibition. Since Quadrant A had the widest zone of inhibition, it killed the most bacteria and therefore could kill the most bacteria out of all the solutions in the situation of an infected area. However, this does not mean Lysol would work best against all types of bacteria. All bacteria types are different, and since some may be stronger or more dangerous than others, the Lysol may not kill as much bacteria in that situation as it did for our bacterial growth plates. The bacteria also may have the ability to mutate, and could have stopped growth from the Lysol before but may not over time.
4. Which cleaning product did the worst job at killing bacteria and how do you know? Did this surprise you? Explain. Hand sanitizer did the worst at killing our bacteria because as shown in photo 16 and the table above, this product came in last place since it had the smallest zone of inhibition. Since quadrant C had the smallest zone of inhibition, it killed the least bacteria and therefore would not kill very much bacteria in the situation of an infected area. This surprised me, as hand sanitizer has been something I have used for years, and mostly assumed it was useful from commercials and the media. From this experiment, we can understand how it is not as useful as we once thought.
5. Describe your experimental control and why it is important to the outcome of this experiment.An experimental control is the one group that shows the effectiveness of each control group. In this case, it was the disc we soaked in distilled water. Adding an experimental group helps us to compare the effectiveness of the other cleaning products to if we just used distilled water to clean a surface. Without a group to compare the rest of the products off of, we may not get the correct results or be able to differ one level of effectiveness from another.
6. Describe any sources of error in your experiment and how you could improve your results. One error I found was conducted was not collecting enough bacteria samples from the microwave. In my hypothesis, I stated how I personally thought the microwave would have the most bacteria. However, the final discovery did not support this. When swabbing the microwave, I really only took data from one area, while on the bottom of shoe 1 we went much deeper. If I were to help improve my results, I would take bacteria samples from generally everywhere inside the microwave, instead of just one small section.
7. Some types of bacteria can become resistant to cleaning products and antibiotics. Using what you know about NATURAL SELECTION, explain how this can happen. Considering how natural selection is often known as "survival of the fittest," we can say that household cleaning products can eventually develop to survive in their certain environment. For example, the bacteria that cannot fight against the cleaners will eventually die off, and the other bacteria that can will pass their strong genes on to the next offspring. Over time, only the strongest bacteria who are the most resistant to the antibiotics will remain, and there will be more room for those bacteria to grow and get stronger. As years pass, some bacteria will strengthen or develop a beneficial mutation, and as a result not be as affected by the household cleaning products and antibiotics used against it.
8. What surfaces seemed to have the most bacteria on them? Shoe 1 and Shoe 2, because when looking at our bacteria plates after incubation, those two areas seemed to have produced the most bacteria spread across the quadrant.