Culturing Bacteria Lab
PURPOSE: To determine which location (the gym, the cafeteria, or the area near the parking lot door) within Middlefield Collegiate Institute will have the greatest number of bacteria.
HYPOTHESIS: At Middlefield Collegiate Institute, the gym will have the most bacteria, the cafeteria will have the second most bacteria and the area near the front door will have the least bacteria. This is evident because the gym is a moist and warm environment which will make the gym a suitable place for bacteria to thrive. Likewise, the cafeteria is warm and many people visit it occasionally, thereby making it a possible location for bacteria to cultivate. However, the cafeteria will be more sanitized in order to ensure that students
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The swab was exposed to the air when travelling to and from the location bacteria was supposed to be collected from. Hence, air-borne bacteria could have been introduced to the swab, thus, the bacteria cultivated on the petri dish for a particular quadrant could not have been solely from one location.
2. The bacteria may not have been incubated at exactly 30˚C, as the thermometer on the incubator has an uncertainty of 1˚C. Thus, impacting the bacterial growth on the petri dish.
CONCLUSION The floor of the parking lot entrance has the greatest number of bacteria within Middlefield Collegiate Institute as, the most bacteria were cultivated in quadrant two of the petri dish containing the nutrient-rich agar medium.
EXTENSION
QUESTIONS
D) The agar plates were incubated at 30˚C and not at the body temperature of 37˚C because incubating at 37˚C will encourage the growth of pathogens if they are present in the sample. Specifically, pathogens are threatening for human health and the growth of pathogens within a school environment would be hazardous to
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The similarity indicates that all the quadrants had some of the same bacteria in it which made some colonies the same. However, other colonies were different as, different bacteria were present in each quadrant. This can be explained because all of the Q-tips were exposed to the air before they were swabbed on the agar medium, hence, similar air-borne bacteria can be present in each quadrant resulting to similar colonies within each quadrant. Also, the area swabbed may have similar bacteria because they can all thrive in the same conditions, hence some colonies may look similar.
F) If colonies appeared on the control quadrant, I can conclude that the experiment was flawed. In other words, the results were inaccurate as, there were air-borne bacteria that also reproduced in the agar plate. Thus, the bacteria present in each quadrant were not solely from one location hence, the amount of colonies and their physical appearances in a quadrant would be erroneous, affecting the results.
G) The locations of the bacterial sources ranked from least growth to most growth would be as follows: cafeteria table, large gym floor, and the area near the parking lot
I identified the genus and species of an unknown bacterial culture, #16, and I applied the following knowledge of morphologic, cultural and metabolic characteristics of the unknown microorganism according to the laboratory manual as well as my class notes and power point print outs. I was given an incubated agar slant labeled #16 and a rack of different tests to either examine or perform myself; the tests are as follows: Gram Stain; Nutrient Gelatin Test; Carbohydrate Fermentation; Dextrose, Lactose and Sucrose; IMVIC tests; Citrate, Indole, Mythel-Red and Vogues Proskauer test; as well as a Urease and TSI Test. Materials and Methods/Results Upon receiving the Microorganism (M.O.) #16, I prepared a slide by cleaning and drying it. Then, using a bottle of water I placed a sterile drop of water on the slide and used an inoculating loop, flame sterilized, I took a small sample of the unknown growth in my agar slant and smeared it onto the slide in a dime sized circle and then heat fixed it for ten minutes.
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They can be found anywhere and identifying them becomes crucial to understanding their characteristics and their effects on other living things, especially humans. Biochemical testing helps us identify the microorganism present with great accuracy. The tests used in this experiment are rudimentary but are fundamental starting points for tests used in medical labs and helps students attain a better understanding of how tests are conducted in a real lab setting. The first step in this process is to use gram-staining technique to narrow down the unknown bacteria into one of the two big domains; gram-negative and gram-positive. Once the gram type is identified, biochemical tests are conducted to narrow down the specific bacterial species.
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I also inoculated a tryptic soy broth (TSB), a nutrient gelatin deep, a motility agar deep, a fluid thioglycollate medium (FTM) tube, and a TSA plate with my unknown culture. All of these inoculated media were incubated until the next class period (about 48 hours). Then when I came to class most of my inoculated tubes and my streak plate appeared to have growth. The next step I took was making a gram stain to determine the gram reaction and cellular morphology of my unknown. I used my working slant to do this, after careful examination of the gram stain, I learned that my unknown was a gram-positive bacterium. I then preceded by making a negative stain to see the size of the cells of my unknown bacteria. The cell shape was cocci and the cells occurred in clusters of tetrads. After discovering that my unknown bacteria was gram-positive cocci, I turned to page 207 of the lab manual to narrow down my options, there was only four out of the gram-positive list that were
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