Are You Eating Bacteria?

Overview

Objectives/Goals My purpose is to do a comparative study of bacterial counts on hamburger patties sold at 5 different fast-food restaurants. I was curious about whether the hamburger was contaminated with any harmful microorganisms such as E. coli. Methods/Materials My procedures took was 4 days. On the first day, I went to Westmont College to use their biology lab to make sterile petri dishes of MacConkey and Plate Count agar media. The next day, my parents bought the condiment-free burgers from 5 fast food restaurants. At the lab, I cut 1 gram of each hamburger patty into small pieces. Then I homogenized the hamburger meat and 9 ml of a sodium chloride to make a juice. From there, I made a 10 fold dilution. I took 0.1 ml of the direct burger juice and the 10 fold dilution onto 1 MacConkey and 1 Plate Count Agar plate for each of the burgers. After completing all the plates for all the burger samples, I placed the plates into a 37 degree C incubator for 24 hours. I also did a Gram Stain Test for the two plates that had bacterial growth. This allowed me to identify that the bacterium was a gram positive bacillus. I could not do further testing because the testing would take too long and too expensive to perform tests to find the exact bacterium. Results Sample E had 1110 colony forming units per gram of meat in the undiluted Plate Count Agar sample and 1600 cfu in the 10 fold dilution sample of PCA. All the burger samples grown on the MacConkey Agar showed no signs of bacterial growth. There was no presence of E. coli or Salmonella in the hamburger patties. Conclusions/Discussion It seems that the burgers from the restaurants that I tested are safe. There was no bacterial growth in the MacConkey Agar. However, the employees of the restaurant may contaminate the hamburger if they are sick or unhygienic when preparing the burgers. If I were to do my project over again, I would also test a raw hamburger patty along with the cooked hamburger patties from the various fast food restaurants.

Competition history

• CSEF 2003 Microbiology · Entry J1336

Resources

• CSEF project summary ↗

Related projects

Closest projects by meaning, across every fair and year in the corpus.

Browse more like this

• All Microbiology projects
• CSEF Microbiology projects
• Every CSEF 2003 project