Assignment task: Design an experiment where you exposed food to something 'dirty' where you might expect microbes to contaminate the food. (If possible, but the expensive organic food, the more natural the better... a lot of you had no growth because of preservatives in the food). For example you can drop bread on the floor or cough on it. Make sure to do the experiment with 1 'dirty' sample and one 'clean' control. Take observations at 24, 48 and 72 hours with a camera and submit them. For this experiment, cover the food (Tupperware or ziplock bag) so it will not dry out J You may also want to put it near a window or another warmer area of your house. You may even want to sprinkle the food with a little water (super tiny bit) before beginning? Come up with a hypothesis for this experiment. Describe your experiment below, and be sure to include your hypothesis, results and conclusions. (This is not a lab report, a paragraph or two would be fine, photos are encouraged).
Questions associated with Gram Stain and KOH Test:
Question 1) What does MPN stand for? Why do you think dilutions are needed to use in the MPN test?
Question 2) How do you know if a tube is positive or negative? Is it guaranteed that they have coliforms in the positive tubes?
Question 3) For EMB (Eosin Methylene Blue) agar, what result 'confirms' coliforms (positive test)
Question 4) The MPN mostly looks to grow E. coli as the indicator species of fecal contamination. Most E. coli is not pathogenic, and you can get many more harmful things like viruses from fecal contamination. Why is E. coli the only thing we look for in the lab to determine whether water is contaminated with fecal matter? (like why not look for the viruses?)
Questions associated with Antibiotic Producers:
Question 5) What genus of bacteria is most likely to produce antibiotics?
Question 6) How could you tell if antibiotics are actually produced? Describe for me what was done in the lab to confirm this.
Question 7) Evolutionarily, why are antibiotics produced? How concentrated are microbes in the soil (citation for this one please)? Knowing that, why do you think the soil is the most likely place to find antibiotics, compared to other environments?