Problem
Direct microscopic counts, viable cell counts, and the turbidimetric method are all techniques for measuring microbial growth. Describe the process involved for each (including necessary materials and equipment). What are the advantages and disadvantages of each technique? Which method of measuring microbial growth would be used for the following: 1) to determine the amount of microbial contamination in a sample of milk, 2) to determine the growth curve of a culture of E. coli growing in the lab Justify your answers.
After eating chicken salad for lunch on a very warm afternoon in South Florida, you place your leftovers in your backpack and forget about them until you get home 5 hours later. As you contemplate whether to finish off those leftovers, you think back to your Microbiology Lecture earlier in the day where you learned how to calculate bacterial growth. If your chicken salad was contaminated with just 5 cells of a pathogenic bacterium that has a doubling time of 10 minutes, how would you calculate the current number of pathogenic cells?
What are the cardinal temperatures and how are they related to the growth of a microorganism? Identify the major classes of microorganisms based on optimum temperature and list the corresponding optimum temperature for each. While both bacterial and archaeal hyperthermophiles exist, the vast majority are archaeal. What structural difference in the cell membranes of bacteria and archaea might contribute to this observation?