Determine the effectiveness of the new food preservative.
BackgroundTo determine whether a newly synthesized chemical might be a useful food preservative, the chemical was tested for its ability to inhibit bacterial growth.Control500 ml of cottage cheese was inoculated with 2 ml of a 24-hr culture of Pseudomonas aeruginosa and incubated at 25°C. Five hours after inoculation, a standard plate count showed there were 200 bacterial cells/ml in the cottage cheese. After 29 hours at 25°C, there were 1,000,000 cells/ml in the cottage cheese.Experiment500 ml of cottage cheese containing the preservative was inoculated with 2 ml of a 24-hr culture of P. aeruginosa. After 6 hours of incubation at 25°C, a standard plate count was performed. There were 700 bacterial cells/ml in the cottage cheese. After 38 hours, there were 61,000,000 bacterial cells/ml in the cottage cheese.Number Log1 0.002 0.305 0.706 0.7824 1.3832 1.51200 2.30700 2.851.00 x106 6.006.10 x106 6.796.10 x 107 7.79Answer the 4 Questions1. Why were plate counts used instead of direct microscopic counts or turbidity measurements?2. How did the control cottage cheese and the experiment cottage cheese differ? Was this a fair test?3. Determine the effectiveness of the new food preservative.4. Does this type of test determine bacteriostatic or bactericidal activity?
