Exam 7: The Control of Microbial Growth

Table 7.3 The following data were obtained by incubating the bacteria in nutrient medium + disinfectant for 24 hr, then transferring one loopful to nutrient medium (subculturing.) $\quad\quad\quad\quad\quad\quad\quad\quad \underline{\text { Doom }} \quad \quad\quad\quad\quad\quad\quad\underline{K O}$ Dilution Initial Subculture Initial Subculture 1:16 - + + + 1:32 - + + + 1:64 - + + + 1:128 + + + + $\quad\quad\quad\quad\quad\quad\quad\quad \underline{\text { Mortum }} \quad\quad\quad\quad\quad\quad \underline{\text { Sterl }}$ Dilution Initial Subculture Initial Subculture 1:16 - - - + 1:32 - + + + 1:64 + + + + 1:128 + + + + -In Table 7.3, which disinfectant was most effective against Salmonella?

Figure 7.2 A suspension of 106 Bacillus cereus endospores was put in a hot- air oven at 170°C. Plate counts were used to determine the number of endospores surviving at the time intervals shown. -In Figure 7.2, the decimal reduction time (D value) for the culture is approximately

Which one of the following does not belong with the others?

Table 7.1 A disk- diffusion test using Staphylococcus gave the following results: A 0 B 2.5 C 10 D 5 -In Table 7.1, which compound was the most effective against Staphylococcus?

Which of these disinfectants acts by denaturing proteins?