Microbiology, 2021

556 13 • Review Questions
32. What is the advantage of HTST pasteurization
compared with sterilization? What is an
advantage of UHT treatment?
33. How does the addition of salt or sugar help
preserve food?
34. Which is more effective at killing microbes:
autoclaving or freezing? Explain.
35. Which solution of ethyl alcohol is more effective
at inhibiting microbial growth: a 70% solution
or a 100% solution? Why?
Critical Thinking
40. When plotting microbial death curves, how
might they look different for bactericidal versus
bacteriostatic treatments?
41. What are the benefits of cleaning something to a
level of cleanliness beyond what is required?
What are some possible disadvantages of doing
so?
42. In 2001, endospores of Bacillus anthracis, the
causative agent of anthrax, were sent to
government officials and news agencies via the
mail. In response, the US Postal Service began
to irradiate mail with UV light. Was this an
effective strategy? Why or why not?
36. When might a gas treatment be used to control
microbial growth instead of autoclaving? What
are some examples?
37. What is the advantage of using an iodophor
rather than iodine or an iodine tincture?
38. Why were chemical disinfectants once
commonly compared with phenol?
39. Why is length of exposure to a chemical
disinfectant important for its activity?
43. Looking at Figure 13.29 and reviewing the
functional groups in Figure 7.6, which
alkylating agent shown lacks an aldehyde
group?
44. Do you think naturally produced antimicrobial
products like nisin and natamycin should
replace sorbic acid for food preservation? Why
or why not?
45. Why is the use of skin disinfecting compounds
required for surgical scrubbing and not for
everyday handwashing?
46. What are some advantages of use-dilution and
in-use tests compared with the disk-diffusion
assay?
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