Podcast
Questions and Answers
Which scientist developed the criteria now known as Koch's postulates?
Which scientist developed the criteria now known as Koch's postulates?
- John Tyndall
- Louis Pasteur
- Ferdinand Cohn
- Robert Koch (correct)
What did John Tyndall demonstrate about dust?
What did John Tyndall demonstrate about dust?
- It can carry microorganisms (correct)
- It is responsible for spontaneous generation
- It fixes atmospheric nitrogen
- It is necessary for the process of photosynthesis
Which role is not performed by microorganisms in nature?
Which role is not performed by microorganisms in nature?
- Fixing atmospheric carbon
- Regulating weather patterns (correct)
- Decomposing organisms to recycle nutrients
- Fixing atmospheric nitrogen
Which microorganism-related product is incorrectly paired?
Which microorganism-related product is incorrectly paired?
Which activities were demonstrated by Ferdinand Cohn?
Which activities were demonstrated by Ferdinand Cohn?
What did the germ theory of disease disprove?
What did the germ theory of disease disprove?
Which suffix is used to identify methods that cause the killing of microorganisms?
Which suffix is used to identify methods that cause the killing of microorganisms?
Which of the following treatments stops the growth of bacteria without killing them?
Which of the following treatments stops the growth of bacteria without killing them?
What factors determine whether a treatment is -cidal or -static?
What factors determine whether a treatment is -cidal or -static?
In microbial control, what does the Decimal reduction time (D-value) represent?
In microbial control, what does the Decimal reduction time (D-value) represent?
How is the effectiveness of an antimicrobial treatment commonly plotted in a microbial death curve?
How is the effectiveness of an antimicrobial treatment commonly plotted in a microbial death curve?
Which statement best describes the microbial death curve?
Which statement best describes the microbial death curve?
Which suffix indicates a method that kills targeted microorganisms?
Which suffix indicates a method that kills targeted microorganisms?
What factors determine the level of treatment required for reducing microbes on fomites?
What factors determine the level of treatment required for reducing microbes on fomites?
Which example illustrates a method that stops microbial growth rather than killing the microorganism?
Which example illustrates a method that stops microbial growth rather than killing the microorganism?
What does a D-value represent in microbial death curves?
What does a D-value represent in microbial death curves?
Which of the following factors does NOT determine the effectiveness of a microbicide?
Which of the following factors does NOT determine the effectiveness of a microbicide?
How is the microbial death rate typically expressed on a death curve?
How is the microbial death rate typically expressed on a death curve?
Why do canned foods require a higher treatment level for microbial control compared to clothing?
Why do canned foods require a higher treatment level for microbial control compared to clothing?
Which microbial control method is described by the suffix -static?
Which microbial control method is described by the suffix -static?
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Study Notes
Measuring Control of Microorganisms
-
Methods that kill microorganisms (suffix -cide or -cidal) include:
- Bactericides, which kill bacteria
- The prefix identifies the type of microbe being killed
-
Methods that stop microbial growth (suffix -stat or -static) include:
- Bacteriostatic, which inhibits bacterial growth
- Fungistatic, which inhibits fungal growth
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Factors affecting the -cidal or -static nature of a method include:
- Type of microorganism being targeted
- Concentration of chemical used
- Nature of the treatment applied
Microbial Control
- Microbial death curve:
- Describes the progress and effectiveness of an antimicrobial treatment
- Often plotted as a semi-log plot, similar to microbial growth curves
- Rate of killing remains constant as a fixed percentage of the microbial population
- D-value (decimal reduction time) measures the effectiveness of an antimicrobial treatment
- D-value is the time taken for a specific treatment to result in the death of 90% of the microbial population
Microorganisms
- Microorganisms are ubiquitous and play essential roles in nature
- They:
- Photosynthesize and fix atmospheric carbon
- Fix nitrogen and enrich soil
- Recycle nutrients back to soil when organisms die
- Benefit mankind in food production, beverage manufacturing, and vitamin production
Microorganisms and Disease
- John Tyndall showed that dust carries microorganisms
- Ferdinand Cohn established a relationship between Bacillus anthracis and anthrax
- Robert Koch developed criteria to prove that disease is caused by a microorganism
- Koch's postulates are still used today to establish the relationship between disease and microorganisms
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