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Questions and Answers
What do variations of oxygen reflect?
What do variations of oxygen reflect?
diversity of natural environments microbes can be found in
Response to oxygen is mainly a function of what?
Response to oxygen is mainly a function of what?
the type of metabolism used by organisms, as well as the presence or absence of specific enzymes
Which of the following are toxic forms of oxygen?
Which of the following are toxic forms of oxygen?
- Ozone
- Free radicals (correct)
- Peroxide (correct)
- Carbon dioxide
What are examples of oxygen enzymes?
What are examples of oxygen enzymes?
Obligate aerobes do not require oxygen.
Obligate aerobes do not require oxygen.
Microaerophiles require increased O2 and decreased CO2.
Microaerophiles require increased O2 and decreased CO2.
Anaerobes can tolerate oxygen.
Anaerobes can tolerate oxygen.
What does facultative mean in the context of oxygen requirements?
What does facultative mean in the context of oxygen requirements?
What is an Aerotolerant anaerobe?
What is an Aerotolerant anaerobe?
What does Sodium Thioglycollate broth contain?
What does Sodium Thioglycollate broth contain?
What color does Resazurin turn in the presence of oxygen?
What color does Resazurin turn in the presence of oxygen?
Sodium Thioglycollate broth contains a pink layer on top where oxygen is present and ______ in the middle and bottom where oxygen is absent.
Sodium Thioglycollate broth contains a pink layer on top where oxygen is present and ______ in the middle and bottom where oxygen is absent.
What do commercially produced GasPaks contain?
What do commercially produced GasPaks contain?
What color does the oxygen indicator strip turn where oxygen is present?
What color does the oxygen indicator strip turn where oxygen is present?
Name the control bacteria used for oxygen requirements.
Name the control bacteria used for oxygen requirements.
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Study Notes
Oxygen Requirements in Microbiology
- Variations of oxygen indicate the diverse natural environments where microbes thrive.
- Response to oxygen levels depends on metabolism types and the presence of enzymes that handle toxic oxygen forms.
Toxicity of Oxygen
- Toxic forms of oxygen include free radicals and peroxide, which can harm cells.
- Enzymes like catalase and superoxide dismutase help detoxify these harmful oxygen forms.
Types of Oxygen-Dependent Organisms
- Obligate aerobes require oxygen for survival and growth.
- Microaerophiles thrive in environments with reduced oxygen and higher carbon dioxide levels.
- Anaerobes cannot tolerate oxygen and may be harmed by its presence.
- Facultative organisms can grow in both the presence and absence of oxygen.
Special Categories of Anaerobes
- Aerotolerant anaerobes do not utilize oxygen for growth but can withstand its presence without being adversely affected.
Laboratory Techniques
- Sodium Thioglycollate broth is used to culture anaerobic bacteria and contains the oxygen indicator resazurin.
- Resazurin turns pink in the presence of oxygen, indicating oxygen levels.
- The broth exhibits a pink layer on top where oxygen is present, while the middle and bottom remain amber or colorless where oxygen is absent.
Commercial Anaerobic Conditions
- GasPaks, used in laboratories, contain hydrogen and palladium to remove molecular oxygen, creating anaerobic conditions for microbial growth.
- The oxygen indicator strip provides a visual cue, turning blue in the presence of oxygen and white when oxygen is absent.
Control Bacteria for Oxygen Studies
- Common control bacteria for studying oxygen requirements include E. coli, Micrococcus luteus, and Clostridium sporogenes.
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