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Questions and Answers
What is the primary characteristic that distinguishes psychrotrophs from psychrophiles?
What is the primary characteristic that distinguishes psychrotrophs from psychrophiles?
- Psychrotrophs have a lower optimum growth temperature than psychrophiles.
- Psychrotrophs grow at higher temperatures than psychrophiles.
- Psychrotrophs have a wider growth temperature range compared to psychrophiles. (correct)
- Psychrotrophs are more heat-loving than psychrophiles.
Which of the following best describes the temperature range in which mesophiles thrive?
Which of the following best describes the temperature range in which mesophiles thrive?
- A range spanning from -10°C to 20°C, with an optimum growth at 12°C.
- A range from 10°C to 48°C, with an optimum growth at 37°C. (correct)
- A range extending from 0°C to 30°C, with optimum growth at 20°C.
- A range from 40°C to 72°C, with optimum growth at 60°C.
At what temperature would a hyperthermophile experience its most robust growth?
At what temperature would a hyperthermophile experience its most robust growth?
- Around 37°C.
- Around 90°C. (correct)
- Around 60°C.
- Around 12°C.
Which statement correctly describes the growth limits of bacteria concerning temperature?
Which statement correctly describes the growth limits of bacteria concerning temperature?
Which group of bacteria is most likely to include human pathogens?
Which group of bacteria is most likely to include human pathogens?
If a bacterium isolated from a hot spring can grow at 70°C, what is the most likely classification?
If a bacterium isolated from a hot spring can grow at 70°C, what is the most likely classification?
What is the minimum growth temperature of a psychrophile?
What is the minimum growth temperature of a psychrophile?
A bacterial species grows best at 20°C, but it can also grow slowly at 5°C. According to the provided content, how should this bacteria be classified?
A bacterial species grows best at 20°C, but it can also grow slowly at 5°C. According to the provided content, how should this bacteria be classified?
A laboratory technician is attempting to grow a culture of bacteria known to be a thermophile. At which of the following temperatures should she incubate the culture to achieve optimum growth?
A laboratory technician is attempting to grow a culture of bacteria known to be a thermophile. At which of the following temperatures should she incubate the culture to achieve optimum growth?
A new bacteria is discovered that is determined to have a minimum growth temperature of 68°C. What is MOST likely to be its maximum growth temperature?
A new bacteria is discovered that is determined to have a minimum growth temperature of 68°C. What is MOST likely to be its maximum growth temperature?
What is the primary mechanism by which cells maintain a stable internal pH despite fluctuations in the external environment?
What is the primary mechanism by which cells maintain a stable internal pH despite fluctuations in the external environment?
If a bacterium is classified as a neutrophile, what is the most likely pH range in which it would thrive?
If a bacterium is classified as a neutrophile, what is the most likely pH range in which it would thrive?
Which of the following bacterial species is known for its ability to tolerate a particularly low pH?
Which of the following bacterial species is known for its ability to tolerate a particularly low pH?
Which of the following best describes the environment preferred by most bacteria regarding solute concentration?
Which of the following best describes the environment preferred by most bacteria regarding solute concentration?
What is the specific role of detoxifying enzymes in bacterial cells related to oxygen metabolism?
What is the specific role of detoxifying enzymes in bacterial cells related to oxygen metabolism?
What is the definition of water activity (aw) as it relates to microbial growth?
What is the definition of water activity (aw) as it relates to microbial growth?
If a bacterium is described as an 'obligate halophile,' what specific condition must it require for growth?
If a bacterium is described as an 'obligate halophile,' what specific condition must it require for growth?
Which of the following correctly lists examples of Reactive Oxygen Species (ROS) that are toxic to cells?
Which of the following correctly lists examples of Reactive Oxygen Species (ROS) that are toxic to cells?
What differentiates osmotolerant bacteria from non-halophiles regarding their response to osmotic pressure?
What differentiates osmotolerant bacteria from non-halophiles regarding their response to osmotic pressure?
Which pH range is most conducive for the growth of fungi?
Which pH range is most conducive for the growth of fungi?
Which enzyme is responsible for converting superoxide radicals ($O_2^-$) into hydrogen peroxide ($H_2O_2$) and oxygen ($O_2$)?
Which enzyme is responsible for converting superoxide radicals ($O_2^-$) into hydrogen peroxide ($H_2O_2$) and oxygen ($O_2$)?
An organism that grows optimally in the presence of 21% oxygen, and possesses both SOD and Catalase would be classified as a what?
An organism that grows optimally in the presence of 21% oxygen, and possesses both SOD and Catalase would be classified as a what?
If a bacterial species grows equally well whether oxygen is present or absent, which two enzymes will it have?
If a bacterial species grows equally well whether oxygen is present or absent, which two enzymes will it have?
A microorganism is observed to grow at the bottom of a thioglycolate broth tube. Which of the following describes its most likely oxygen relationship?
A microorganism is observed to grow at the bottom of a thioglycolate broth tube. Which of the following describes its most likely oxygen relationship?
A bacterial species is classified as an aerotolerant anaerobe. Which of the following is accurate regarding its oxygen utilization and detoxification?
A bacterial species is classified as an aerotolerant anaerobe. Which of the following is accurate regarding its oxygen utilization and detoxification?
Which of the following statements most accurately describes a microaerophile?
Which of the following statements most accurately describes a microaerophile?
What is the role of thioglycolate in thioglycolate broth?
What is the role of thioglycolate in thioglycolate broth?
Which of the following best describes the role of catalase in bacterial cells?
Which of the following best describes the role of catalase in bacterial cells?
An organism is identified as a capnophile. Which of the following environmental conditions would best describe its ideal growth environment?
An organism is identified as a capnophile. Which of the following environmental conditions would best describe its ideal growth environment?
An obligate anaerobe lacks which of the following enzymes essential for detoxifying reactive oxygen species?
An obligate anaerobe lacks which of the following enzymes essential for detoxifying reactive oxygen species?
Flashcards
Minimum Growth Temperature
Minimum Growth Temperature
The lowest temperature at which a bacterium can grow.
Maximum Growth Temperature
Maximum Growth Temperature
The highest temperature at which a bacterium can grow.
Optimum Growth Temperature
Optimum Growth Temperature
The temperature at which a bacterium grows most efficiently.
Temperature Range
Temperature Range
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Psychrophiles
Psychrophiles
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Psychrotrophs
Psychrotrophs
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Mesophiles
Mesophiles
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Thermophiles
Thermophiles
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Hyperthermophiles
Hyperthermophiles
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Mesophilic bacteria
Mesophilic bacteria
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pH
pH
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Neutrophiles
Neutrophiles
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Acidophiles
Acidophiles
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Alkalophiles
Alkalophiles
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Osmotic pressure
Osmotic pressure
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Non-halophile
Non-halophile
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Osmotolerant/halotolerant
Osmotolerant/halotolerant
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Obligate/extreme Halophiles
Obligate/extreme Halophiles
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Reactive Oxygen Species (ROS)
Reactive Oxygen Species (ROS)
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Detoxifying enzymes
Detoxifying enzymes
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Obligate aerobes
Obligate aerobes
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Facultative anaerobes
Facultative anaerobes
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Aerotolerant anaerobes
Aerotolerant anaerobes
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Microaerophiles
Microaerophiles
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Obligate anaerobes
Obligate anaerobes
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Superoxide dismutase (SOD)
Superoxide dismutase (SOD)
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Catalase
Catalase
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Thioglycolate broth
Thioglycolate broth
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Capnophiles
Capnophiles
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Study Notes
Medical Microbiology: Microbial Growth and Nutrition
- Medical microbiology lecture notes cover bacterial growth and nutrition
- The growth curve shows four distinct phases: lag, log/exponential, stationary, and death/logarithmic decline.
- Bacteria have various temperature requirements, including minimum, optimum, and maximum temperatures.
- Growth does not occur above the maximum or below the minimum temperature.
- Different bacteria are categorized by their temperature requirements: psychrophiles, psychrotrophs, mesophiles, thermophiles, and hyperthermophiles.
- Mesophiles are the most medically significant, thriving best at 37°C, which is body temperature.
- A pH of an environment can greatly influence microbial growth, with optimal growth typically occurring in the pH range of 6-8.
- Bacteria exhibiting a preference for a lower pH are acidophiles, while those with a higher preference are alkalophiles.
- Osmotic pressure depends on the surrounding solute concentration and water activity (aw).
- aw is the ratio of the vapor pressure of a solution to the vapor pressure of pure water.
- Most bacteria prefer isotonic or hypotonic environments for optimal growth, yet some, like halophiles, tolerate or require high salt concentrations.
- Obligate aerobes require oxygen for growth, and they have both superoxide dismutase (SOD) and catalase for detoxification.
- Facultative anaerobes can survive with or without oxygen and possess SOD and catalase.
- Aerotolerant anaerobes can tolerate the presence of oxygen but do not use it for energy production while having superoxide dismutase.
- Microaerophiles require low levels of oxygen and possess SOD but may or may not have catalase.
- Obligate anaerobes cannot tolerate oxygen and lack both catalase and superoxide dismutase. These bacteria can utilize other chemical compounds as electron receptors instead of oxygen.
- Bacteria require carbon dioxide (CO2) for optimal growth. Most do not need a high concentration, but in some circumstances that can be required. These are called capnophiles.
- Some bacteria's growth is aided by substances in the broth that prevent oxidation or provide nutrients and are called thioglycolate broths.
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