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Questions and Answers
What is the most important environmental factor controlling microbial growth?
What is the ideal growth condition for a microbe in terms of temperature?
What happens to enzymes and proteins above the maximum temperature supporting growth?
What is the effect of temperature on the cell membrane in microbial growth?
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What is the cardinal temperature that controls microbial growth?
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What is altered in the cell membrane composition depending on growth media?
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When do organisms adapted for growth at cold temperatures perform better?
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What is the correct atmosphere required for microbial respiration?
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What is the primary factor preventing microbial growth when the environment is too hot or too cold?
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What dictates microbial growth and the distribution of microbes?
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Which type of bacteria can form spores for protection from adverse conditions?
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What is the optimal growth temperature for psychrophiles?
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What type of enzymes are structurally different and have a unique membrane structure in psychrophiles?
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What is used for storing bacterial cultures at low temperatures such as -20oC and -80oC?
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What greatly affects microbial growth and has most microorganisms growing best at pH 6 – pH 8?
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What affects microbial growth and has different requirements for aerobes, microaerophiles, anaerobes, and facultative anaerobes?
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What dictates water availability in cells by controlling osmosis?
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What can attract water into the cell and allows growth in high salt concentrations?
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What can kill bacteria in neutrophils through the production of reactive oxygen species (ROS)?
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What triggers spore formation in bacteria?
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What makes bacterial spores resistant to adverse environmental conditions?
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Which bacterial diseases are transmitted to humans through spores?
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What is the usual source of human infection with anthrax spores?
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What is the primary reason for the difficulty in treating biofilm infections?
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In what type of environments do microbes grow in complex communities called biofilms?
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What is the treatment for anthrax disease involving high fever and bacteraemia?
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What do biofilms form when bacteria adhere to surfaces and excrete slimy glue-like substances which anchor the cells?
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What is the temperature and pressure required for proper sterilization to eradicate bacterial spores?
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What is the usual source of human infection with anthrax spores?
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What is the primary reason for the difficulty in treating biofilm infections?
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Study Notes
Microbial Growth and Survival in Extreme Environments
- Psychrophiles thrive in cold temperatures (approx 2oC) and have an optimal growth temperature of 15oC or lower.
- Enzymes in psychrophiles are denatured at moderate temperatures, but cold-active enzymes are structurally different and have a unique membrane structure.
- Water-miscible liquids like glycerol and DMSO at low concentrations are protective, routinely used for storing bacterial cultures at -20oC and -80oC.
- Thermophiles and hyperthermophiles flourish in high temperature environments, with archaea being more thermophilic than bacteria.
- Protein/enzyme stability at high temperatures is facilitated by critical amino acid substitutions and alternative membrane composition.
- pH greatly affects microbial growth, with most microorganisms growing best at pH 6 – pH 8, while acidity and alkalinity can greatly affect growth.
- Water availability is dictated by the concentration of solutes, with osmosis being controlled in cells by the cytoplasmic membrane.
- Halophiles and osmophiles can grow in high salt and sugar concentrations, respectively, and compatible solutes attract water into the cell.
- O2 affects microbial growth, with aerobes, microaerophiles, anaerobes, and facultative anaerobes having different oxygen requirements.
- Some Gram-positive bacteria can form spores, providing protection from adverse conditions, while Gram-negative bacteria cannot form spores.
- Spore formation in bacteria is triggered by adverse environmental conditions, and spores introduced into a wound site can germinate and cause infection.
- Oxygen killing bacteria in neutrophils can occur through the production of reactive oxygen species (ROS) and bacterial sporulation provides protection.
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Description
Test your knowledge of microbial growth and survival in extreme environments with this quiz. Explore the adaptations of psychrophiles, thermophiles, and halophiles to their respective habitats, and learn about the impact of temperature, pH, water availability, and oxygen on microbial growth. Understand the formation of bacterial spores and their role in protecting bacteria from adverse conditions.
