Microbial Growth in Extreme Environments
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Questions and Answers

What makes bacterial spores resistant to adverse environmental conditions?

  • Secretion of enzymes that break down toxins
  • Presence of a peptidoglycan-rich cortex layer and a keratin-like spore coat (correct)
  • Ability to rapidly mutate in response to stress
  • High internal pressure and low external pressure

    • Which bacterial diseases are transmitted to humans by spores?

  • Cholera, typhoid, tuberculosis, malaria
  • Anthrax, tetanus, botulism, gas gangrene (correct)
  • Lyme disease, Rocky Mountain spotted fever, dengue fever, Zika virus
  • Influenza, common cold, COVID-19, HIV

    • What temperature and pressure are recommended for proper sterilization to eradicate bacterial spores?

  • $100^{ ext{o}}$C, 1atm
  • $121^{ ext{o}}$C, 15psi (correct)
  • $90^{ ext{o}}$C, 20psi
  • $150^{ ext{o}}$C, 10psi

    • In which environment do microbes grow in complex communities called biofilms?

    <p>All natural environments</p> Signup and view all the answers

    What do biofilms offer to microbes?

    <p>Safety in numbers and increased resistance to adverse environmental conditions</p> Signup and view all the answers

    Which type of infections involve biofilms according to the text?

    <p>$ ext{Pseudomonas aeruginosa}$ infections in cystic fibrosis patients</p> Signup and view all the answers

    Why are biofilm infections difficult to treat?

    <p>Biofilm cells require higher antibiotic doses compared to planktonic cells</p> Signup and view all the answers

    What substance do bacteria excrete to anchor themselves and form biofilms?

    <p>Slimy glue-like substances</p> Signup and view all the answers

    What type of disease is woolsorters' disease?

    <p>Anthrax</p> Signup and view all the answers

    Which bacteria form biofilms on implanted biomaterials and catheters according to the text?

    <p>Coagulase-negative staphylococci</p> Signup and view all the answers

    What is the optimal pH range for most microorganisms to grow (neutrophiles)?

    <p>pH 6-8</p> Signup and view all the answers

    What do halophiles thrive in?

    <p>High salt concentrations</p> Signup and view all the answers

    What type of bacteria can form spores for protection from adverse conditions?

    <p>Some Gram-positive bacteria</p> Signup and view all the answers

    How do psychrophiles differ from cold-active enzymes in terms of temperature tolerance?

    <p>Psychrophiles struggle to grow in environments with varying temperatures, while cold-active enzymes allow normal nutrient transport at low temperatures.</p> Signup and view all the answers

    What is the primary factor influencing water availability and osmolarity for microbial growth?

    <p>$\text{Solute concentration}$</p> Signup and view all the answers

    What is the role of water-miscible liquids like glycerol and DMSO in storing bacterial cultures at low temperatures?

    <p>They prevent microbial growth</p> Signup and view all the answers

    What type of microbes increase internal solute concentration to obtain water and use compatible solutes?

    <p>Osmophiles</p> Signup and view all the answers

    What do thermophiles thrive in?

    <p>High temperature environments</p> Signup and view all the answers

    What happens when spores germinate in a wound site?

    <p>They cause infection</p> Signup and view all the answers

    What is the most important environmental factor controlling microbial growth?

    <p>Temperature</p> Signup and view all the answers

    What is the cardinal temperature that controls microbial growth?

    <p>Maximum</p> Signup and view all the answers

    What happens to enzymes and proteins above the maximum temperature for microbial growth?

    <p>They are denatured</p> Signup and view all the answers

    What may happen to the cell membrane below the minimum temperature for microbial growth?

    <p>It may no longer function</p> Signup and view all the answers

    What type of temperature do organisms adapted for growth at cold temperatures prefer?

    <p>$10^\text{o}C - 20^\text{o}C$</p> Signup and view all the answers

    What is altered depending on growth media with respect to cell membrane composition?

    <p>The cell membrane composition</p> Signup and view all the answers

    What are ideal growth conditions for a microbe?

    <p>A temperature where all their enzymes are folded properly and working at the optimum rate</p> Signup and view all the answers

    What do environmental conditions dictate with respect to microbial growth?

    <p>The distribution and habitats of microbes</p> Signup and view all the answers

    What effect does too hot or too cold temperature have on microbial growth?

    <p>It can prevent growth</p> Signup and view all the answers

    What is the primary focus of Koch's postulates?

    <p>Proving the association between a microorganism and a specific disease</p> Signup and view all the answers

    Which factor can make the application of Koch's postulates challenging?

    <p>Difficulty in culturing some pathogens</p> Signup and view all the answers

    What is a key differential in pathogens that helps them cause disease?

    <p>Presence of virulence factors</p> Signup and view all the answers

    Which type of toxin targets cells lining the gut tract?

    <p>Enterotoxins</p> Signup and view all the answers

    What do Clostridium botulinum and Clostridium tetanii secrete, leading to fatal paralysis?

    <p>Extremely potent neurotoxins</p> Signup and view all the answers

    Which type of factor is directly involved in causing disease?

    <p>Virulence factor</p> Signup and view all the answers

    Where are endotoxins primarily found?

    <p>In Gram-negative organisms</p> Signup and view all the answers

    Which factor primarily blocks phagocytosis by forming a barrier?

    <p>Capsules</p> Signup and view all the answers

    How do opportunistic pathogens take advantage of changes in environment?

    <p>They are already present and exploit environmental changes.</p> Signup and view all the answers

    What serves as a barrier against infections by establishing colonies?

    <p>Mucous membranes</p> Signup and view all the answers

    What triggers specific responses in acquired immunity?

    <p>Antigens recognized by antigenic determinants (epitopes)</p> Signup and view all the answers

    What may provoke allergic reactions due to their properties?

    <p>'Antigens &gt;5-100KDa'</p> Signup and view all the answers

    What percentage of the final grade is allocated to practical assessments?

    <p>30%</p> Signup and view all the answers

    When is the Practical Exam scheduled to be held?

    <p>Friday Nov 24th 2-3pm</p> Signup and view all the answers

    What is the subject of Lecture 16?

    <p>Microbiology in the Food Industry - Fermentations</p> Signup and view all the answers

    What is the primary focus of Industrial Microbiology?

    <p>Food and Beverage Industry</p> Signup and view all the answers

    Which sector does Clinical Microbiology primarily impact?

    <p>Developing vaccines, antibiotics, new treatments</p> Signup and view all the answers

    What is the percentage weightage for the end of term MCQ exam?

    <p>70%</p> Signup and view all the answers

    How many practical reports are to be submitted online after the practicals?

    <p>Two reports</p> Signup and view all the answers

    What is the role of bacteria in the biotech industry?

    <p>Producing antibiotics and probiotics</p> Signup and view all the answers

    What does Lecture 12 focus on?

    <p>Pathogenic Bacteria</p> Signup and view all the answers

    Which industry does Environmental Microbiology primarily impact?

    <p>Pollution and Bioremediation</p> Signup and view all the answers

    What does Lecture 10 cover?

    <p>Microorganisms and Disease</p> Signup and view all the answers

    What is the total weightage for practical assessments?

    <p>100%</p> Signup and view all the answers

    Study Notes

    Microbial Growth in Extreme Environments

    • Psychrophiles thrive in deep ocean waters at approximately 2oC, but struggle to grow in environments with varying temperatures.
    • Enzymes in psychrophiles are denatured at moderate temperatures, but cold-active enzymes are structurally different and allow normal nutrient transport at low temperatures.
    • Freezing prevents microbial growth and causes dehydration and ice crystal formation, but water-miscible liquids like glycerol and DMSO can protect cells and are used for storing bacterial cultures at low temperatures.
    • Thermophiles and hyperthermophiles thrive in high temperature environments, with archaea being more thermophilic than bacteria.
    • Critical amino acid substitutions and alternative membrane compositions facilitate protein and enzyme stability at high temperatures.
    • The pH scale, a log scale representing the concentration of hydrogen ions, significantly affects microbial growth, with most microorganisms growing best at pH 6-8 (neutrophiles).
    • Water availability and osmolarity, influenced by solute concentration, are crucial for microbial growth, with halophiles thriving in high salt concentrations and osmophiles able to grow in high sugar concentrations.
    • Microbes in high solute, low water environments increase internal solute concentration to obtain water and use compatible solutes, which are non-toxic and attract water into the cell.
    • Oxygen availability affects microbial growth, with aerobes, microaerophiles, anaerobes, and facultative anaerobes having varying oxygen requirements.
    • Spore formation in some Gram-positive bacteria provides protection from adverse conditions, while Gram-negative bacteria cannot form spores.
    • Bacterial sporulation can lead to infection when spores germinate in a wound site.
    • Adverse environmental conditions trigger spore formation in some bacteria.

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    MICR20010 lecture 9 2023.pptx
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    Description

    Test your knowledge on the growth and adaptation of microbes to extreme environments, from cold ocean waters to high temperature habitats and varying pH levels.

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