52 Questions
What makes bacterial spores resistant to adverse environmental conditions?
Presence of a peptidoglycan-rich cortex layer and a keratin-like spore coat
Which bacterial diseases are transmitted to humans by spores?
Anthrax, tetanus, botulism, gas gangrene
What temperature and pressure are recommended for proper sterilization to eradicate bacterial spores?
$121^{ ext{o}}$C, 15psi
In which environment do microbes grow in complex communities called biofilms?
All natural environments
What do biofilms offer to microbes?
Safety in numbers and increased resistance to adverse environmental conditions
Which type of infections involve biofilms according to the text?
$ ext{Pseudomonas aeruginosa}$ infections in cystic fibrosis patients
Why are biofilm infections difficult to treat?
Biofilm cells require higher antibiotic doses compared to planktonic cells
What substance do bacteria excrete to anchor themselves and form biofilms?
Slimy glue-like substances
What type of disease is woolsorters' disease?
Anthrax
Which bacteria form biofilms on implanted biomaterials and catheters according to the text?
Coagulase-negative staphylococci
What is the optimal pH range for most microorganisms to grow (neutrophiles)?
pH 6-8
What do halophiles thrive in?
High salt concentrations
What type of bacteria can form spores for protection from adverse conditions?
Some Gram-positive bacteria
How do psychrophiles differ from cold-active enzymes in terms of temperature tolerance?
Psychrophiles struggle to grow in environments with varying temperatures, while cold-active enzymes allow normal nutrient transport at low temperatures.
What is the primary factor influencing water availability and osmolarity for microbial growth?
$\text{Solute concentration}$
What is the role of water-miscible liquids like glycerol and DMSO in storing bacterial cultures at low temperatures?
They prevent microbial growth
What type of microbes increase internal solute concentration to obtain water and use compatible solutes?
Osmophiles
What do thermophiles thrive in?
High temperature environments
What happens when spores germinate in a wound site?
They cause infection
What is the most important environmental factor controlling microbial growth?
Temperature
What is the cardinal temperature that controls microbial growth?
Maximum
What happens to enzymes and proteins above the maximum temperature for microbial growth?
They are denatured
What may happen to the cell membrane below the minimum temperature for microbial growth?
It may no longer function
What type of temperature do organisms adapted for growth at cold temperatures prefer?
$10^\text{o}C - 20^\text{o}C$
What is altered depending on growth media with respect to cell membrane composition?
The cell membrane composition
What are ideal growth conditions for a microbe?
A temperature where all their enzymes are folded properly and working at the optimum rate
What do environmental conditions dictate with respect to microbial growth?
The distribution and habitats of microbes
What effect does too hot or too cold temperature have on microbial growth?
It can prevent growth
What is the primary focus of Koch's postulates?
Proving the association between a microorganism and a specific disease
Which factor can make the application of Koch's postulates challenging?
Difficulty in culturing some pathogens
What is a key differential in pathogens that helps them cause disease?
Presence of virulence factors
Which type of toxin targets cells lining the gut tract?
Enterotoxins
What do Clostridium botulinum and Clostridium tetanii secrete, leading to fatal paralysis?
Extremely potent neurotoxins
Which type of factor is directly involved in causing disease?
Virulence factor
Where are endotoxins primarily found?
In Gram-negative organisms
Which factor primarily blocks phagocytosis by forming a barrier?
Capsules
How do opportunistic pathogens take advantage of changes in environment?
They are already present and exploit environmental changes.
What serves as a barrier against infections by establishing colonies?
Mucous membranes
What triggers specific responses in acquired immunity?
Antigens recognized by antigenic determinants (epitopes)
What may provoke allergic reactions due to their properties?
'Antigens >5-100KDa'
What percentage of the final grade is allocated to practical assessments?
30%
When is the Practical Exam scheduled to be held?
Friday Nov 24th 2-3pm
What is the subject of Lecture 16?
Microbiology in the Food Industry - Fermentations
What is the primary focus of Industrial Microbiology?
Food and Beverage Industry
Which sector does Clinical Microbiology primarily impact?
Developing vaccines, antibiotics, new treatments
What is the percentage weightage for the end of term MCQ exam?
70%
How many practical reports are to be submitted online after the practicals?
Two reports
What is the role of bacteria in the biotech industry?
Producing antibiotics and probiotics
What does Lecture 12 focus on?
Pathogenic Bacteria
Which industry does Environmental Microbiology primarily impact?
Pollution and Bioremediation
What does Lecture 10 cover?
Microorganisms and Disease
What is the total weightage for practical assessments?
100%
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.
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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