Week 14 / Microbiology 4

Question 1

Flashcard Question:
What are the classifications of organisms based on their sources of carbon, energy, and electrons?

What can all of these classifications combined be called?

Answer 1

1. Carbon Sources:
   
   • Autotrophs: Use CO₂ as their sole or primary carbon source.
   • Heterotrophs: Obtain carbon from other organisms.
2. Energy Sources:
   
   • Phototrophs: Harness energy from light.
   • Chemotrophs: Obtain energy from the oxidation of compounds.
3. Electron Sources:
   
   • Lithotrophs: Utilize reduced inorganic compounds as electron sources.
   • Organotrophs: Use organic molecules as electron source

These terms may be joined together e.g. “chemoorganoautotroph”

Question 2

Flashcard Question:
What are the two primary methods for culturing microorganisms, and how do they differ?

Answer 2

1. Liquid Media (Broth):
   
   • Originally developed by Koch in the late 19th century using potato slices and gelatin.
   • Bacteria grow as individual cells until nutrients are exhausted, resulting in a suspension of cells.
   • Unable to distinguish between multiple cell types without further testing.
2. Solid Media (Agar Plates):
   
   • Bacteria and fungi form distinct colonies on solid media.
   • Each colony theoretically originates from a single cell, facilitating culture purification.
   • Colony appearance can be influenced by the media formula, leading to selective and differential media.
   • Formulas for solid media are generally similar to liquid media, with the addition of a gelling agent (agar).

This flashcard format presents the information clearly, making it easy to study and review the key points regarding microorganism culture methods.

Question 3

What are the different atmospheric requirements for microorganisms, and can you provide examples?

Answer 3

Flashcard Answer:

1. Obligate Aerobe:
   
   • Example: Mycobacterium tuberculosis
   • Description: Cannot survive without oxygen.
2. Obligate Anaerobe:
   
   • Example: Clostridium difficile
   • Description: Cannot survive (killed) in the presence of oxygen.
3. Facultative Aerobe:
   
   • Examples: Staphylococcus aureus and E. coli
   • Description: Can grow in the presence of oxygen or produce energy by fermentation.
4. Microaerophile:
   
   • Example: Campylobacter jejuni
   • Description: Requires reduced oxygen content (increased CO₂ content) to survive.
5. Aerotolerant Anaerobe:
   
   • Example: Streptococcus mutans
   • Description: Can tolerate oxygen in the air but produces energy by fermentation.

Question 4

Here’s the information in flashcard format:

Flashcard Question:
What are the methods available for culturing anaerobic (or aerotolerant) microorganisms?

Answer 4

Flashcard Answer:

1. Anaerobic Cabinet:
   
   • Description: Large isolator cabinets that maintain anaerobic conditions.
   • Atmosphere: Typically composed of 95% nitrogen (N₂) and 5% hydrogen (H₂) with a palladium catalyst.
   • Pressure: Can be maintained under positive pressure.
2. GasPak Sachets:
   
   • Description: Sachets that produce CO₂ and H₂ from the breakdown of citric acid, cobalt chloride, and sodium borohydride.
   • Function: Help create an anaerobic environment in sealed containers.
3. Candle Extinction Method:
   
   • Description: Uses a candle to burn oxygen in a jar.
   • Function: Consumes oxygen, but may not achieve a true anaerobic environment.
4. Limitations:
   
   • Both GasPak and candle methods rarely produce a completely true anaerobic environment.

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Question 5

Here’s the information in flashcard format:

Flashcard Question:
What are the key points regarding bacterial reproduction and growth phases?

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Answer 5

Flashcard Answer:

1. Independent Survival:
   
   • Each bacterial cell can survive and reproduce independently.
2. Reproduction Methods:
   
   • Binary Fission: Most bacteria reproduce by this method.
   • Budding: Some bacteria reproduce by budding.
3. Generation Time:
   
   • Definition: The time taken for a bacterium to reproduce.
   • Variation: Varies widely between species.
   • Examples:
     
     • Escherichia coli: ~30 minutes.
     • Mycobacterium leprae: ~14 days.
4. Phases of Bacterial Growth:
   
   • Bacterial growth occurs in 4 distinct phases.

Question 6

Flashcard Question:
What are the phases of bacterial growth and their characteristics?

Answer 6

Flashcard Answer:

1. Lag Phase:
   
   • Description: No immediate increase in cell number.
   • Reason: Old cells are depleted and need time for the synthesis of new cell components and metabolites.
2. Exponential (Log) Phase:
   
   • Description: Growth and division occur at the maximum possible rate given the organism’s genetic potential and environmental conditions.
   • Characteristic: Regular doubling time.
3. Stationary Phase:
   
   • Description: In a closed system, nutrients become depleted and waste products build up.
   • Outcome: Growth ceases or is balanced by cell death.
   • Changes: Morphological and metabolic changes occur, such as secondary metabolism.
4. Death Phase (Senescence):
   
   • Description: Characterized by severe nutrient deprivation.
   • Consequence: Build-up of toxic waste products.
   • Outcome: Viable cell numbers decline at an exponential rate.

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Question 7

Here’s the information on microbial metabolism in flashcard format:

Flashcard Question:
What are the differences between primary metabolism and secondary metabolism in microorganisms?

Answer 7

Flashcard Answer:

1. Primary Metabolism:
   
   • Description: Includes major metabolic pathways essential for life.
   • Functions:
     
     • Energy production and release.
     • Synthesis of cell components.
     • Production of enzymes.
2. Secondary Metabolism:
   
   • Description: Involves non-essential metabolic pathways.
   • Functions:
     
     • Production of natural products, such as antibiotics.
     • Production of secondary metabolites that can increase pathogenicity in disease states (e.g., pyocyanin).

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Question 8

Here’s the information about laboratory scale culture in batch culture format:

Flashcard Question:
What are the characteristics and limitations of laboratory scale batch cultures?

!

Answer 8

Flashcard Answer:

1. Flask Cultures:
   
   • Type: Closed systems used for batch culture.
   • Purpose: Primarily used for optimization of steps in microbial growth and production.
2. Characteristics:
   
   • Nutrient availability is limited, affecting growth.
   • Atmospheric conditions are restricted due to diffusion at the liquid surface.
   • Limited product production capabilities.
3. Limitations:
   
   • Not suitable for industrial applications.
   • Primarily intended for laboratory-scale studies only.

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Question 9

Here’s the information about laboratory scale continuous culture in flashcard format:

Flashcard Question:
What are the characteristics and advantages of laboratory scale continuous cultures using chemostats?

Answer 9

Flashcard Answer:

1. Chemostats:
   
   • Type: Open systems used for continuous culture.
2. Characteristics:
   
   • Allows for highly controlled growth conditions.
   • Nutrients are supplied at a constant rate, ensuring consistent availability.
3. Advantages:
   
   • Maintains cells in the exponential growth phase for extended periods.
   • Facilitates the study of microbial physiology and metabolism under steady-state conditions.

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Question 10

Here’s the information about bulk culturing in flashcard format:

Flashcard Question:
What are the three growth modes in bulk culturing, and what are the important criteria to maintain?

Answer 10

Flashcard Answer:

1. Growth Modes:
   
   • Batch: All components are added at the start of the process.
   • Fed Batch: Fill the vessel until full, with nutrients added during the process.
   • Continuous: Fill the vessel and allow overflow to maintain volume.
2. Important Criteria:
   
   • Mixing: Maintain adequate mixing to ensure homogeneity.
   • Oxygen Levels: Maintain high oxygen levels if the culture is aerobic.
   • pH Control: Control the pH to optimize growth conditions.
   • Temperature Control: Ensure that the temperature is kept within the desired range.
   • Foam Control: Manage foam production to prevent overflow and loss of culture.
   • Initial Starting Concentration: Set the appropriate initial concentration of microorganisms for optimal growth.

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Question 11

Flashcard Question:
How do viruses replicate in eukaryotes compared to prokaryotes, and what are the key characteristics of their replication?

Answer 11

Flashcard Answer:

1. Eukaryotic Viruses:
   
   • Budding: Viruses often bud from the host cell rather than destroying it.
   • Examples:
     
     • Influenza
     • HIV
   • Replication: Relies on subversion of the host’s replication machinery.
2. Prokaryotic Viruses (Bacteriophages):
   
   • Subversion: Also subvert the host replication machinery.
   • Outcome: This often leads to cell destruction through a process called lytic replication.
3. Key Characteristics:
   
   • Both eukaryotic and prokaryotic viruses utilize the host’s cellular mechanisms for replication, but the outcomes differ—budding in eukaryotes and cell destruction in prokaryotes.

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Question 12

Here’s the information about bacterial evolution in flashcard format:

Flashcard Question:
What are the key concepts and consequences of bacterial evolution?

Answer 12

Flashcard Answer:

1. Definition of Evolution:
   
   • Changes in population over time due to various causes.
2. Causes of Evolution:
   
   • Acquisition of New Genes: Bacteria can gain new genetic material through processes like horizontal gene transfer.
   • Mutation of Existing Genes: Changes in existing genes can also drive evolution.
3. Consequences of Bacterial Evolution:
   
   • Positive Outcomes:
     
     • Increased product yield (beneficial for industrial applications).
   • Negative Outcomes:
     
     • Development of pathogenic strains.
     • Increased resistance to treatment (e.g., antibiotics).
4. Rate of Evolution:
   
   • Varies by organism; generally, more complex organisms evolve at a slower rate.

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Question 13

Here’s the information about bacterial evolution and mutation in flashcard format:

Flashcard Question:
What are the characteristics and types of mutations in bacterial evolution?

Answer 13

Flashcard Answer:

1. Definition of Mutation:
   
   • A permanent change in a single cell that does not necessarily cause any noticeable change or get passed on.
2. Causes of Mutations:
   
   • UV Irradiation: Exposure to ultraviolet light can induce mutations.
   • Chemical Exposure: Certain chemicals can cause changes in the DNA.
   • Poor Genome Copy: Errors during DNA replication can lead to mutations.
3. Types of Mutations:
   
   • Harmful (Deleterious) Mutations: Decrease the organism’s fitness.
   • Beneficial (Advantageous) Mutations: Increase the organism’s fitness, promoting desirable traits (e.g., increased product yield).
   • Neutral Mutations: Have no harmful or beneficial effect and occur at a steady rate.
4. Impact of Mutations:
   
   • Some mutations may promote traits that are harmful to other organisms, contributing to ecological dynamics.

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Question 14

Here’s the information about dorm

Flashcard Question:
What are the characteristics of viruses that can lie dormant, and how do they replicate?

Answer 14

Flashcard Answer:

1. Dormant Viruses:
   
   • Some viruses can remain dormant and still cause human diseases.
   • Examples:
     
     • Herpes simplex virus
     • Human papillomavirus
2. Bacteriophages:
   
   • Some bacteriophages can integrate their genome into the host’s genome.
3. Lysogenic Replication:
   
   • Description: Viruses replicate alongside the host without immediately destroying it.
   • Potential Transition: They can enter lytic replication under favorable conditions, leading to cell destruction.
4. Significance:
   
   • Lysogenic replication is important for the spread of bacterial genes through horizontal gene transfer.

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Question 15

Flashcard Question:
What are the characteristics and types of mutations in bacterial evolution

Answer 15

Flashcard Answer:

1. Definition of Mutation:
   
   • A permanent change in a single cell that does not necessarily cause any noticeable change or get passed on.
2. Causes of Mutations:
   
   • UV Irradiation: Exposure to ultraviolet light can induce mutations.
   • Chemical Exposure: Certain chemicals can cause changes in the DNA.
   • Poor Genome Copy: Errors during DNA replication can lead to mutations.
3. Types of Mutations:
   
   • Harmful (Deleterious) Mutations: Decrease the organism’s fitness.
   • Beneficial (Advantageous) Mutations: Increase the organism’s fitness, promoting desirable traits (e.g., increased product yield).
   • Neutral Mutations: Have no harmful or beneficial effect and occur at a steady rate.
4. Impact of Mutations:
   
   • Some mutations may promote traits that are harmful to other organisms, contributing to ecological dynamics.

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Question 16

Here’s the information about bacterial evolution and DNA acquisition in flashcard format:

Flashcard Question:
What are the three main mechanisms by which bacteria can acquire DNA and evolve?

Answer 16

Flashcard Answer:

1. Transformation:
   
   • Description: Direct uptake of DNA through the cell membrane from the environment.
   • Mechanism: Bacteria can absorb free-floating DNA from lysed cells.
2. Transduction:
   
   • Description: Introduction of genetic material via a viral vector (bacteriophage).
   • Mechanism: A bacteriophage infects a bacterium, incorporates some of its DNA, and transfers it to another bacterium.
3. Conjugation:
   
   • Description: Transfer of genetic material between two directly connected bacteria.
   • Mechanism: Often involves a pilus (a hair-like structure) that forms between the two bacteria to facilitate DNA transfer.

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Question 17

Flashcard Question:
How does antibiotic usage contribute to bacterial antimicrobial resistance?

Answer 17

Flashcard Answer:

1. Selective Pressure:
   
   • Antibiotic usage acts as a selective pressure on bacterial populations.
2. Impact on Competition:
   
   • By killing susceptible cells, antibiotics remove competition for resistant cells, allowing resistant bacteria to thrive and multiply.
3. Resistance Development:
   
   • Antimicrobial resistance is unlikely to result from a single mutation; it often involves multiple genetic changes and mechanisms that enhance survival in the presence of antibiotics.

Question 18

Here’s the information about strain improvement in flashcard format:

Flashcard Question:
What are the methods and considerations for bacterial strain improvement in production?

Answer 18

Flashcard Answer:

1. Need for Strain Improvement:
   
   • Initial strains may produce products at low concentrations, so there’s a need to boost production efficiency.
2. Natural Improvement:
   
   • Bacterial strains can improve naturally through spontaneous mutation, which is usually random and infrequent.
3. Risks of Mutation:
   
   • While mutations can enhance production, they can also make things worse.
4. Inducing Mutations:
   
   • Exposure to Mutagens: Increases the frequency of mutations (e.g., UV light or chemical exposure).
   • Random Mutagenesis: Randomly induces mutations to create variants.
5. Selection of Mutants:
   
   • Mutants can be picked and assessed for increased production.
6. Genetic Modification:
   
   • Targeted Mutagenesis: Involves adding, removing, or altering genes to improve overall yield.

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Question 19

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Answer 19

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