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Questions and Answers
Clostridium species are classified as ______ anaerobes.
Clostridium species are classified as ______ anaerobes.
sporeforming
Streptococcus pyogenes is an ______ anaerobe.
Streptococcus pyogenes is an ______ anaerobe.
aerotolerant
Bacteroides species are classified as ______ bacilli.
Bacteroides species are classified as ______ bacilli.
gram-negative
C.botulinum is notorious for producing the ______ toxin.
C.botulinum is notorious for producing the ______ toxin.
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Staphylococcus aureus is known for causing skin infections and is often ______ resistant.
Staphylococcus aureus is known for causing skin infections and is often ______ resistant.
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O2 + e- → ______
O2 + e- → ______
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O2- + e- + 2H+ → ______
O2- + e- + 2H+ → ______
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H2O2 + e- + H+ → H2O + ______
H2O2 + e- + H+ → H2O + ______
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Superoxide dismutase (SOD) catalyzes the dismutation of the ______ radical.
Superoxide dismutase (SOD) catalyzes the dismutation of the ______ radical.
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Catalase catalyzes the decomposition of hydrogen peroxide to ______ and oxygen.
Catalase catalyzes the decomposition of hydrogen peroxide to ______ and oxygen.
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Anaerobic respiration with ethanol formation is also referred to as ______ fermentation.
Anaerobic respiration with ethanol formation is also referred to as ______ fermentation.
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C6H1206 + 6O2 → 6H2O + 6CO2 + ______ kJ signifies aerobic respiration.
C6H1206 + 6O2 → 6H2O + 6CO2 + ______ kJ signifies aerobic respiration.
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Fermentation by Clostridium results in ______ acid production.
Fermentation by Clostridium results in ______ acid production.
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Obligate anaerobes are harmed or killed by the presence of ______.
Obligate anaerobes are harmed or killed by the presence of ______.
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Micrococcus luteus is an example of an ______ that requires oxygen for aerobic respiration.
Micrococcus luteus is an example of an ______ that requires oxygen for aerobic respiration.
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Facultative anaerobes can grow either in the presence or absence of ______.
Facultative anaerobes can grow either in the presence or absence of ______.
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Streptococcus pyogenes is classified as an aerotolerant anaerobe, meaning that its growth is unaffected by ______.
Streptococcus pyogenes is classified as an aerotolerant anaerobe, meaning that its growth is unaffected by ______.
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Spirillum volutans is a ______ that requires oxygen at levels lower than atmospheric concentration.
Spirillum volutans is a ______ that requires oxygen at levels lower than atmospheric concentration.
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Methanobacterium formicicum employs ______ or anaerobic respiration to survive.
Methanobacterium formicicum employs ______ or anaerobic respiration to survive.
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In the reduction of O2 to H2O, several ______ forms of oxygen can be produced.
In the reduction of O2 to H2O, several ______ forms of oxygen can be produced.
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The upper respiratory tract is the habitat for ______ pyogenes, which is an aerotolerant anaerobe.
The upper respiratory tract is the habitat for ______ pyogenes, which is an aerotolerant anaerobe.
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Flashcards
Clostridium species
Clostridium species
Spore-forming anaerobes found in soil and intestines.
E.coli
E.coli
Facultative anaerobe, mostly harmless and beneficial in the intestines.
Streptococcus pyogenes
Streptococcus pyogenes
Aerotolerant anaerobe, infrequently pathogenic, can cause mild to severe infections.
Staphylococcus aureus
Staphylococcus aureus
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Obligate anaerobes
Obligate anaerobes
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Anaerobes
Anaerobes
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Facultative Anaerobes
Facultative Anaerobes
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Aerobes
Aerobes
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Microaerophilic
Microaerophilic
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Aerotolerant Anaerobes
Aerotolerant Anaerobes
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Oxygen as an Oxidant
Oxygen as an Oxidant
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Toxic Forms of Oxygen
Toxic Forms of Oxygen
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Superoxide
Superoxide
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Superoxide Dismutase (SOD)
Superoxide Dismutase (SOD)
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Hydrogen Peroxide
Hydrogen Peroxide
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Catalase
Catalase
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Peroxidase
Peroxidase
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Aerobic Respiration
Aerobic Respiration
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Alcohol Fermentation
Alcohol Fermentation
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Lactic Acid Fermentation
Lactic Acid Fermentation
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Study Notes
Course Information
- Course Title: Physiology and Screening of Industrial Microorganisms
- Course Code: SCCG 3673
- Academic Year: 2024/2025
- Level: 1
- Instructor: Dr. Praseetha Prabhakaran
- Email: [email protected]
- Location: T02, Level 4
Chapters
- Chapter 1: Introduction
- Chapter 2: Microbial Growth Requirement
- Chapter 3: Methods of Isolating Pure Cultures
- Chapter 4: Screening of Anaerobic Microorganisms
- Chapter 5: Screening of Thermophilic Microorganisms
- Chapter 6: Screening of Alkalophilic Microorganisms
- Chapter 7: Screening of Acidophilic Microorganisms
Microbial Growth Based on Oxygen Requirement
- Organism's oxygen requirement
- Test tubes labelled a to f illustrate growth location based on oxygen requirement in Fluid Thioglycolate Medium (FTM).
- Images display different growth patterns in the tubes showing how microbes respond to different oxygen conditions.
Anaerobes
- Obligate aerobes
- Require oxygen at atmospheric levels (21% O₂).
- Grow as a film (scum) or layer on the top of the liquid medium.
- Obligate anaerobes
- Killed by exposure to even small amounts of oxygen.
- Facultative anaerobes
- Grow in both aerobic and anaerobic conditions.
- Prefer aerobic conditions.
- Aerotolerant anaerobes
- Only grow in anaerobic conditions.
- Presence of oxygen has no effect on their growth.
- Microaerophiles
- Need a low level of oxygen (2-10% O₂).
- High oxygen concentrations are toxic.
Anaerobe Classification
- Group | Relationship to O₂ | Type of Metabolism | Example | Habitat
- --- | --- | --- | --- | ---
- Obligate | Required | Aerobic respiration | Micrococcus luteus | Skin, dust |
- Microaerophilic | Required but at levels lower than atmospheric | Aerobic respiration | Spirillum volutans | Water |
- Aerotolerant | Not required & presence of O₂ has no effect | Fermentation | Streptococcus pyogenes | Upper respiratory tract |
- Facultative | Not required, but growth is better with O₂ | Aerobic, anaerobic respiration, fermentation | Escherichia coli | Mammalian intestine |
- Obligate | Harmful or lethal | Fermentation or anaerobic respiration | Methanobacterium formicicum | Sewage sludge, digesters, anoxic lake sediments |
Why Oxygen is Lethal to Obligate Anaerobes
- Oxygen is a powerful oxidant and a good electron acceptor for respiration.
- Reduction of oxygen (O₂ to H₂O) in respiration produces harmful oxygen by-products.
Oxygen By-Products and Cellular Defense Mechanisms
- Superoxide dismutase (SOD)
- Enzyme catalyzing the dismutation of superoxide radicals into oxygen or hydrogen peroxide.
- Important antioxidant defense mechanism to protect cells from oxygen damage.
- Catalase
- Enzyme that decomposes hydrogen peroxide into water and oxygen.
- Protects cells from oxidative damage by Reactive Oxygen Species (ROS).
- Peroxidase
- Enzyme that converts hydrogen peroxide to water in the presence of hydrogen ions (NADH).
- Found in oxygen-tolerant anaerobic bacteria.
Types of Respiration
- Aerobic respiration
- Glucose + Oxygen → Water + Carbon Dioxide + Energy (2870 kJ)
- Anaerobic respiration (alcohol fermentation)
- Sugar → Ethanol + Carbon Dioxide + Energy (210 kJ)
- Anaerobic respiration (lactic acid fermentation)
- Sugar → Lactic Acid + Energy (150 kJ)
Other Fermentative Pathways
- Propionibacterium: propionic acid fermentation
- Clostridium: butyric acid fermentation
- Enterobacter: butanediol fermentation
Fermentation Products
- List of organisms and their fermentation products.
- Fermentation products include:
- Propionic acid
- Lactic acid
- Ethanol
- Acetic acid
- CO₂ (and more listed in table)
Classification of Important Anaerobes
- Gram-positive Cocci:
- Anaerobic Streptococcus
- Anaerobic Staphylococcus -Peptostreptococcus
- (species examples provided)*
- Gram-positive Bacilli:
-Sporeforming (species examples provided)
- Non-sporeforming (species examples provided)
- Gram-negative Cocci: -Veillonella
- (species examples provided)*
- Gram-negative Bacilli: -Bacteroides -Prevotella -Porphyromonas
- Fusobacterium
- (species examples provided)*
Examples of Important Anaerobes
- Escherichia coli:
- Facultative anaerobe
- Often harmless; some strains are harmful.
- Streptococcus pyogenes:
- Aerotolerant anaerobe.
- Associated with mild to life-threatening infections.
- Staphylococcus genus:
- Facultative anaerobe.
- Some strains cause infections; others are harmless.
- Clostridium genus:
- Obligate anaerobe.
- Spore-forming; some strains produce toxins causing serious diseases (e.g., botulism, tetanus).
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Description
This quiz focuses on the first chapter of the Physiology and Screening of Industrial Microorganisms course. It covers the introduction to microbial growth requirements and how different microbes adapt to varying oxygen environments. Test your understanding of key concepts and terminology in this foundational chapter.
