Bacterial Response to Oxygen

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Questions and Answers

Bacteria may be divided into three groups according to their response to free molecular ______.

oxygen

Strict aerobes die in an ______ digester where free molecular oxygen is absent.

anaerobic

Facultative anaerobes are active in the presence or absence of free molecular ______.

oxygen

When nitrate ions are used by facultative anaerobes for degradation, ______ occurs, producing dinitrogen gas.

denitrification Signup and view all the answers

Approximately ______% of the bacteria within aerobic processes are facultative anaerobes.

80 Signup and view all the answers

Anaerobes are inactive in the presence of free molecular ______.

oxygen Signup and view all the answers

Strong acid producers among anaerobes include organisms like ______ spp.

streptococcus Signup and view all the answers

Oxygen-tolerant anaerobes cannot perform normal cellular activities, including the degradation of ______, in the presence of molecular oxygen.

substrate Signup and view all the answers

Match each group of bacteria with their characteristics:

Strict Aerobes = Degrade substrates only in the presence of free molecular oxygen Facultative Anaerobes = Active in both the presence and absence of free molecular oxygen Oxygen-Tolerant Anaerobes = Survive in the presence of free molecular oxygen but cannot degrade substrates Strict Anaerobes = Inactive in the presence of free molecular oxygen Signup and view all the answers

Match the following bacteria with their specific roles:

Nitrobacteria spp = Produce a variety of acids and alcohols, CO2, and hydrogen Escherichia coli = Produce malodorous compounds such as indole and skatole Streptococcus spp = Strong acid producers among anaerobes Desulfomarculum spp = Reduce sulfate (SO42-) to hydrogen sulfide (H2S) Signup and view all the answers

Match the following processes with the type of bacteria responsible:

Activated Sludge = Composed mainly of facultative anaerobes Trickling Filters = Utilize large numbers of strict aerobes Anaerobic Digesters = Inhabit oxygen-intolerant species Denitrification = Involves the use of nitrate ions by facultative anaerobes Signup and view all the answers

Match the following features with the correct type of bacteria:

Strict Aerobes = Present in aerobic fixed-film processes Facultative Anaerobes = Utilize nitrate for waste degradation when oxygen is absent Oxygen-Tolerant Anaerobes = Cannot perform normal cellular activities in the presence of oxygen Strict Anaerobes = Cannot survive in the presence of free oxygen Signup and view all the answers

Match each type of anaerobic bacteria with their oxygen tolerance type:

Oxygen-Tolerant Anaerobes = Survive but do not thrive in the presence of oxygen Oxygen-Intolerant Anaerobes = Active only in anaerobic conditions Facultative Anaerobes = Adapts to both aerobic and anaerobic conditions Strict Anaerobes = Die in the presence of free molecular oxygen Signup and view all the answers

Match the following substances with the processes they participate in:

Methanol (CH3OH) = Degraded by facultative anaerobes when oxygen is absent Nitrate ion (NO3) = Used in denitrification by facultative anaerobes Carbohydrates = Degraded by facultative anaerobic bacteria in anaerobic digesters Hydrogen Sulfide (H2S) = Produced by the reduction of sulfate by anaerobic bacteria Signup and view all the answers

Match the following statements with their correct bacteria group:

Strict Aerobes = Die quickly without oxygen Facultative Anaerobes = Can switch between aerobic and anaerobic metabolism Oxygen-Tolerant Anaerobes = Survive in aerobic environments but are inactive Strict Anaerobes = Thrive only in anaerobic conditions Signup and view all the answers

Match each characteristic with the correct type of metabolic activity:

Degradation in the presence of oxygen = Characteristic of Strict Aerobes Denitrification resulting in N2 production = A role of Facultative Anaerobes Activity leads to strong acid production = A characteristic of certain Anaerobes Inhabit aerobic processes but are inactive with oxygen = Describes Oxygen-Tolerant Anaerobes Signup and view all the answers

Study Notes

Bacterial Response to Oxygen

Strict aerobes:
- Require free molecular oxygen for survival and activity.
- Found in large numbers in aerobic processes like trickling filters and activated sludge.
- Play a significant role in waste degradation.
- Cannot survive in anaerobic environments (where free molecular oxygen is absent).
Facultative anaerobes:
- Thrive with or without free molecular oxygen.
- Utilize free molecular oxygen for enzymatic activity and waste degradation when available.
- Can use alternative molecules like nitrate ions (NO3-) for degradation when oxygen is absent, leading to denitrification and production of dinitrogen gas (N2).
- Make up approximately 80% of bacteria in aerobic processes like fixed-film and suspended growth systems.
- Found in both aerobic and anaerobic processes.
- In anaerobic digesters, they produce acids, alcohols, carbon dioxide, and hydrogen from various waste components.
- Some species, like Escherichia coli, produce malodorous compounds like indole and skatole.
Anaerobes:
- Inactive in the presence of free molecular oxygen.
- Divided into two subgroups: oxygen-tolerant and oxygen-intolerant (strict anaerobes).
- Oxygen-tolerant anaerobes can survive in the presence of oxygen but cannot perform normal cellular activities.
- Strict anaerobes, including methane-forming bacteria, die in the presence of oxygen.
- Some examples include:
  - Streptococcus spp: strong acid producers.
  - Desulfomarculum spp: reduce sulfate (SO42-) to hydrogen sulfide (H2S).

Bacteria and Oxygen

Bacteria are divided into three groups based on their oxygen requirements: strict aerobes, facultative anaerobes, and anaerobes.
Strict aerobes require oxygen for growth and survival. They are prevalent in aerobic wastewater treatment processes like trickling filters and activated sludge.
Facultative anaerobes can thrive with or without oxygen. They utilize oxygen when available but can switch to alternative electron acceptors like nitrates (NO3-) when oxygen is scarce. This process is called denitrification and results in the production of nitrogen gas (N2).
Anaerobes cannot tolerate oxygen and are divided into two subgroups: oxygen-tolerant and oxygen-intolerant (strict anaerobes).
- Oxygen-tolerant anaerobes can survive in the presence of oxygen but cannot perform cellular activities like substrate degradation.
- Oxygen-intolerant anaerobes die in the presence of oxygen. They include methane-forming bacteria crucial for anaerobic digestion.

Anaerobic Digestion

Facultative anaerobes play a significant role in anaerobic digestion. They produce acids, alcohols, carbon dioxide, and hydrogen from carbohydrates, lipids, and proteins.
Some facultative anaerobes, like Escherichia coli, produce malodorous compounds such as indole and skatole.
Anaerobes, like Streptococcus spp, are strong acid producers in anaerobic environments.
Others, such as Desulfomarculum spp, reduce sulfate (SO42-) to hydrogen sulfide (H2S).

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Description

This quiz explores the different types of bacteria based on their oxygen requirements, including strict aerobes and facultative anaerobes. It details their survival mechanisms, roles in waste degradation, and their presence in various environmental processes. Understand the crucial functions these bacteria perform in both aerobic and anaerobic environments.