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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.
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Approximately ______% of the bacteria within aerobic processes are facultative anaerobes.
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Anaerobes are inactive in the presence of free molecular ______.
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Strong acid producers among anaerobes include organisms like ______ spp.
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Oxygen-tolerant anaerobes cannot perform normal cellular activities, including the degradation of ______, in the presence of molecular oxygen.
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Match each group of bacteria with their characteristics:
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Match the following bacteria with their specific roles:
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Match the following processes with the type of bacteria responsible:
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Match the following features with the correct type of bacteria:
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Match each type of anaerobic bacteria with their oxygen tolerance type:
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Match the following substances with the processes they participate in:
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Match the following statements with their correct bacteria group:
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Match each characteristic with the correct type of metabolic activity:
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Study Notes
Bacterial Response to Oxygen
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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).
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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.
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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).
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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.