Podcast
Questions and Answers
What role do autoinducers (AIs) play in microbial communities?
What role do autoinducers (AIs) play in microbial communities?
- Inhibiting the synthesis of extracellular enzymes.
- Preventing genetic material exchange between cells.
- Regulating cellular activity based on population density. (correct)
- Disrupting the formation of biofilms.
Which characteristic allows bacteria to respond to their surrounding environment?
Which characteristic allows bacteria to respond to their surrounding environment?
- The formation of endospores during times of stress.
- The ability to produce, accumulate, and sense autoinducers (AIs). (correct)
- The ability to rapidly replicate their DNA.
- The secretion of inhibitory substances that kill neighboring bacteria.
What is the significance of bacteria sensing AIs (autoinducers) reaching a critical limit?
What is the significance of bacteria sensing AIs (autoinducers) reaching a critical limit?
- Initiates the conjugation process for genetic exchange.
- Promotes the formation of flagella for enhanced motility.
- Leads to altered gene expression, either upregulating or downregulating specific genes. (correct)
- Triggers immediate cell death to prevent overpopulation.
Which of the following processes is NOT typically controlled by quorum sensing?
Which of the following processes is NOT typically controlled by quorum sensing?
What is the primary role of N-acyl-homoserine lactones (AHLs) in bacterial communication?
What is the primary role of N-acyl-homoserine lactones (AHLs) in bacterial communication?
How does the specificity of AHL signaling relate to the structure of the molecule?
How does the specificity of AHL signaling relate to the structure of the molecule?
What distinguishes Autoinducer-2 (AI-2) from other autoinducers in bacterial communication?
What distinguishes Autoinducer-2 (AI-2) from other autoinducers in bacterial communication?
What is a key characteristic of Autoinducer-3 (AI-3)?
What is a key characteristic of Autoinducer-3 (AI-3)?
How do bacteria utilize amino acids and small peptides in quorum sensing?
How do bacteria utilize amino acids and small peptides in quorum sensing?
Which transport mechanism is involved in exporting ribosomally synthesized peptides for quorum sensing?
Which transport mechanism is involved in exporting ribosomally synthesized peptides for quorum sensing?
A researcher is studying a new bacterial species that forms biofilms in food processing equipment. They suspect quorum sensing is involved. Which experiment would best support this hypothesis?
A researcher is studying a new bacterial species that forms biofilms in food processing equipment. They suspect quorum sensing is involved. Which experiment would best support this hypothesis?
A scientist discovers a new molecule that inhibits quorum sensing in a harmful bacterium. What potential application could this discovery have?
A scientist discovers a new molecule that inhibits quorum sensing in a harmful bacterium. What potential application could this discovery have?
You are studying a bacterium that produces a protease (an enzyme that breaks down proteins) only when it reaches high cell densities. What is the most likely mechanism regulating this protease production?
You are studying a bacterium that produces a protease (an enzyme that breaks down proteins) only when it reaches high cell densities. What is the most likely mechanism regulating this protease production?
Which of the following is a direct consequence of bacteria coordinating their behavior through quorum sensing?
Which of the following is a direct consequence of bacteria coordinating their behavior through quorum sensing?
A researcher is investigating a Gram-negative bacterium isolated from a spoiled food product. They find that it produces a signal molecule with a long acyl chain. What type of signal molecule is it most likely to be?
A researcher is investigating a Gram-negative bacterium isolated from a spoiled food product. They find that it produces a signal molecule with a long acyl chain. What type of signal molecule is it most likely to be?
How might disruption of AI-2 production specifically affect a mixed-species biofilm?
How might disruption of AI-2 production specifically affect a mixed-species biofilm?
A biofilm-forming bacterium has been genetically engineered to produce a modified AHL molecule that binds to, but does not activate, the native AHL receptor. What effect would this have on the bacterium's quorum sensing?
A biofilm-forming bacterium has been genetically engineered to produce a modified AHL molecule that binds to, but does not activate, the native AHL receptor. What effect would this have on the bacterium's quorum sensing?
If a bacterial species relies on a signal molecule that is ribosomally synthesized and transferred using ABC transporters, it's most likely:
If a bacterial species relies on a signal molecule that is ribosomally synthesized and transferred using ABC transporters, it's most likely:
In a scenario where researchers aim to reduce the pathogenicity of EHEC E. coli, which quorum sensing target would be most relevant?
In a scenario where researchers aim to reduce the pathogenicity of EHEC E. coli, which quorum sensing target would be most relevant?
How do bacteria benefit from their quorum sensing abilities?
How do bacteria benefit from their quorum sensing abilities?
Flashcards
Quorum sensing
Quorum sensing
Communication between microorganisms based on exchange of chemical molecules called Autoinducers (AIs).
Bacterial Response to AIs
Bacterial Response to AIs
The ability of bacteria to produce, accumulate and sense AIs, and therefore respond to their presence
AI Sensing Mechanism
AI Sensing Mechanism
Bacteria sense AIs at a critical limit, triggering gene expression changes (up or down regulation).
Quorum Sensing Effects
Quorum Sensing Effects
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N-acyl-homoserine lactones (AHLs)
N-acyl-homoserine lactones (AHLs)
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Furanosyl borate diester (AI-2)
Furanosyl borate diester (AI-2)
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Autoinducer 3 (AI-3)
Autoinducer 3 (AI-3)
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Amino acids and small peptides
Amino acids and small peptides
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Study Notes
- FSN2010 is advanced food microbiology.
- Topic: Quorum sensing phenomena in microorganisms
Communication of Microorganisms
- Communication occurs through the exchange of chemical molecules/signals with a small molecular weight known as autoinducers (AIs).
- This phenomenon allows microorganisms to control or sense their surroundings/environment based on the presence of other microorganisms and to respond to changes through certain mechanisms.
- Bacteria can produce, accumulate, and sense Als, which allows them to respond to their presence.
- Bacteria can sense AIs when their concentration reaches a critical limit, triggering the expression of certain genes (downregulation or upregulation) as a response.
Processes Controlled via Quorum Sensing
- Bioluminescence
- Biofilm formation (e.g., Pseudomonas aeruginosa, Hydromonas hydrophila)
- Spore formation
- Production of antibiotics and bacteriocins (e.g., Streptomyces, Serratia, Erwinia)
- Pathogenicity of certain species (EPEC, EHEC)
- Plasmid transfer
Main Groups of Bacterial Signal Molecules
N-acyl-homoserine lactones (AHLs)
- By-products of fatty acids, used mostly by Gram-negative bacteria to communicate within the same species.
- They are known as Autoinducers 1 (AI-1).
- Approximately 7% of bacteria can produce these compounds.
- Acyl-chain structures contain 4 to 18 C-atoms, with a H-, OH-, or no substitute in the C3 atom.
- Specificity depends on the differences within the acyl-chain and the presence or absence of substitutes.
- Limited chemical variability.
- Transferred through diffusion mechanisms from cell membranes, with larger molecules using active transfer mechanisms.
Furanosyl borate diester or AI-2
- Also called Autoinducer 2 (AI-2).
- Produced by both Gram-positive and Gram-negative bacteria.
- Used for communication among the same and different species.
- Universal quorum sensing molecule.
Autoinducer -3
- Autoinducer 3 (AI-3) has an unknown structure.
- Used for communication between kingdoms.
- Contributes to the pathogenicity of EHEC E. coli.
Amino acids and small peptides
- Produced and utilized by Gram-positive bacteria.
- Ribosomically synthesized, processed, and exit the cell via a process binding ATP, through a protein-transfer ABC
- Known for small size, being very stable, great variety, and high specificity.
- Linear examples include Streptococcus pneumonia and Lactobacillus plantarum.
- Cyclical molecules include Staphylococcus aureus and Enterococcus faecalis.
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