Why in News?
- Alternative to Antibiotics: Leading molecular biologist Bonnie Bassler highlighted how targeting QS—rather than killing bacteria directly—could revolutionise the treatment of deadly infections like cholera without triggering antibiotic resistance.
Key Information & Mechanisms
- The Process: Bacteria continuously produce and release small signaling molecules called autoinducers. As the population grows, the concentration of these molecules increases until it reaches a "critical threshold" or quorum.
- Group Actions: Once the threshold is met, the entire bacterial colony simultaneously activates specific genes to perform tasks that would be impossible for a single cell, such as:
- Bioluminescence: Glowing in unison (first discovered in Vibrio fischeri).
- Virulence: Launching coordinated attacks on a host.
- Biofilm Formation: Creating a protective slime layer that makes them up to 1,500 times more resistant to antibiotics.
- Chemical Languages: Different types of bacteria use different "languages":
- Gram-Negative: Primarily use AHLs (Acyl-homoserine lactones).
- Gram-Positive: Primarily use AIPs (Autoinducing peptides).
- Universal: The molecule AI-2 acts as a "universal language" for inter-species communication between different types of bacteria.
- Quorum Quenching (QQ): This is the process of disrupting these signals. By using enzymes (like lactonases) or synthetic molecules to "jam" the signal, scientists can disarm pathogens without killing them, which prevents the bacteria from evolving resistance.
- Beyond Bacteria: QS-like logic has been observed in viruses (bacteriophages deciding whether to kill or hide in a host), social insects (ants and bees choosing nest sites), and even in human immune cells.
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