During biofilm formation, increased quorum sensing enables bacteria to _____________

Question

BlackTom AI · Accepted Answer

Quorum sensing coordinates gene expression across a bacterial population using secreted signaling molecules (autoinducers), and when these signals reach a threshold concentration they trigger collective behaviors such as biofilm matrix production.

1. Relevant knowledge points and concepts
- Quorum sensing (QS): cell–cell communication using autoinducers; response depends on population density. 
- Biofilm formation stages: initial attachment, microcolony formation, synthesis of extracellular polymeric substances (EPS), maturation, and dispersal. 
- EPS composition and role: polysaccharides, proteins, extracellular DNA that form the matrix providing structural integrity, adhesion, nutrient retention, and protection.

2. Step-by-step reasoning
- Early attachment is often mediated by flagella, pili and adhesins when cells contact a surface.
- As cells multiply and local autoinducer concentration rises, QS systems activate transcriptional programs.
- Among those QS-regulated programs are genes encoding EPS biosynthesis enzymes and secretion systems.
- Increased EPS production transforms loosely attached cells into a cohesive biofilm community and enables maturation.

3. (No numerical calculations are required for this conceptual question.)

4. Why the correct answer is correct
- “Regulate EPS production” matches the known role of QS: at high cell density QS upregulates genes for polysaccharide and matrix component production (examples: alginate, Psl, Pel in Pseudomonas aeruginosa). This regulation is essential for forming the protective biofilm matrix and for biofilm architecture and function.

5. Why the other options are incorrect
- “Secrete endospores”: endospore formation is a sporulation process in some Gram-positive bacteria (e.g., Bacillus) and is not driven by QS to produce spores; it’s a survival differentiation, not a general QS-driven biofilm feature. 
- “Form planktonic cells”: planktonic refers to free-floating cells; QS in biofilm context promotes sessile, collective behaviors (matrix formation) rather than producing planktonic cells. 
- “Attach to a surface”: initial attachment is typically QS-independent and relies on adhesins and motility structures; QS primarily regulates later steps such as EPS production and maturation.

6. Conclusion
Therefore, increased quorum sensing during biofilm formation enables bacteria to regulate EPS production — confirming the provided answer: regulate EPS production.

During biofilm formation, increased quorum sensing enables bacteria to _____________单项选择题

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