Quorum sensing (introduced in Ch. 11, Section 11.4) allows bacteria to detect the number of neighboring cells and to trigger a response only when this number reaches a critical level. Quorum sensing is used by V. fischeri in light production and by many pathogenic bacteria, including Vibrio cholerae, to turn on genes for toxin production only when a critical cell density is reached. Why might quorum sensing be beneficial to pathogenic bacteria?

Verified step by step guidance

1. Understand the concept of quorum sensing: Quorum sensing is a communication mechanism used by bacteria to coordinate certain behaviors based on the density of their population. Bacteria release signaling molecules called autoinducers, which increase in concentration as a function of cell density.
2. Recognize the role of quorum sensing in regulating gene expression: When the concentration of autoinducers reaches a threshold level, it triggers a signal transduction pathway that leads to changes in the expression of specific genes.
3. Consider the benefits of density-dependent behavior: For pathogenic bacteria, coordinating behavior based on cell density can be advantageous. It allows them to remain undetected at low densities when they are more vulnerable to the host's immune system.
4. Analyze the strategic activation of virulence factors: By using quorum sensing to regulate the production of toxins and other virulence factors, pathogenic bacteria can maximize their impact by waiting until they have amassed enough cells to overcome host defenses effectively.
5. Evaluate the ecological implications: Quorum sensing enables pathogenic bacteria to optimize resource use and energy expenditure, enhancing their survival and competitiveness in the host environment.