Question

What is quorum sensing with regard to biofilm formation?

Answer 1

Biofilm formation is a cooperative group behavior that involves bacterial populations living embedded in a self-produced extracellular matrix. QS is a cell-cell communication mechanism that synchronizes gene expression in response to population cell density.

Quorum sensing is the regulation of gene expression in response to fluctuations in cell-population density. Quorum sensing bacteria produce and release chemical signal molecules called autoinducers that increase in concentration as a function of cell density.

Bacterial quorum sensing systems enhance access to nutrients and more favorable environmental niches, and they enhance action against competing bacteria and environmental stresses.

The signal molecules, known as autoinducers, are secreted into the environment by bacteria and gradually increase in concentration as the bacteria population grows. For example, the bacterium Pseudomonas aeruginosa, which can cause pneumonia and blood infections, uses quorum sensing to regulate disease mechanisms.

Bacteria cells secrete molecules that can be detected by other bacteria. Quorum sensing allows bacteria to sense the concentration of these signaling molecules to monitor the local density of cells. Bacteria use quorum sensing to coordinate certain behaviors, such as biofilm production.

Quorum sensing is the regulation of gene expression in response to fluctuations in cell-population density. Quorum sensing bacteria produce and release chemical signal molecules called autoinducers that increase in concentration as a function of cell density. The detection of a minimal threshold stimulatory concentration of an autoinducer leads to an alteration in gene expression. Gram-positive and Gram-negative bacteria use quorum sensing communication circuits to regulate a diverse array of physiological activities. These processes include symbiosis, virulence, competence, conjugation, antibiotic production, motility, sporulation, and biofilm formation. In general, Gram-negative bacteria use acylated homoserine lactones as autoinducers, and Gram-positive bacteria use processed oligo-peptides to communicate. Recent advances in the field indicate that cell-cell communication via autoinducers occurs both within and between bacterial species.